CN102102559A - Compression releasing engine braking method and device - Google Patents

Abstract

The invention discloses a compression releasing engine braking method and device. A primary piston hole and a secondary piston hole connected with a hydraulic passage are formed in a valve bridge, and a primary piston and a secondary piston in the piston holes are driven by using a braking lug boss of a cam to open an exhaust valve for braking. During braking, the retraction position of the primary piston is kept by using the equal altitude section of the braking cam at the maximum braking lift, the hydraulic passage between the primary piston hole and the secondary piston hole is closed, and the braking load on the secondary piston is transferred to a braking bracket positioned on the valve bridge and is not returned to the primary piston. The primary piston is further driven by using an integrated exhaust lug boss on the cam, the primary piston drives the valve bridge to move and is separated from the braking bracket, and an oil discharge passage in the valve bridge is opened to discharge oil, so that the secondary piston returns to the retraction position, and the braking exhaust door is moved to a closed position. A compression releasing braking mechanism is integrated with a traditional air valve driving chain, and the braking bracket bears the braking load and the weight braking valve lift, so the braking load is reduced and the braking power is increased.

Description

A compression release type engine braking method and device

Technical field:

The invention relates to the mechanical field, in particular to the valve driving field of a vehicle engine, in particular to a compression release type engine braking method and device.

Background technique:

Engine braking can be classified into compression release type braking and vent type braking. The engine's compression-release brake opens the exhaust valve at the end of the engine piston's compression stroke and closes the exhaust valve at the beginning of the expansion stroke (generally before the exhaust valve normally opens). A precedent for a compression release brake was disclosed in US Patent No. 3,220,392 in 1965 by Cummins. The brake system transmits the mechanical input through the hydraulic circuit to the exhaust valve to open. The hydraulic circuit typically includes a main piston that reciprocates within a main piston bore from a mechanical input to the engine, such as movement of an engine injection cam or movement of an adjacent exhaust cam. The movement of the main piston is transmitted to the auxiliary piston on the hydraulic circuit through the hydraulic fluid, causing it to reciprocate in the hole of the auxiliary piston. The auxiliary piston directly or indirectly acts on the exhaust valve to generate valve movement for engine braking operation.

The bleed-type braking of the engine is that in addition to the normal opening of the exhaust valve, it also keeps a small amount of constant opening in part of the cycle (partial cycle bleed brake), or in the cycle of the non-exhaust stroke (intake stroke, compression Stroke, and expansion stroke) keep a small amount of constant opening (full cycle bleed brake). The main difference between part-cycle bleed braking and full-cycle bleed braking is that the former does not open the exhaust valve for most of the intake stroke. The present inventors provide a related description and examples of a run-flat engine braking system and method in US Patent No. 6,594,996.

There are two main differences between engine compression-release braking and vent braking. The first major difference is the opening phase (braking time) of the brake exhaust valve. The brake exhaust valve of the full-cycle bleed brake is always open, so the opening time is not involved. The opening time of the brake exhaust valve of the partial cycle bleed type braking is in the late period of the engine's intake stroke; while the opening time of the brake exhaust valve of the compression release type braking is in the late period of the engine's compression stroke, compared with Part-cycle bleed brakes open the brake exhaust valve much later and therefore with a much greater load. The second main difference is that the opening height of the brake exhaust valve (brake valve lift) is different. The brake valve lift of the brake exhaust valve of the deflated brake is roughly 0.5-1.0mm (generally less than 1.0mm), while the brake valve lift of the brake exhaust valve of the compression release brake is roughly 2.0-3.5 mm (the brake valve lift of the hydraulic brake is generally greater than 2.0mm). The above differences lead to differences in design requirements and braking performance. The braking power of the compression release type is greater than that of the vent type brake, but the brake opening load of the vent type brake is much smaller than that of the compression release type brake. Bleed-type brakes must be used in conjunction with exhaust brakes (such as exhaust butterfly valves), while compression-release brakes can be used alone (no exhaust brake is required).

A precedent for an engine full-cycle blow-down braking system was disclosed in US Patent No. 3,525,317 in 1970 by Muir. This braking system divides engine braking into three gears. First gear is braking due to frictional losses from the engine and various moving parts of the vehicle. The second gear is a full-cycle bleed brake produced by keeping the exhaust valve of the engine continuously open for a small amount. The third gear is to increase the exhaust butterfly valve on the basis of the full-cycle bleed brake of the second gear to produce combined braking.

In 1992, Kubis of MAN disclosed an engine part-period exhaust brake system in U.S. Patent No. 5,086,738. When the engine is braking, the exhaust valve opens a small amount at the end of the engine intake stroke, then keeps a small amount of constant opening during the entire compression stroke, and finally closes at the beginning of the engine's expansion stroke.

As mentioned earlier, the engine vent brake is not effective alone, and the braking power is much lower than that of the compression release brake. Therefore, engine exhaust brakes are used in conjunction with engine exhaust brakes (such as exhaust butterfly valves) to form combined braking. Using exhaust butterfly valves or other exhaust flow restriction devices to increase exhaust back pressure may cause the exhaust valve to bounce or float (float valve). The engine industry generally does not approve of the float valve, because the opening and closing of the exhaust valve is not driven by the cam during the float valve, and the seating speed of the valve cannot be controlled. Too much valve seating speed may damage the engine. However, PacBrake of Canada disclosed in U.S. Patent No. 4,848,289 in 1989 a braking method that uses an exhaust brake to increase exhaust back pressure and cause a floating valve.

Sweden's Volvo (Volvo) disclosed a combined braking method in which a compression release type engine brake and an exhaust brake are used together in US Patent No. 5,146,890 in 1992. Among them, the brake cam of the engine has increased the exhaust gas recirculation (EGR) boss in addition to the compression release brake boss. The exhaust valve opens at the later stage of the intake stroke, and the high back pressure exhaust gas (air during braking) generated by the exhaust brake reversely charges the engine cylinder from the exhaust pipe to increase the compression braking power.

In 1997, U.S. Patent No. 5,692,469 by Rammer of MAN disclosed a device and method for using an exhaust brake to increase the exhaust back pressure to cause a floating valve (valve bounce) and then open a leaking brake. . When the exhaust back pressure is high enough, the exhaust valve floats or bounces toward the end of the intake stroke. During the floating period of the exhaust valve, it is intervened by a braking device, that is, before the floating exhaust valve is closed, it is intercepted by an oil pressure-controlled piston, preventing it from closing and keeping it small. The volume is constantly open, resulting in partial cycle bleed braking (the exhaust valve is closed after the exhaust stroke). The braking system is for engines with a single exhaust valve per cylinder. In 2006, Rammer et al. extended the above technology to an engine with double exhaust valves per cylinder (US Patent No. 7013867, Chinese Patent No. 200310123153.7).

The reliability and durability of the above-mentioned vented engine braking system of MAN faced many problems because it relied on the intermittent opening or floating of the brake exhaust valve, which was inconsistent both in time and magnitude . It is well known that the floating height of the exhaust valve depends on the exhaust back pressure, which depends on the engine speed and is affected by the quality and control of the exhaust brake and the design of the exhaust system. At medium and low engine speeds, the float of the exhaust valve may be insufficient or not at all, and the engine braking device may not be activated. At this time, the demand for engine braking is high, because commercial vehicle engines run at medium and low speeds most of the time. In addition, excessive exhaust back pressure not only floats the braked exhaust valve, but also floats the unbraked exhaust valve. The seating speed of an unbraked exhaust valve will be too high, affecting the reliability and durability of the engine.

In 2010, the inventor disclosed in US Patent No. 7673600 (Chinese Patent Application Publication No. CN1991136A) a part-period deflated brake device and method generated by cam driving. The main and auxiliary pistons are integrated in the valve bridge of the engine. There is a one-way oil supply valve in the main piston, and another brake one-way valve is also arranged in the hydraulic flow channel between the main piston and the auxiliary piston. The brake cams are integrated with the engine's regular exhaust cams, including deflated-type brake bosses. The deflated brake boss begins to rise from the inner base circle of the cam late in the engine intake stroke. Rise to top lift near bottom dead center on the intake stroke, then hold that top lift constant during the engine's compression and expansion strokes, before transitioning smoothly into the conventional exhaust boss. When the engine brakes, instead of relying on the exhaust back pressure to raise the floating exhaust valve to open the brake, the brake boss pushes the main piston in the valve bridge, and the main piston drives the auxiliary piston to open the exhaust valve. The brake check valve is locked in the extended position, holding the exhaust valve a small amount of constant opening, producing part cycle deflated type braking.

The brake drive mechanisms of many of the brake devices mentioned above are integrated in the valve bridge of the engine. A precedent for a valve bridge brake is disclosed in US Patent No. 3,520,287 in 1970 by Calvin. The entire valve bridge is sleeved on a central guide rod. There are brake oil passages and control valves inside the guide rod. The upper part of the guide rod acts as a brake piston, and the valve bridge slides along the brake piston through the piston hole inside it.

An improved valve bridge braking mechanism was disclosed by Sickler in US Patent No. 4,572,114 in 1986. A dedicated brake piston is placed in the upwardly opened piston hole in the center of the valve bridge, which greatly reduces the relative movement between the brake piston and the valve bridge. This bridge brake mechanism is used on four-stroke engines, but produces two compression release brakes per cycle.

