JPS6114981B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluid pressure brake system for a vehicle, and more particularly to a reservoir, an emergency brake maintained in a released state by a release pressure communicating from the reservoir, and a release pressure connected to the emergency brake. a supply line communicating with the reservoir, a service brake, a service line, and a service brake application control responsive to a fluid pressure level in the service line communicating the service brake with a fluid pressure level in the reservoir. The present invention relates to a brake device including the following.

In some countries, regulations require that automobiles equipped with air brake systems must stop within a certain distance in the event of an emergency, such as when a failure occurs in the brake system. To date, this emergency braking is generally performed by a spring brake drive as an emergency brake, which is normally kept in a released state by a fluid release pressure. When the emergency release pressure is discharged, the spring brake drive applies the vehicle's brakes to stop the vehicle. Similarly, spring brake drives are also used when the vehicle is parked. However, the use of spring brake systems in emergency situations has many drawbacks, so it is desirable to use spring brake drives only for parking purposes. Furthermore, in order to obtain the fairly high braking torque needed to stop the vehicle in an emergency, it is necessary to use spring brake drives on all wheels of the vehicle, increasing the cost of the air brake system. .

An object of the present invention is to apply the service brake by using the release pressure used to keep the emergency brake in the released state during an emergency or parking, so that the emergency brake is used only to maintain the parked state. It is an object of the present invention to provide a fluid pressure brake system for a vehicle that is particularly suitable for use as a brake system for a trailer.

To achieve this objective, a brake system of the above-described type according to the invention is responsive to fluid pressure levels in a supply line and communicates the supply line with a reservoir and an emergency brake, and between a reservoir and a service brake application control system. an emergency brake system including a piston movable from a first position in which communication is prevented between the reservoir, the supply line, and the emergency brake to a second position in which communication is initiated between the emergency brake and the service brake application control; apparatus is provided, and when the fluid pressure level decreases to a predetermined level, the piston moves to the second position to communicate release pressure to a brake application control, which communicates service brake to the reservoir. The system is characterized in that the brake is applied for regular use.

According to the above arrangement, in an emergency or when the vehicle is parked, the fluid pressure level in the trailer supply line drops to a relatively low level and the emergency device releases release pressure from the reservoir to the emergency brake or spring brake drive. The communication is interrupted and the release pressure that was communicated to the spring brake drive can be used to cause service brake application to occur independent of the fluid pressure level in the trailer's service line. Therefore, even in an emergency, sufficient brake torque can be obtained to stop the trailer by applying the service brake, and since the spring brake drive is used only for parking, four wheels are mounted. Only two spring brake drives are required for trailers with tandem axles, which saves the cost of providing spring brake drives on the other wheels of the tandem axle unit and considerably reduces the cost of trailer brakes. can be reduced.

In a preferred embodiment, a pressure responsive device is provided for preventing communication between the service line and the service brake application control device when the piston is in the second position and the release pressure is in communication with the service brake application control device. It is provided. This prevents the service brake from being damaged if normal service drive is attempted while the service brake is already applied by release pressure. Additionally, an orifice is provided to reduce this release pressure at a predetermined rate. Therefore, emergency applications are made by using the service brakes of the vehicle and parking drive is only applied by the spring brake drive after the release pressure has been exhausted to a predetermined low level required to drive the spring brake drive. It will be done.

These and other features and advantages of the invention will become apparent from the following description of a preferred embodiment, taken in conjunction with the accompanying drawings.

The emergency valve, indicated generally at 10 in the drawings, includes a housing 12 having an inlet 14 connected to a trailer supply line 16 and another inlet 18 connected to a trailer service line 20. During normal operating conditions, fluid pressure within trailer supply line 16 is maintained at a substantially constant level by an air compressor (not shown) driven by the vehicle's engine. However, in the event of a failure of the fluid pressure brake system, the supply line 16 is vented to a relatively low pressure level by a conventional tractor protection valve (not shown) supported by the tractor of the tractor and trailer combination. Trailer regular use line 20
Although normally at a low pressure level, fluid pressure is communicated through the trailer service line 20 when brake application is effected by actuation of a conventional brake valve (not shown) mounted in the cab of the tractor. to operate the regular brake.