The bridge brake device (referring to U.S. Patent Publication No. US 20050211206, the inventor is one of the inventors of this patent application) designed and manufactured by JVS (JVS) in South Korea Hyundai (Hyundai) in Sikele ( Sickler) added a valve lift reset mechanism on the basis of the valve bridge braking mechanism. In addition, one to three pistons can be arranged in the valve bridge, and one or two exhaust valves can be opened during braking.

In 2007, Huang, the inventor and Schwoerer disclosed in U.S. Patent No. 7284533 (Chinese Patent Application Publication No. CN101490393A) that a brake cam profile is used to realize brake design requirements and optimization. method of the braking function.

Invention content:

The object of the present invention is to provide a compression release type engine braking method, which will solve the problems of poor reliability and durability, installation and maintenance of the engine braking mechanism in the prior art. Inconvenient commissioning and technical problems of increased engine height and weight.

The compression release type engine braking method of the present invention includes a process of using the exhaust valve drive chain of the engine to open the exhaust valve. The exhaust valve drive chain includes a cam, a rocker arm and a valve bridge. The engine The exhaust valve includes a first exhaust valve and a second exhaust valve, and the cam contains at least one brake boss, and the brake boss includes a rising from the inner base circle of the cam The ascending section to the maximum lift and the same height section maintaining the maximum lift, an oil supply channel is arranged in the rocker arm, wherein a main piston is opened upward in the center of the valve bridge A secondary piston hole is opened downward at one end of the valve bridge, a hydraulic channel is connected between the primary piston hole and the secondary piston hole, a primary piston is slidably set in the primary piston hole, and the primary piston There is an extended position and a retracted position relative to the main piston hole, and an auxiliary piston is slidably arranged in the auxiliary piston hole, the upper end of the main piston is connected with the rocker arm, and an oil passage is arranged in the main piston , communicate the upper end of the oil passage with the oil supply channel in the rocker arm, communicate the lower end of the oil passage with the main piston hole, between the main piston hole and the oil supply passage, or between the oil supply passage A one-way oil supply valve is arranged inside, the oil supply direction of the one-way oil supply valve is from the oil supply channel to the main piston hole, connect the lower end of the auxiliary piston with the first exhaust valve, and connect the valve bridge The lower side of the other end is connected with the second exhaust valve, and a brake bracket is set on the upper side of the valve bridge end where the auxiliary piston hole is located, and the exhaust valve is opened by the exhaust valve drive chain of the engine. In the process, first, oil is supplied to the main piston hole through the oil supply passage and the one-way oil supply valve, the main piston is placed in the extended position, and the hydraulic passage between the main piston hole and the auxiliary piston hole is opened, and then , using the rising section of the brake boss in the cam to drive the rocker arm, so that the rocker arm pushes the main piston to move from the extended position to the retracted position, and at the same time, the brake bracket is used to prevent the valve bridge from moving upwards, and the valve bridge is used to move upward. The hydraulic pressure in the above-mentioned hydraulic channel transmits the movement of the main piston to the auxiliary piston, forcing the auxiliary piston to protrude downward in the auxiliary piston hole, opening the first exhaust valve, and then using the brake boss in the cam, etc. The high section drives the rocker arm, keeps the main piston in the retracted position in the main piston hole, blocks the hydraulic transmission between the main piston hole and the auxiliary piston hole through the hydraulic channel, and keeps the auxiliary piston in the auxiliary piston hole In the protruding position, the first exhaust valve is kept open, and at the same time, the brake bracket is used to carry the brake load on the auxiliary piston.

Further, at least one oil unloading passage is set in one end of the valve bridge where the auxiliary piston hole is located, the lower end of the oil unloading passage is communicated with the auxiliary piston hole, and the upper end of the oil unloading passage is closed by the lower end of the brake bracket Open your mouth.

Further, a descending section is set on the braking boss, the starting point of the descending section is connected to the end of the contour section, and the end point of the descending section is returned to or close to the inner base circle of the cam .

Further, when the brake boss in the cam passes through the contour section and enters the descending section, the rocker arm is used to perform reverse movement, so that the main piston moves from the retracted position to the extended position, and the hydraulic channel is opened in the main piston. The opening on the hole is connected to the hydraulic transmission between the main piston hole and the auxiliary piston hole, so that the auxiliary piston moves to the retracted position under the force of the first exhaust valve.

Further, the oil passage in the main piston is arranged along the axial direction of the main piston, and the lower end opening of the oil passage is arranged in the lower end surface of the main piston.

Alternatively, an integrated exhaust boss is set on the cam, a slow-rising section is set on the braking boss, and the starting point of the slow-rising section is connected to the end of the equal-height section , merge the end point of the slow-rising section into the integrated exhaust boss, and use the slow-rising section of the braking boss to drive The rocker arm pushes the valve bridge downward through the main piston located in the retracted position in the main piston hole, so that one end of the valve bridge where the auxiliary piston hole is located is separated from the brake bracket located on its upper side , open the upper opening of the oil discharge channel to discharge oil, reduce the hydraulic pressure in the auxiliary piston hole, and make the auxiliary piston move upward to the retracted position in the auxiliary piston hole under the force of the first exhaust valve, so that the first exhaust valve Move up to the closed position.

Further, the process of using the exhaust valve driving chain of the engine to open the exhaust valve includes the following steps:

1) Open the brake control mechanism of the engine, supply oil to the main piston hole in the valve bridge through the oil supply channel and the one-way oil supply valve,

2) The main piston is placed in the extended position in the main piston hole, and the hydraulic channel between the main piston hole and the auxiliary piston hole in the valve bridge is opened,

3) The auxiliary piston is in the retracted position in the auxiliary piston hole, and the first exhaust valve under the auxiliary piston is in the closed position,

4) The braking boss of the cam moves upward from the inner base circle, driving the main piston in the main piston hole to move down to the retracted position in the main piston hole of the valve bridge,

5) The brake bracket on the valve bridge above the auxiliary piston hole prevents or restricts the upward movement of the valve bridge,

6) The downward movement of the main piston is transmitted to the auxiliary piston through the hydraulic channel, and the auxiliary piston in the auxiliary piston hole of the valve bridge moves downward to the extended position to open the first exhaust valve,

7) The brake boss of the cam reaches the highest lift and continues to maintain the highest lift position,

8) The main piston reaches the retracted position downward in the main piston hole of the valve bridge, closing the hydraulic channel between the main piston hole and the auxiliary piston hole, preventing the hydraulic load on the auxiliary piston from being transmitted to the main piston,

9) The auxiliary piston reaches the extension position downward in the auxiliary piston hole of the valve bridge, and keeps the first exhaust valve under the auxiliary piston open at the highest brake valve lift position,

10) Use the brake bracket on the upper side of the valve bridge where the auxiliary piston hole is located to support the load transmitted from the first exhaust valve to the auxiliary piston,

11) The braking boss of the cam descends from the highest lift back to the inner base circle,

12) The main piston moves upward from the retracted position in the main piston hole of the valve bridge back to the extended position, opening the hydraulic channel between the main piston hole and the auxiliary piston hole,

13) The auxiliary piston moves upward from the extended position in the auxiliary piston hole to the retracted position,

14) The first exhaust valve moves upward from the highest brake valve lift position to the closed position.

Further, the process of using the exhaust valve driving chain of the engine to open the exhaust valve also includes the following steps:

1) Turn off the brake control mechanism of the engine, stop supplying oil to the main piston hole in the valve bridge,

2) The cam drives the main piston in the main piston hole of the valve bridge to move downward,

3) The main piston drives the valve bridge to move downward, and the end of the valve bridge where the auxiliary piston hole is located is separated from the brake bracket on the upper side.

4) Open the oil unloading channel above the auxiliary piston hole to unload oil,

5) The auxiliary piston moves from the auxiliary piston hole of the valve bridge to the retracted position.

Further, when the main piston slides from the retracted position to the extended position in the main piston hole, the main piston is used to open the opening of the hydraulic channel on the main piston hole, and the main piston slides from the extended position to the main piston hole in the main piston hole. In the retracted position, the opening of the hydraulic channel on the bore of the main piston is closed by the main piston.

Further, the oil unloading channel is provided with an outlet, and when the valve bridge is moved downwards driven by the cam, the valve bridge is separated from the brake bracket, and the outlet of the oil unloading channel is opened.

Further, the brake bracket is fixed on the engine, the brake bracket includes a connecting piece, and the connecting piece is located above the valve bridge.

Further, the brake bracket is integrated on the rocker arm, the brake bracket includes a connecting piece, and the connecting piece is located above the valve bridge.

Further, the brake boss includes a compression release boss, and the compression release boss starts to rise from the inner base circle of the cam at the later stage of the compression stroke of the engine, and is near the compression top dead center of the engine. Reaching the highest position, it descends back to the inner base circle of the cam early in the engine's expansion stroke.

Further, the brake boss includes a compression release boss and an exhaust gas recirculation boss, and the compression release boss rises from the inner base circle of the cam at the later stage of the compression stroke of the engine, and It reaches the highest position near the compression top dead center of the engine, and descends back to the inner base circle of the cam in the early stage of the expansion stroke of the engine. The circle begins to rise and descends back to the inner base circle of the cam early in the engine's compression stroke.

Further, an integrated exhaust boss is set on the cam, and the brake boss includes a compression release boss, and the compression release boss is released from the cam at the later stage of the compression stroke of the engine. The inner base circle begins to rise and rises to the highest position before the top dead center of the engine's compression stroke, and maintains the said highest position during the remainder of the engine's compression stroke and the beginning of the engine's expansion stroke During this period, it descends back to the inner base circle of the cam or merges into the integrated exhaust boss, which is composed of the bottom and the top, and the bottom of the integrated exhaust boss is close to the same height as the brake boss , the top of the integrated exhaust boss is nearly identical to the engine's regular boss.

Further, the brake boss includes an exhaust gas recirculation boss, and the exhaust gas recirculation boss starts to rise from the inner base circle of the cam at the later stage of the intake stroke of the engine. The early part of the stroke drops back to the inner base circle of the cam.

Further, an integrated exhaust boss is set on the cam, and the brake boss includes a compression release boss, and the compression release boss releases from the cam in the latter half of the compression stroke of the engine. The inner base circle of the engine starts to rise, and rises to the highest position before the compression top dead center of the engine, and maintains the highest position during the remaining period of the compression stroke of the engine and the early stage of the expansion stroke of the engine, during the remainder of the expansion stroke of the engine The period rises into the integrated exhaust boss.

Further, a pre-tension spring is used to maintain the exhaust valve drive chain brake gap generated by the retracted position and extended position of the main piston inside the exhaust valve drive chain, and the exhaust valve drive chain brake gap is used to Eliminates non-following and jerk inside the exhaust valve drive chain.

The present invention also provides a compression-release engine brake device, which includes a brake control mechanism and a brake drive mechanism, wherein the brake control mechanism includes a The control valve connected to the hydraulic pressure generation device, the brake drive mechanism includes a brake box, an oil supply mechanism, an oil discharge mechanism and a brake cam. The brake box is provided with a main piston hole and a secondary piston hole. A communicating hydraulic passage is provided between the main piston hole and the auxiliary piston hole, the main piston is slidably arranged in the main piston hole, and the auxiliary piston is slidably arranged in the auxiliary piston hole, and the oil supply mechanism includes a An oil passage and a one-way oil supply valve, the control valve in the brake control mechanism is connected to the inlet of the oil supply passage, the outlet of the oil supply passage is connected to the main piston hole, and the one-way oil supply valve It is arranged in the oil supply channel or between the oil supply channel and the main piston hole. The oil supply direction of the one-way oil supply valve is from the oil supply channel to the main piston hole. The oil unloading mechanism includes an oil unloading valve. The oil unloading valve communicates with the secondary piston hole, and the braking cam contains at least one braking boss.

Further, the brake box is composed of a valve bridge, the main piston hole is set in an upward opening in the center of the valve bridge, and the auxiliary piston hole is set in an upward opening at one end of the valve bridge. In the lower opening, the hydraulic passage is arranged in the valve bridge and communicates with the main piston hole and the auxiliary piston hole, the main piston is arranged in the main piston hole, the auxiliary piston is arranged in the auxiliary piston hole, and the main piston The upper end of the upper end is fixedly connected with the rocker arm of the engine. An oil supply passage is arranged in the rocker arm, and an oil passage is arranged in the main piston. The upper end of the oil passage is connected with the oil supply passage in the rocker arm. The lower end of the oil circuit communicates with the main piston hole. The one-way oil supply valve is arranged between the main piston hole and the oil supply channel or in the oil supply channel. The oil supply direction of the one-way oil supply valve From the oil supply channel to the main piston hole, a brake bracket is provided on the upper side of the valve bridge where the auxiliary piston hole is located, and at least one oil discharge channel is provided at the end of the valve bridge where the auxiliary piston hole is located. One end communicates with the auxiliary piston hole, the other end of the oil discharge channel is closed by the lower end of the brake bracket, and the brake cam is provided with an integrated exhaust boss.

Further, the lower end of the auxiliary piston is connected with a first exhaust valve of the engine exhaust valve, and the lower side of the other end of the valve bridge is connected with a second exhaust valve of the engine exhaust valve.

Further, the brake bracket is fixed on the engine, and the brake bracket includes a connecting piece, and the connecting piece is located above the valve bridge.

Further, the brake bracket is integrated on the rocker arm, and the brake bracket includes a connecting piece, and the connecting piece is located above the valve bridge.

Further, the connecting piece of the brake bracket includes a transition piston, and the transition piston is slidably arranged in the transition piston hole of the valve bridge, and the transition piston hole is located above the auxiliary piston hole.

Further, the brake boss includes a compression release boss, and the compression release boss starts to rise from the inner base circle of the cam at the later stage of the compression stroke of the engine, and is near the compression top dead center of the engine. The highest position is reached, falling back to or near the inner base circle of the cam early in the engine's expansion stroke.

Further, the brake boss includes a compression release boss and an exhaust gas recirculation boss, and the compression release boss rises from the inner base circle of the cam at the later stage of the compression stroke of the engine, and It reaches the highest position near the compression top dead center of the engine, and falls back to or close to the inner base circle of the cam in the early stage of the engine's expansion stroke, and the exhaust gas recirculation boss is removed from the cam's in the late stage of the engine's intake stroke The inner base circle begins to rise and falls back to the inner base circle of the cam early in the compression stroke of the engine.

Further, an integrated exhaust boss is provided on the cam, and a compression release boss is included in the brake boss, and the compression release boss releases from the cam at the later stage of the compression stroke of the engine. The inner base circle of the engine starts to rise and rises to the highest position before the top dead center of the engine's compression stroke, and maintains the said highest position during the remainder of the engine's compression stroke and the initial stage of the engine's expansion stroke. During the remaining period, it descends back to the inner base circle of the cam or merges into the integrated exhaust boss, which consists of a bottom and a top, and the bottom of the integrated exhaust boss is nearly the same as the brake boss Tall, the tops of the integrated exhaust bosses are nearly identical to the engine's regular bosses.

Further, the brake boss includes an exhaust gas recirculation boss, and the exhaust gas recirculation boss starts to rise from the inner base circle of the cam at the later stage of the intake stroke of the engine. The early part of the stroke drops back to the inner base circle of the cam.

Further, an integrated exhaust boss is provided on the cam, and the brake boss includes a compression release boss, and the compression release boss starts from The inner base circle of the cam starts to rise and rises to the highest position before the compression top dead center of the engine, and maintains the said highest position during the remainder of the compression stroke of the engine and the early stage of the expansion stroke of the engine. The rest of the period rises into the integrated exhaust boss.

Further, a pre-tension spring is arranged in the brake driving mechanism.

Further, one end of the pre-tension spring is arranged on the engine, and one end of the pre-tension spring acts on one end of the rocker arm.

Still further, an automatic backlash compensation mechanism is set in the brake drive mechanism.

The working principle of the present invention is: when engine braking is required, the brake control mechanism is opened to supply oil to the brake drive mechanism. Low-pressure engine oil (engine lubricating oil) enters the main piston hole from the oil supply channel and the one-way oil supply valve, and the main piston is in the extended position in the main piston hole of the valve bridge, opening the hydraulic pressure between the main piston hole and the auxiliary piston hole. aisle. The braking boss of the cam rises from the inner base circle, and the rocker arm drives the main piston in the valve bridge to move down from the extended position to the retracted position on the bottom surface of the main piston hole, and the downward movement of the main piston is transmitted to the valve through the hydraulic channel. vice piston. The brake support on the valve bridge above the auxiliary piston hole prevents the valve bridge from rising due to the oil pressure in the auxiliary piston hole. The auxiliary piston in the auxiliary piston hole of the valve bridge protrudes downwards to open the brake exhaust valve located under the auxiliary piston. When the cam enters the highest lift of the brake boss, the main piston reaches the retracted position at the bottom of the hole in the main piston hole of the valve bridge, blocks the entrance of the hydraulic channel, and closes the hydraulic channel between the main piston hole and the auxiliary piston hole . The auxiliary piston reaches the extended position downward in the auxiliary piston bore of the valve bridge, keeping the exhaust valve below the auxiliary piston open for a gap. The braking load on the auxiliary piston cannot be transmitted to the main piston through the hydraulic channel, but can only be transmitted to the brake bracket located on the valve bridge above the auxiliary piston hole through the valve bridge. At this time, neither the main piston nor the exhaust valve actuator (including rocker arm and cam, etc.) bears the braking load. When the cam descends from the highest lift of the brake boss, the main piston moves upward from the retracted position in the main piston hole of the valve bridge to the extended position, opening the hydraulic passage between the main piston hole and the auxiliary piston hole, and the auxiliary piston hole The auxiliary piston in the piston bore moves upward together with the main piston. The main piston returns upwards to the extended position in the main piston hole of the valve bridge, the auxiliary piston returns upwards to the retracted position in the auxiliary piston hole of the valve bridge, and the exhaust valve below the auxiliary piston moves upwards to the closed position.

The integrated exhaust boss of the cam rises from the inner base circle, the rocker arm drives the main piston in the valve bridge to move down from the extended position to the retracted position on the bottom surface of the main piston hole, and the downward movement of the main piston passes through the hydraulic channel Passed to the secondary piston. The brake support on the valve bridge above the auxiliary piston hole prevents the valve bridge from rising due to the oil pressure in the auxiliary piston hole. The auxiliary piston in the auxiliary piston hole of the valve bridge protrudes downwards to open the brake exhaust valve located under the auxiliary piston. The cam enters the top of the integrated exhaust boss, and the main piston presses the bottom of the main piston hole, driving the valve bridge to move downward. The valve bridge is separated from the brake bracket on it, and the oil unloading channel above the auxiliary piston hole in the valve bridge is opened to discharge oil, and the auxiliary piston moves from the extended position to the retracted position in the auxiliary piston hole of the valve bridge. The valve bridge transfers the movement of the top of the integrated exhaust boss to the two exhaust valves, resulting in conventional exhaust valve movement.

Compared with the prior art, the present invention has positive and obvious effects. The invention integrates the compression release type brake mechanism inside the existing valve drive chain of the engine, and uses the brake bracket to bear the brake load and reset the brake valve lift. The design is simple, the structure is compact, and the braking force of the engine is reduced. Load, increased braking power of the engine, improved reliability and durability of engine operation.

Description of drawings:

Fig. 1 is a schematic diagram of the first embodiment of the compression-release engine braking device of the present invention when the cam is at the position of the inner base circle during braking.

Fig. 2 is a schematic diagram of the first embodiment of the compression release engine braking device of the present invention when the cam is at the highest position of the braking boss during braking.

Fig. 3 is a schematic diagram of the brake control mechanism of the compression release engine brake device in the present invention in the "on" position.

Fig. 4 is a schematic diagram of the brake control mechanism of the compression release engine brake device in the present invention in the "off" position.

Fig. 5 is a schematic diagram of a cam profile of the compression release type engine braking device in the present invention.

FIG. 6 is a schematic diagram of an exhaust valve lift curve and an intake valve lift curve of the compression release type engine braking device in the present invention.

Fig. 7 is a schematic diagram of yet another cam profile of the compression release engine braking device of the present invention.

Fig. 8 is a schematic diagram of yet another cam profile of the compression release engine braking device of the present invention.

Fig. 9 is a schematic diagram of the second embodiment of the compression-release engine braking device of the present invention when the cam is at the position of the inner base circle when not braking.

Fig. 10 is a schematic diagram of the second embodiment of the compression release engine braking device in the present invention when the cam is at the position of the inner base circle during braking.

Detailed ways:

Example 1:

As shown in FIG. 1 and FIG. 2 , the first embodiment of the compression release engine braking device of the present invention, the cam 230 is respectively at the position of the inner base circle 225 and the highest lift position of the braking boss during braking. 1 and 2 include three main components: an exhaust valve actuator 200 , an exhaust valve 300 (including a first exhaust valve 3001 and a second exhaust valve 3002 ) and an engine braking drive mechanism 100 .

Exhaust valve actuator 200 includes cam 230 , cam follower 235 , rocker arm 210 and valve bridge 400 . Collectively, exhaust valve actuator 200 and exhaust valve 300 may be referred to as an exhaust valve drive train. Usually, one end of the rocker arm 210 (the side close to the valve bridge 400 or the side close to the cam 230 ) is provided with a valve clearance adjustment system. The valve gap adjusting system in this embodiment is composed of a valve gap adjusting screw 110 arranged on one side of the valve bridge 400 , and the valve gap adjusting screw 110 is located on the rocker arm 210 and fixed by a locking nut 105 . Valve gap adjusting screw 110 links to each other with elephant foot pad 114. The rocker arm 210 is swingably mounted on the rocker shaft 205 .

The first exhaust valve 3001 and the second exhaust valve 3002 are respectively pushed on the valve seat 320 in the engine block 500 by the valve spring 3101 and the valve spring 3102 (referred to as the valve spring 310), preventing the gas (when the engine brakes, air) between the engine cylinders and the exhaust pipe 600. The exhaust valve actuator 200 transmits the mechanical motion of the cam 230 to the first exhaust valve 3001 and the second exhaust valve 3002 through the valve bridge 400 to make them open and close periodically.

The brake driving mechanism 100 includes a brake box, a brake bracket and a brake cam. The brake case in this embodiment adopts the valve bridge 400 of the engine. The central opening of the valve bridge 400 is provided with a main piston hole 415 , and one end of the valve bridge 400 is opened downward and is provided with a secondary piston hole 190 . The primary piston hole 415 and the secondary piston hole 190 are connected by a hydraulic channel 412 . The main piston hole 415 is also connected to the oil supply passage 115 above it through the one-way oil supply valve 172 . A primary piston 162 and a secondary piston (also called brake piston) 160 are slidably disposed in the primary piston hole 415 and the secondary piston hole 190 respectively. The upper face of the main piston 162 is acted upon by the rocker arm 210 . The lower side of the auxiliary piston 160 is connected with the first exhaust valve 3001 of the engine which can act as a brake. The lower side of the other end of the valve bridge 400 is connected with the second exhaust valve 3002 of the engine without braking. An oil unloading passage 197 is arranged in the valve bridge 400 above the auxiliary piston hole 190 , and the oil unloading passage 197 communicates with the auxiliary piston hole 190 , and a brake bracket 125 is arranged above the oil unloading passage 197 . Brake bracket 125 includes adjustable connectors 1052 and 1142 and fastener 1102 . The brake bracket 125 can be fixed on the engine. The brake bracket 125 is located (via a connecting piece) on the valve bridge 400 above the secondary piston bore 190 and closes the outlet of the oil discharge channel 197 . The brake cam is integrated with the normal cam of the engine, the integrated cam 230 has at least one brake boss and integrated exhaust boss 220 thereon. The detent bosses of the cam 230 here include a compression release boss 233 and an exhaust gas recirculation boss 232 on the inner base circle 225 .

A preload spring 198 may be arranged between the exhaust rocker arm 210 and the engine. In this embodiment, the pre-tension spring 198 is a leaf spring, one end of which is placed on the brake bracket 125 , and the other end is placed on the rocker arm 210 . The pretension spring 198 may be a coil spring or other types of springs.

The preload spring 198 can also be installed in different ways, such as between the main piston 162 and the valve bridge 400, between the cam 230 (or the push rod of the push rod engine) and the rocker arm 210, etc. The preload spring 198 maintains the braking gap 234 generated inside the exhaust valve drive chain by the retracted position ( FIG. 2 ) and the extended position ( FIG. 1 ) of the main piston 162 (this gap can be moved by the cam 230 when not braking). between the inner base circle 225 and the cam follower 235), eliminating non-following and shock inside the exhaust valve drive chain.

A positioning pin 137 is provided in the valve bridge 400 , and a limiting groove 142 is provided in the auxiliary piston 160 to form a piston limiting mechanism to limit the maximum stroke of the auxiliary piston 160 . A spring 177 may be arranged between the secondary piston 160 and the valve bridge 400 .

In this embodiment, a pressure relief mechanism is also provided in the valve bridge 400 . The pressure relief mechanism includes a pressure relief hole 152 on the auxiliary piston 160 . When the oil pressure in the auxiliary piston hole 190 increases, the oil leakage through the gap between the auxiliary piston 160 and the hole 190 and the positioning groove 137 on the brake piston 160 and the pressure relief hole 152 increases accordingly, so that the oil pressure on the auxiliary piston 160 increases. The oil pressure on the piston 160 does not exceed the designed predetermined value.

When engine braking is required, as shown in Figure 3, the brake control mechanism 50 is turned on. Oil is supplied to the brake drive mechanism 100 through a brake fluid network. The brake fluid network includes numerous oil supply passages, such as the axial hole 211 and radial hole 212 in the rocker shaft 205, the cutout 213 and the oil hole 214 in the rocker arm 210, and the transverse hole 113 in the valve gap adjustment screw. And vertical hole 115 (communicates with like the hole in foot pad 114). The low-pressure engine oil is supplied to the main piston hole 415 from the oil supply passage through the one-way oil supply valve 172 provided on the main piston 162 . The main piston 162 is in the protruding position shown in Figure 1 in the main piston hole 415 of the valve bridge 400, and a brake gap is formed between the main piston 162 and the bottom surface 446 of the main piston hole 415 (that is, the valve bridge 400). 234, the hydraulic channel 412 between the primary piston hole 415 and the secondary piston hole 190 is in an open position.

For clarity, the engine's lubricating oil passages are not shown here. Of course, the lubricating oil passage can also be combined with the brake oil passage, and two stages of different oil pressures are used for oil supply. Use low oil pressure for lubrication, say one bar or less and high oil pressure for braking, say two bar or more.

When the brake boss (compression release boss) 233 of the cam 230 rises from the inner base circle 225, the rocker arm 210 drives the main piston 162 in the valve bridge 400 to move down from the extended position in FIG. 1 to the main piston hole. The retracted position of the bottom surface 446 transmits the downward movement of the primary piston 162 to the secondary piston 160 through the hydraulic passage 412 between the primary piston bore 415 and the secondary piston bore 190 . The brake bracket 125 on the valve bridge 400 above the auxiliary piston hole 190 prevents the valve bridge 400 from rising due to the oil pressure in the auxiliary piston hole 190 . The auxiliary piston 160 in the auxiliary piston hole 190 of the valve bridge 400 can only extend downwards to open the braking first exhaust valve 3001 located below the auxiliary piston 160 . When the cam 230 enters the highest lift of the braking boss 233, the main piston 162 reaches the retracted position (Fig. 2) at the bottom of the hole 446 in the main piston hole 415 of the valve bridge 400, blocking the inlet 472 of the hydraulic passage 412. , close the hydraulic channel 412 between the primary piston hole 415 and the secondary piston hole 190 . At the same time, the auxiliary piston 160 reaches the extension position downward in the auxiliary piston hole 190 of the valve bridge 400 , the stroke of the auxiliary piston 160 is 130 , and the first exhaust valve 3001 below the auxiliary piston 160 opens a gap 330 accordingly. At this time, the braking load on the secondary piston 160 cannot be transmitted to the primary piston 162 through the hydraulic channel 412 , but can only be transmitted to the brake bracket 125 on the valve bridge 400 above the secondary piston hole 190 through the valve bridge 400 . Neither the main piston 162 nor the exhaust valve actuator 200 (including the rocker arm 210 and the cam 230 ) are subjected to braking loads. When the cam 230 descends from the highest lift of the brake boss 233, the primary piston 162 moves upward from the retracted position in the primary piston bore 415 of the valve bridge 400 to the extended position, opening the primary piston bore 415 and the secondary piston bore. 190 , the secondary piston 160 in the secondary piston hole 190 moves upward together with the primary piston 162 . As the primary piston 162 returns upwardly to the extended position within the primary piston bore 415 of the valve bridge 400 , the secondary piston 160 returns upwardly to the retracted position within the secondary piston bore 190 of the valve bridge 400 ( FIG. 1 ).

When the integrated exhaust boss 220 of the cam 230 rises from the inner base circle 225, the rocker arm 210 drives the main piston 162 in the valve bridge 400 to move downward from the extended position in FIG. Back to the position, the downward movement of the primary piston 162 is transmitted to the secondary piston 160 through the hydraulic channel 412 between the primary piston hole 415 and the secondary piston hole 190 . The brake bracket 125 on the valve bridge 400 above the auxiliary piston hole 190 will not rise due to the oil pressure in the auxiliary piston hole 190 . The auxiliary piston 160 in the auxiliary piston hole 190 of the valve bridge 400 can only extend downwards to open the first exhaust valve 3001 located below the auxiliary piston 160 . When the cam 230 enters the top of the integrated exhaust boss 220 (greater than the highest lift of the brake boss 233), the main piston 162 presses the bottom 446 of the main piston hole, driving the valve bridge 400 to move downward. The valve bridge 400 is separated from the brake bracket 125 on it, and the oil unloading passage 197 in the valve bridge 400 communicated with the auxiliary piston hole 190 is opened to unload the oil, and the auxiliary piston 160 is released from the extended position in the auxiliary piston hole 190 of the valve bridge 400. Move to the retracted position. The valve bridge 400 transmits the movement of the top of the integrated exhaust boss 220 to the first exhaust valve 3001 and the second exhaust valve 3002, resulting in conventional exhaust valve movement.

If the detent boss of the cam 230 also includes the exhaust gas recirculation boss 232, then the process of the exhaust gas recirculation boss 232 opening the first exhaust valve 3001 through the exhaust valve driving chain is the same as the above-mentioned compression release boss 233 The process of opening the first exhaust valve 3001 through the exhaust valve driving chain is the same and will not be repeated here. If the engine has sufficient exhaust back pressure, then after increasing the exhaust gas recirculation boss 232, the braking power of the engine may be further improved.

When engine braking is not required, as shown in FIG. 4 , the brake control mechanism 50 is turned off, and oil supply to the brake drive mechanism 100 is stopped. When the cam 230 enters the top of the integrated exhaust boss 220 (greater than the highest lift of the compression release boss 233), the main piston 162 presses the bottom 446 of the main piston hole, driving the valve bridge 400 to move downward. The valve bridge 400 is separated from the brake bracket 125 on it, and the oil unloading passage 197 in the valve bridge 400 communicated with the auxiliary piston hole 190 is opened to unload the oil, and the auxiliary piston 160 is released from the extended position in the auxiliary piston hole 190 of the valve bridge 400. (Picture 2) to the retracted position (Picture 1). The valve bridge 400 transmits the movement of the top of the integrated exhaust boss 220 to the first exhaust valve 3001 and the second exhaust valve 3002, resulting in conventional exhaust valve movement. As the cam 230 goes from the top of the integrated exhaust boss 220 to its bottom and back to the inner base circle, the secondary piston 160 remains in the retracted position shown in FIG. 1 (due to the upward force of the exhaust valve spring 3101) , the main piston 162 remains in the retracted position shown in FIG. 2 (due to the downward force of the preload spring 198), a gap is formed between the cam follower 235 on the rocker arm 210 and the inner base circle 225 of the cam 230. Due to this clearance, the movement of the detent bosses (compression release boss 233 and exhaust gas recirculation boss 232) will not be transferred to the exhaust valve 300, only the movement of the top of the integrated exhaust boss 220 will be transferred to the exhaust The valve 300 produces conventional exhaust valve movement, and the braking operation of the engine is released.

As shown in FIG. 3 and FIG. 4 , the brake control mechanism 50 of the compression release engine brake device of the present invention is in the "on" and "off" positions. The solenoid valve 51 in the figure is a two-position three-way type. When the brake control mechanism 50 is opened (Fig. 3), the valve body of the solenoid valve 51 opens the oil supply port 111 downwards, and at the same time closes the oil discharge port 222, and the low-pressure engine oil (lubricating oil) of the engine flows from the brake fluid passage to the brake valve. Drive mechanism 100 (FIGS. 1 and 2). When the brake control mechanism 50 is closed (Fig. 4), the valve body of the electromagnetic valve 51 closes the oil supply port 111 upwards, and simultaneously opens the oil discharge port 222, and the low-pressure machine oil (lubricating oil) of the engine stops flowing to the brake drive mechanism 100 (Fig. 1 and FIG. 2 ), the brake drive mechanism 100 discharges oil from the brake fluid passage and the oil discharge port 222 instead. Since the auxiliary piston hole 190 in the valve bridge 400 is provided with an oil discharge channel 197 ( FIGS. 1 and 2 ), it is entirely possible to use a two-position two-way solenoid valve, that is, the oil discharge port 222 is not required.

Figure 5 shows a cam profile in the compression release engine braking device of the present invention, which includes a brake boss and an integrated exhaust boss 220, the brake boss includes a compression release boss 233 and an exhaust gas Recirculation boss 232 . The compression release boss 233 includes three sections: an ascending section "A", a contour section "B" and a descending section "C". Rising segment "A" rises from the inner base circle 225 of the cam to the highest lift of the brake. Contour section "B" keeps the maximum lift of the brake essentially constant over a period of time. The descending segment "C" descends from the highest lift of the brake back to the inner base circle 225 of the cam. The function of the contour section "B" is to keep the main piston 162 in the retracted position of the hole bottom 446 in the main piston hole 415 of the valve bridge 400 during braking (Fig. 2), and close the main piston hole 415 and the auxiliary piston hole 190 Between the hydraulic channel 412 , the braking load on the secondary piston 160 cannot be transmitted to the primary piston 162 through the hydraulic channel 412 , but can only be transmitted to the brake bracket 125 located thereon through the valve bridge 400 . In this way, the exhaust valve actuator 200 (including the rocker arm 210 and the cam 230 ) does not bear the braking load, which reduces the force and wear of the exhaust valve actuator 200 and increases the reliability and durability of the engine.

The exhaust gas recirculation boss 232 may also be designed in the shape of the compression release boss 233 . However, during exhaust gas recirculation, the force on the exhaust valve is much less than during compression release. Therefore, the design of the contour curve shape of the exhaust gas recirculation boss 232 may not consider the influence of the load.

The integrated exhaust boss 220 is divided into a bottom and a top (the two-dashed line in FIG. 5 separates them). The bottom of the integrated exhaust boss 220 is a transition part, which is close to the same height as the brake boss; the top of the integrated exhaust boss 220 is nearly the same as the conventional boss of the engine. Thus, during non-braking (normal ignition) operation, the movement of the bottom of the integrated exhaust boss 220 along with the braking boss (compression release boss 233 and exhaust gas recirculation boss 232) is due to exhaust valve actuation. The gap 234 (FIG. 1) inside the chain is skipped or lost and is not transmitted to the exhaust valve 300; only the movement of the top of the integrated exhaust boss 220 is transmitted to the exhaust valve 300, resulting in a regular valve lift movement .

FIG. 6 shows a lift curve of an exhaust valve and a lift curve of an intake valve in the compression release type engine braking device of the present invention. The conventional valve lift curve 220m of the engine exhaust valve starts at 225a, ends at 225b, and has a maximum lift of approximately 220b. Assuming that there is no unloading passage 197 on the auxiliary piston hole 190 in the valve bridge 400 (Fig. 1 and Fig. 2), the enlarged main valve lift curve 220v produced by the enlarged conventional exhaust boss 220 during engine braking The starting point is 225h, the end point is 225c, and its highest lift 220e is the sum of 220a and 220b. Due to the unloading passage 197, the valve lift curve of the brake exhaust valve 3001 transitions to the main valve lift curve 220m at the transition point 220t between the bottom 220a and the top 220b of the enlarged main valve lift curve 220v, and at point 220s and the main valve lift curve. The valve lift curve 220m merges and closes earlier than when there is no oil unloading channel at the end point 225b.

When the engine brake is in operation, the movement of the cam's braking bosses (exhaust gas recirculation boss 232 and compression release boss 233) is transmitted by the rocker arm 210 to the main piston 162 (Figure 1 and Figure 2), and the main piston The movement of 162 is transmitted to the auxiliary piston 160 and the exhaust valve 3001 below the auxiliary piston 160 through the hydraulic passage 412, generating brake valve liter 232v for exhaust gas recirculation and brake valve liter 233v for compression release. The brake valve lift 232v of exhaust gas recirculation starts at 225d, which is located at the later stage of the intake stroke of the engine, that is, when the valve lift curve 280v of the intake valve tends to close; the brake valve lift of exhaust gas recirculation The end point of 232v is 225e, which is located in the early stage of the compression stroke of the engine. The starting point of the compression release brake valve liter 233v is 225f, which is located at the late stage of the engine's compression stroke; the end point of the compression release brake valve liter 233v is 225g, which is located at the early stage of the engine's expansion stroke. The valve lift curve circulates between 0° and 720°, and 0° and 720° are the same point.

When the integrated exhaust boss 220 of the cam 230 rises from the inner base circle 225 (Fig. 5), the rocker arm 210 pushes the primary piston 162 (Fig. 1 and Fig. 2), the primary piston 162 pushes the secondary piston 160, and the secondary piston 160 Push the exhaust valve 3001 to move downward. When the cam 230 enters the top of the integrated exhaust boss 220 (greater than the highest lift of the brake boss 233) ( FIG. 5 ), the main piston 162 starts to drive the valve bridge 400 to move downward ( FIG. 2 ). The valve bridge 400 is separated from the brake bracket 125, the oil discharge channel 197 is opened to discharge oil, the auxiliary piston 160 moves from the extended position to the retracted position, and the valve lift curve of the brake exhaust valve 3001 changes from the transition point 220t to the main valve lift curve The 220m transition (FIG. 6) finally closes at terminus 225b, much ahead of terminus 225c without the unloading channel. This reduces the lift of the exhaust valve at the top dead center of the exhaust stroke of the engine, avoids the collision between the exhaust valve and the piston, increases the braking power, and reduces the temperature inside the cylinder.

Fig. 7 shows another cam profile of the compression release type engine braking device of the present invention. This cam profile differs from the cam profile shown in FIG. 5 by the compression release boss 233 . The first two parts of the compression release boss 233 also include an ascending section "A" and a contour section "B", but the descending section "D" after the contour section "B" does not drop to the inner base circle 225, but transitions Merges into the integrated exhaust boss 220.

Fig. 8 shows yet another cam profile of the compression release type engine braking device of the present invention. This cam profile also differs from the cam profile shown in FIG. 5 by the compression release boss 233 . The first two parts of the compression release boss 233 also include an ascending section "A" and a contour section "B", but they do not descend after the contour section "B", but pass through a slowly rising section "E" to merge into the integrated Type exhaust boss 220. The cam 230 enters the slow-rising section "E" from the contour section "B" of the brake boss, and the main piston 160 pushes the valve bridge 400 downward from the retracted position of the main piston hole bottom 446 of the valve bridge 400 (Fig. 2), The valve bridge 400 is separated from the brake bracket 125 located on the valve bridge 400, and the oil unloading channel 197 in the valve bridge 400 above the auxiliary piston hole 190 is opened to discharge oil, and the auxiliary piston 160 moves upward in the auxiliary piston hole 190 of the valve bridge 400. In the retracted position, the exhaust valve 3001 below the secondary piston 160 is closed upwards. That is to say, the unloading channel 197 on the secondary piston hole 190 in the valve bridge 400 will be opened in the slow-rising section "E", and the brake valve lift of the brake exhaust valve 3001 may drop from the highest valve lift to zero ( closure).

Example 2:

As shown in FIG. 9 and FIG. 10 , the second embodiment of the compression-release engine braking device of the present invention has the cam in the position of the inner base circle during non-braking and braking. The difference between this embodiment and the first embodiment is that this embodiment uses a different brake bracket 125 . The brake bracket 125 located above the valve bridge 400 has two main functions: one is to support the valve bridge 400 during engine braking, prevent or limit the upward movement of the valve bridge 400, and close the oil discharge channel above the auxiliary piston hole 190 197, bear the braking load transmitted from the brake exhaust valve 3001; second, in each cycle of engine braking, when the top of the integrated exhaust boss 220 pushes the valve bridge down, the secondary piston hole is opened The oil unloading channel 197 above the 190 unloads the oil, and resets the valve lift curve of the brake exhaust valve 3001. Of course, the oil unloading mechanism is also used to release the braking operation of the engine.

The brake bracket 125 in this embodiment also includes other connecting parts, such as a transition piston 161 . The transition piston 161 is slidably disposed in the transition piston hole 191 above the valve bridge 400 to form an automatic gap compensation mechanism. The oil unloading channel 197 is above the auxiliary piston hole 190, and connects the transition piston hole 191 and the auxiliary piston hole 190 (the size of the two piston holes is determined according to needs, and their sizes are not necessarily the same). An oil unloading passage 196 is added in the transition piston 161 . The range of movement of transition piston 161 is controlled by pressure plate 178 . The pressing piece 178 is fixed on the valve bridge 400 by a screw 179 . The moving range of the transition piston 161 can also be controlled by other means, such as snap rings and the like. The top of the transition piston 161 links to each other with another connector of the brake bracket 125 as the foot pad 1142 . Like foot pad 1142 is enclosed within on the pressing ball of pressing ball bar 1103. The ball bar 1103 can also be combined with the adjustment screw 1102 . There can be certain relative movement or clearance between elephant foot pad 1142 and pressure ball, and spring 177 will bias foot pad 1142 downwards on the transition piston 161, sealing oil discharge passages 196 and 197 (machine oil cannot pass through the transition piston hole 191 and secondary piston hole 190 to leak out).

When engine braking is not required, as shown in FIG. 4 , the brake control mechanism 50 is turned off, oil supply to the brake drive mechanism 100 is stopped, and the brake device is in a non-braking state as shown in FIG. 9 . The primary piston hole 415 and the secondary piston hole 190 are in an oil draining state due to the oil unloading mechanism. The main piston 162 is pressed against the retracted position of the bottom surface 446 of the main piston hole 415 under the action of the pre-tension spring 198 , forming a gap 134 between the cam follower 235 and the inner base circle 225 of the cam 230 . The auxiliary piston 160 is pressed against the retracted position of the bottom surface of the auxiliary piston hole 190, and the exhaust valve 3001 under the auxiliary piston 160 is in the closed position. The transition piston 161 of the brake bracket 125 is pressed against the retracted position of the bottom surface of the transition piston hole 191 under the action of the spring 177 . When the cam 230 entered the braking boss 232 or the braking boss 233 from the inner base circle 225, due to the gap 134 inside the exhaust valve driving chain (between the cam follower 235 and the cam 230), the braking boss 232 or Movement of detent boss 233 is skipped or lost and not transferred to exhaust valve 300 . When the cam 230 enters the top of the integrated exhaust boss 220 (Figures 5, 7 and 8), the motion of the cam is transmitted in a mechanically chained manner through the rocker arm 210, the primary piston 162, the valve bridge 400 and the secondary piston 160 To the exhaust valves 300 (the first exhaust valve 3001 and the second exhaust valve 3002), conventional exhaust valve movement is produced.

When engine braking is required, as shown in FIG. 3 , the brake control mechanism 50 is opened to supply oil to the brake drive mechanism 100 . The braking device enters the braking state shown in FIG. 10 from the non-braking state shown in FIG. 9 . The low-pressure engine oil enters the main piston hole 415 from the oil supply passage through the oil supply check valve 172 . Under the action of oil pressure, the main piston 162 moves up from the retracted position of the bottom surface 446 of the main piston hole 415 of the valve bridge 400 to the extended position, and pushes the rocker arm 210 to rotate clockwise until the cam follower 235 and the inner cam 230 until the base circle 255 touches. At this time, a brake gap 234 (corresponding to the gap 134 in FIG. 9 ) is formed between the main piston 162 and the bottom surface 446 of the main piston hole 415 (that is, the valve bridge 400), and the main piston hole 415 and the auxiliary piston hole are opened. Opening 472 of hydraulic passage 412 between 190 . Oil flow enters secondary piston bore 190 and transition piston bore 191 above it. Oil pressure overcomes the active force of spring 177, promotes transition piston 161 upwards and presses against like foot pad 1142, seals the oil unloading channel, prevents the machine oil in the transition piston hole 191 and the secondary piston hole 190 from leaking upwards. In this way, a hydraulic link is formed between the main piston 162 and the auxiliary piston 160, and the downward movement of the main piston 162 in the main piston hole 415 of the valve bridge 400 will be hydraulically transmitted to the valve through the hydraulic channel 412 The auxiliary piston 160 in the bridge 400 and the auxiliary piston hole 190 is then passed to the first exhaust valve 3001 below.

The whole process of the cam 230 opening the brake exhaust valve 3001 and the non-brake exhaust valve 3002 through the exhaust valve drive chain is basically the same as that of the first embodiment, and will not be repeated here.

The above description discloses a new compression release engine braking apparatus and method. The above-mentioned embodiments should not be regarded as limiting the scope of the present invention, but as some specific examples representing the present invention, from which many other variations are possible. For example, the compression release engine braking apparatus and method herein can be used not only for overhead cam engines, but also for pushrod engines. In addition, the one-way oil supply valve 172 can adopt different forms, such as ball valve, disc valve and so on. The one-way oil supply valve 172 can also be arranged in different positions, such as inside the main piston 162 . Since the main piston 162 in the valve bridge 400 (through the valve gap adjustment mechanism) is always close to the rocker arm 210, the one-way oil supply valve 172 can also be placed in the oil supply channel above the main piston 162, such as in the rocker arm 210 In the oil passage 214. The one-way oil supply valve 172 only allows oil to flow into the main piston hole 415 below the main piston 162 from its upstream oil supply passage in one direction.

In addition, besides the oil unloading mechanism formed by the oil unloading channel 197 above the auxiliary piston hole 190 and the brake bracket 125, other forms of oil unloading valves are also possible. The oil unloading valve of the oil unloading mechanism is in a closed state when the brake boss pushes the main piston 162 to slide relatively in the brake box. When the top of the integrated exhaust boss further pushes the main piston 162 to move, the oil unloading valve of the oil unloading mechanism opens to unload oil.

In addition, the main piston 162, the auxiliary piston 160 and the transition piston 161 can adopt different forms, such as "H" type and "T" type, etc.; the exhaust valve for braking can be the first exhaust valve 3001, or The second exhaust valve 3002.

In addition, the installation of the brake bracket 125 can also have various forms, in addition to being fixed on different parts and positions of the engine, it can also be integrated in the moving parts of the engine. For example, the brake bracket 125 of the second embodiment can be integrated on the rocker arm 210 . At this time, the secondary piston 160 is located on the second exhaust valve 3002 . Transition piston 161 also functions as a second main piston in addition to play compensation. That is to say, during braking, the elephant foot 114 on the rocker arm 210 pushes the main piston 162 , and at the same time, the elephant foot 1142 of the brake bracket 125 on the rocker arm 210 pushes the transition piston 161 . Then, the primary piston 162 and the transition piston 161 jointly push the secondary piston 160 through a hydraulic link to open the second exhaust valve 3002 . The connecting parts of the brake bracket 125 can also choose different styles, or adopt different sealing measures, such as adding seals, etc., to ensure the sealing of the oil unloading passage.

Also, the manner in which the main piston 162 blocks the inlet 472 of the hydraulic channel 412 can also be different. For example, the inlet 472 of the hydraulic channel 412 is designed below the main piston 162 (rather than on the side), and when the main piston 162 moves to the retracted position of the main piston hole bottom 446, the bottom surface of the main piston 162 covers the inlet 472.

In addition, besides using the valve bridge 400 as the brake housing, other forms are also possible. For example, the overhead brake box fixed on the engine. Accordingly, the scope of the present invention should be determined not by the specific examples above but by the appended claims.

Claims (32)

1. A compression release type engine braking method, comprising a process of utilizing the exhaust valve drive chain of the engine to open the exhaust valve, the exhaust valve drive chain comprising a cam, a rocker arm and a valve bridge, the engine The exhaust valve includes a first exhaust valve and a second exhaust valve, and the cam contains at least one brake boss, and the brake boss includes a rising from the inner base circle of the cam The ascent section to the maximum lift and the same height section to maintain the maximum lift, an oil supply channel is arranged in the rocker arm, and it is characterized in that: an upward opening is set in the center of the valve bridge The main piston hole is provided with an auxiliary piston hole opening downward at one end of the valve bridge, a hydraulic channel is connected between the main piston hole and the auxiliary piston hole, and a main piston is slidably arranged in the main piston hole. The primary piston has an extended position and a retracted position relative to the primary piston hole, and a secondary piston is slidably set in the secondary piston hole, and the upper end of the primary piston is connected with the rocker arm, and a secondary piston is set in the primary piston. The oil passage communicates the upper end of the oil passage with the oil supply passage in the rocker arm, and communicates the lower end of the oil passage with the main piston hole, between the main piston hole and the oil supply passage, or between the oil supply passage A one-way oil supply valve is arranged in the passage, and the oil supply direction of the one-way oil supply valve is from the oil supply passage to the main piston hole, and the lower end of the auxiliary piston is connected with the first exhaust valve, and the The lower side of the other end of the valve bridge is connected with the second exhaust valve, and a brake bracket is arranged on the upper side of the valve bridge where the auxiliary piston hole is located, and the exhaust valve drive chain of the engine is used to open the exhaust valve. In the process of the valve, firstly, oil is supplied to the main piston hole through the oil supply passage and the one-way oil supply valve, the main piston is placed in the extended position, and the hydraulic passage between the main piston hole and the auxiliary piston hole is opened , and then, use the rising section of the brake boss in the cam to drive the rocker arm, so that the rocker arm pushes the main piston to move from the extended position to the retracted position, and at the same time, the brake bracket is used to prevent the valve bridge from moving upward, Use the hydraulic pressure in the hydraulic channel to transmit the movement of the main piston to the auxiliary piston, forcing the auxiliary piston to protrude downward in the auxiliary piston hole, open the first exhaust valve, and then use the brake boss in the cam The contour section drives the rocker arm, keeps the main piston in the retracted position in the main piston hole, blocks the hydraulic transmission between the main piston hole and the auxiliary piston hole through the hydraulic channel, and keeps the auxiliary piston in the auxiliary piston hole. The protruding position in the piston hole keeps the first exhaust valve open, and at the same time, the brake bracket is used to bear the brake load on the auxiliary piston. 2. The compression release engine braking method according to claim 1, characterized in that: at least one oil unloading passage is arranged in one end of the valve bridge where the auxiliary piston hole is located, and the lower end of the oil unloading passage is connected to the auxiliary piston. The holes communicate with each other, and the upper end opening of the oil unloading channel is closed by the lower end of the brake bracket. 3. The compression release engine braking method according to claim 1, characterized in that: a descending section is set on the braking boss, and the starting point of the descending section is connected to the contour end of the segment, drop the end of the segment back to or close to the inner base circle of the cam. 4. The compression-releasing engine braking method according to claim 3, characterized in that: when the braking boss in the cam passes through the contour section and enters the descending section, the rocker arm is used to perform reverse movement, so that The main piston moves from the retracted position to the extended position, opens the opening of the hydraulic channel on the main piston hole, and connects the hydraulic transmission between the main piston hole and the auxiliary piston hole, so that the force of the auxiliary piston on the first exhaust valve Move down to the retracted position. 5. The compression release engine braking method according to claim 1, characterized in that: the oil passage in the main piston is arranged along the axial direction of the main piston, and the lower end opening of the oil passage is arranged in the lower end surface of the main piston . 6. The compression release engine braking method according to claim 2, characterized in that: an integrated exhaust boss is set on the cam, and a slow-rising section is set on the brake boss, Connect the starting point of the slow-rising section to the end of the contour section, connect the end point of the slow-rising section to the integrated exhaust boss, and brake the boss in the cam after passing the contour section , In the process of entering the slow-rising section, use the slow-rising section of the brake boss to drive the rocker arm, so that the rocker arm pushes down the valve bridge through the main piston located in the retracted position in the main piston hole, so that the auxiliary piston One end of the valve bridge where the hole is located is separated from the above-mentioned brake bracket on the upper side, and the upper end opening of the oil discharge channel is opened to discharge oil, reducing the hydraulic pressure in the hole of the auxiliary piston, so that the force of the auxiliary piston on the first exhaust valve Moving up in the secondary piston bore to the retracted position causes the first exhaust valve to move up to the closed position. 7. The compression release engine braking method according to claim 1, wherein the process of using the exhaust valve driving chain of the engine to open the exhaust valve comprises the following steps: 1) Open the brake control mechanism of the engine, supply oil to the main piston hole in the valve bridge through the oil supply channel and the one-way oil supply valve, 2) The main piston is placed in the extended position in the main piston hole, and the hydraulic passage between the main piston hole and the auxiliary piston hole in the valve bridge is opened, 3) The auxiliary piston is in the retracted position in the auxiliary piston hole, and the first exhaust valve under the auxiliary piston is in the closed position, 4) The braking boss of the cam moves upward from the inner base circle, driving the main piston in the main piston hole to move down to the retracted position in the main piston hole of the valve bridge, 5) The brake bracket on the valve bridge above the auxiliary piston hole prevents or restricts the upward movement of the valve bridge, 6) The downward movement of the main piston is transmitted to the auxiliary piston through the hydraulic channel, and the auxiliary piston in the auxiliary piston hole of the valve bridge moves downward to the extended position to open the first exhaust valve, 7) The brake boss of the cam reaches the highest lift and continues to maintain the highest lift position, 8) The main piston reaches the retracted position downward in the main piston hole of the valve bridge, closing the hydraulic channel between the main piston hole and the auxiliary piston hole, preventing the hydraulic load on the auxiliary piston from being transmitted to the main piston, 9) The auxiliary piston reaches the extension position downward in the auxiliary piston hole of the valve bridge, and keeps the first exhaust valve under the auxiliary piston open at the highest brake valve lift position, 10) Use the brake bracket on the upper side of the valve bridge where the auxiliary piston hole is located to support the load transmitted from the first exhaust valve to the auxiliary piston, 11) The braking boss of the cam descends from the highest lift back to the inner base circle, 12) The main piston moves upward from the retracted position in the main piston hole of the valve bridge back to the extended position, opening the hydraulic channel between the main piston hole and the auxiliary piston hole, 13) The auxiliary piston moves upward from the extended position in the auxiliary piston hole to the retracted position, 14) The first exhaust valve moves upward from the highest brake valve lift position to the closed position. 8. The compression release engine braking method according to claim 2, characterized in that: the process of using the exhaust valve driving chain of the engine to open the exhaust valve further comprises the following steps: 1) Turn off the brake control mechanism of the engine, stop supplying oil to the main piston hole in the valve bridge, 2) The cam drives the main piston in the main piston hole of the valve bridge to move downward, 3) The main piston drives the valve bridge to move downward, and the end of the valve bridge where the auxiliary piston hole is located is separated from the brake bracket on the upper side. 4) Open the oil unloading channel above the auxiliary piston hole to unload oil, 5) The auxiliary piston moves from the auxiliary piston hole of the valve bridge to the retracted position. 9. The compression release engine braking method according to claim 1, characterized in that: when the main piston slides from the retracted position to the extended position in the main piston hole, the main piston is used to open the hydraulic passage located in the main piston hole When the main piston slides from the extended position to the retracted position in the main piston hole, the main piston closes the opening of the hydraulic passage located on the main piston hole. 10. The compression release engine braking method according to claim 2, characterized in that: the oil discharge channel is provided with an outlet, and when the valve bridge moves downwards driven by the cam, the valve bridge is separated from the brake bracket , open the outlet of the oil unloading channel. 11. The compression release engine braking method according to claim 1, characterized in that: the brake bracket is fixed on the engine, the brake bracket includes a connecting piece, and the connecting piece is located on the valve above the bridge. 12. The compression release engine braking method according to claim 1, characterized in that: the brake bracket is integrated on the rocker arm, the brake bracket includes a connecting piece, and the The connection piece is located above the valve bridge. 13. The compression-releasing engine braking method according to claim 1, wherein said braking boss includes a compression-releasing boss, and said compression-releasing boss is located at a later stage of the compression stroke of the engine. It rises from the inner base circle of the cam, reaches the highest position near the compression top dead center of the engine, and descends back to the inner base circle of the cam in the early stage of the expansion stroke of the engine. 14. The compression release engine braking method according to claim 1, characterized in that: said braking boss includes a compression release boss and an exhaust gas recirculation boss, said compression release boss The platform starts to rise from the inner base circle of the cam at the later stage of the compression stroke of the engine, and reaches the highest position near the compression top dead center of the engine, and descends back to the inner base circle of the cam at the early stage of the expansion stroke of the engine. The air recirculation boss rises from the inner base circle of the cam at the end of the intake stroke of the engine and descends back to the inner base circle of the cam at the beginning of the compression stroke of the engine. 15. The compression-releasing engine braking method according to claim 1, wherein an integrated exhaust boss is provided on the cam, and the braking boss includes a compression-releasing boss , the compression release boss starts to rise from the inner base circle of the cam at the later stage of the compression stroke of the engine, and rises to the highest position before the top dead center of the compression stroke of the engine, during the remainder of the compression stroke of the engine and the The initial expansion stroke maintains said uppermost position, and during the remainder of the engine's expansion stroke descends back to the inner base circle of the cam or merges into the integrated exhaust boss, which consists of bottom and top Composition, the bottom of the integrated exhaust boss is close to the same height as the brake boss, and the top of the integrated exhaust boss is close to the same height as the regular boss of the engine. 16. The compression release engine braking method according to claim 1, characterized in that: said brake boss includes an exhaust gas recirculation boss, said exhaust gas recirculation boss is located on the engine It rises from the inner base circle of the cam in the latter part of the intake stroke and descends back to the inner base circle of the cam in the early part of the compression stroke of the engine. 17. The compression release engine braking method according to claim 1, wherein an integrated exhaust boss is provided on the cam, and the brake boss includes a compression release boss , the compression release boss starts to rise from the inner base circle of the cam in the second half of the compression stroke of the engine, and rises to the highest position before the compression top dead center of the engine, during the rest of the compression stroke of the engine and the The uppermost position as described is maintained early in the expansion stroke, rising into the integrated exhaust boss during the remainder of the engine's expansion stroke. 18. The compression release type engine braking method according to claim 1, wherein a preloaded spring is used to maintain the exhaust valve generated by the retracted position and extended position of the main piston inside the exhaust valve drive chain. Drive chain brake gap, using the exhaust valve drive chain brake gap to eliminate non-following and impact inside the exhaust valve drive chain. 19. A compression release engine brake device, comprising a brake control mechanism and a brake drive mechanism, characterized in that: the brake control mechanism includes a control valve connected with a hydraulic pressure generating device, and the brake drive mechanism It includes a brake box, an oil supply mechanism, an oil unloading mechanism and a brake cam. The brake box is provided with a main piston hole and an auxiliary piston hole, and a line is arranged between the main piston hole and the auxiliary piston hole. The connected hydraulic channel, the main piston is slidably arranged in the main piston hole, and the auxiliary piston is slidably arranged in the auxiliary piston hole. The oil supply mechanism includes an oil supply channel and a one-way oil supply valve. The control valve in the dynamic control mechanism is connected to the inlet of the oil supply passage, the outlet of the oil supply passage is connected to the main piston hole, and the one-way oil supply valve is arranged on the oil supply passage or the oil supply passage and the main piston hole. Between, the oil supply direction of the one-way oil supply valve is from the oil supply passage into the main piston hole, the oil unloading mechanism includes an oil unloading valve, the oil unloading valve communicates with the secondary piston hole, and the control The moving cam contains at least one braking boss. 20. The compression-release engine braking device according to claim 19, wherein the brake box is formed by a valve bridge, and the main piston hole is arranged at the center of the valve bridge upwards. In the opening, the auxiliary piston hole is set in a downward opening at one end of the valve bridge, the hydraulic passage is set in the valve bridge and communicates with the main piston hole and the auxiliary piston hole, and the main piston is set in the main piston hole. In the piston hole, the auxiliary piston is arranged in the auxiliary piston hole, and the upper end of the main piston is connected with the rocker arm of the engine. An oil supply channel is arranged in the rocker arm, and an oil passage is arranged in the main piston. The upper end of the oil passage communicates with the oil supply passage in the rocker arm, the lower end of the oil passage communicates with the main piston hole, and the one-way oil supply valve is arranged between the main piston hole and the oil supply passage or the supply In the oil passage, the oil supply direction of the one-way oil supply valve is from the oil supply passage to the main piston hole. A brake bracket is arranged on the upper side of the valve bridge where the auxiliary piston hole is located. One end of the valve bridge is provided with at least one oil unloading channel, one end of the oil unloading channel communicates with the auxiliary piston hole, the other end of the oil unloading channel is closed by the lower end of the brake bracket, and the brake cam is provided with an integrated Exhaust boss. 21. The compression-release engine brake device according to claim 20, wherein the lower end of the auxiliary piston is connected with a first exhaust valve of the engine exhaust valve, and the lower side of the other end of the valve bridge is connected with the exhaust valve of the engine. A second exhaust valve in the door is connected. 22. The compression release engine brake device according to claim 20, wherein the brake bracket is fixed on the engine, and the brake bracket includes a connecting piece, and the connecting piece is located on the valve bridge above. 23. The compression release engine braking device according to claim 20, wherein the brake bracket is integrated on the rocker arm, and the brake bracket includes a connecting piece, and the connecting piece is located at the valve above the bridge. 24. A compression-release engine braking device as claimed in claims 22 and 23, characterized in that the connecting part of the brake bracket comprises a transition piston, and the transition piston is slidably arranged on the transition of the valve bridge. In the piston hole, the transition piston hole is located above the auxiliary piston hole. 25. The compression release engine braking device of claim 20, wherein said brake boss includes a compression release boss, and said compression release boss is located at a later stage of the compression stroke of the engine. It rises from the inner base circle of the cam, reaches the highest position near the compression top dead center of the engine, and descends back to or close to the inner base circle of the cam in the early stage of the expansion stroke of the engine. 26. The compression-release engine braking device according to claim 20, wherein said brake boss includes a compression release boss and an exhaust gas recirculation boss, said compression release boss The table rises from the inner base circle of the cam at the end of the engine's compression stroke, and reaches the highest position near the compression top dead center of the engine, and descends back to or close to the inner base circle of the cam at the beginning of the engine's expansion stroke, said The EGR boss starts rising from the inner base circle of the cam late in the engine's intake stroke and descends back to the inner base circle of the cam early in the engine's compression stroke. 27. The compression release engine braking device according to claim 20, wherein an integrated exhaust boss is provided on said cam, and said brake boss includes a compression release boss The compression release boss starts to rise from the inner base circle of the cam at the end of the engine's compression stroke, and rises to the highest position before the engine's compression stroke top dead center, during the remainder of the engine's compression stroke and the engine The initial expansion stroke of the engine maintains the uppermost position, and during the remainder of the expansion stroke of the engine drops back to the inner base circle of the cam or merges into the integrated exhaust boss, which is composed of the bottom and Composed of the top, the bottom of the integrated exhaust boss is close to the same height as the brake boss, and the top of the integrated exhaust boss is nearly the same as the regular boss of the engine. 28. The compression-release engine brake device according to claim 20, wherein said brake boss includes an exhaust gas recirculation boss, said exhaust gas recirculation boss is located on the engine It rises from the inner base circle of the cam in the latter part of the intake stroke and descends back to the inner base circle of the cam in the early part of the compression stroke of the engine. 29. The compression release engine brake device according to claim 20, wherein an integrated exhaust boss is provided on said cam, and said brake boss includes a compression release boss The compression release boss starts to rise from the inner base circle of the cam in the second half of the engine's compression stroke, and rises to the highest position before the engine's compression top dead center, during the rest of the engine's compression stroke and the engine The uppermost position is maintained early in the expansion stroke, rising into the integrated exhaust boss during the remainder of the engine's expansion stroke. 30. The compression release engine brake device according to claim 20, characterized in that a pre-tension spring is arranged in the brake driving mechanism. 31. The compression release engine brake device according to claim 30, wherein one end of the pre-tension spring is placed on the engine, and the other end of the pre-tension spring acts on the rocker arm on one end. 32. The compression-release engine brake device according to claim 20, characterized in that an automatic backlash compensation mechanism is set in the brake drive mechanism.

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