Valve 10 includes outlets 22 and 24 that communicate with service reservoirs 26 and 8, respectively. Further outlets 30 of valve 10 communicate with conventional spring brake drive release ports 32 and 34, indicated generally at 36 and 38. Spring brake drive 36 and 3
8 is of conventional type and may be constructed according to any construction known to those skilled in the art. A common spring brake drive of the type schematically shown in the drawings includes a spring chamber in which a relatively strong spring is kept in an unactuated state by fluid pressure in communication with release ports 32 and 34. drooping Spring brake drives 36 and 38 also include service brake chambers that are driven to effect service brake application by communicating fluid pressure through service ports 40 and 42. The spring brake drives 36 and 38 are of conventional construction and will not be described in further detail.

Fluid pressure communication to service ports 40 and 42 is controlled by relay valves designated generally at 44 and 46. These relay valves are of conventional construction and will not be described in further detail. Ports 48 and 50 of relay valves 44 and 46 communicate with outlet 53 of emergency valve 10.

Housing 12 has an aperture defined therein, indicated generally at 52. The hole 52 has a large diameter portion 54, a small diameter portion 56, a portion 58 having approximately the same diameter as the portion 54, and a portion 6 having a larger diameter.
0 and a maximum portion 62. Correspondingly stepped piston 64
is slidably fitted within bore 52 and defines a fluid pressure responsive surface 66 exposed to the fluid pressure level within inlet 14 . Spring 68 urges piston 64 toward the position shown. Piston 64 supports seals 70 and 72 which sealingly engage portion 56 of bore 52 depending on the position of the piston. piston 64
Also supports seals 74, 76 and 78 which sealingly engage portions 58, 60 and 62 of bore 52, respectively. The largest portion 62 of the bore 52 communicates with service reservoirs 26 and 28 via passageways 80 and 82 which communicate with outlets 22 and 24, respectively. Check valves 84 and 86 are provided in passages 80 and 82, respectively, to permit unrestricted fluid communication to common reservoirs 26 and 28, but prevent reverse communication. A pressure differential shuttle 88 is provided within a passageway 90 that communicates outlet 22 with outlet 24 and communicates the higher fluid pressure level of outlets 22 and 24 with passageway 92. Passage 92 communicates with portion 58 of stepped hole 52 . Exit 30 is passage 94
communicates with portion 56 of hole 52 by. A differential pressure sensitive shuttle 96, which is identical to the shuttle 88, is connected to the inlets 18 and 52.
The higher fluid pressure level of the portion 54 is connected to the outlet 53.
communicate with. A flow restriction orifice 98 communicates portion 54 of bore 52 with the surrounding atmosphere. A further passageway 100 communicates the inlet 18 with the inlet 14. Passage 1
A check valve 102 in 00 allows communication from inlet 18 to inlet 14, but prevents communication in the opposite direction. Passageway 100 also includes a flow restriction orifice 104 that limits fluid communication through passageway 100 to a predetermined rate.

A number of the components of the emergency valve 10 are shown in the drawing in the position when the air brake system is fully vented. When a vehicle is operated, the vehicle's engine is started and operates a conventional air compressor. Operation of the air compressor causes fluid pressure to act through the trailer supply line 16 against the face 66 of the piston 64, forcing it upwardly in the drawing against the force exerted by the spring 68. As a result, the seal 70 sealingly engages the portion 56 of the hole 52 and blocks communication between the outlet 30 and the portion 54 of the hole 52 via the passageway 94. At the same time, it is separated from portion 56 of seal 72 and pushed into large diameter portion 58 . At the same time, the seal 76 is pushed into the largest diameter portion 62 of the bore 52 to initiate substantially unrestricted fluid communication between the supply line 16 and the passageway 80. Fluid pressure within passageway 80 also communicates with passageway 82 and reservoir 26 .
Since the pressure levels in passages 80 and 28 are at relatively low levels, the high fluid pressure level in passages 80 and 82 opens check valves 84 and 86, communicating fluid pressure through outlets 22 and 24 to normal storage. Fill vessels 26 and 28. At the same time, the seal 72 closes the large diameter portion 58 of the hole.
Being pushed inward allows substantially unrestricted fluid communication between passageways 92 and 94. Accordingly, the relatively high fluid pressure level communicating with reservoirs 26 and 28 also communicates via outlet 30 to release ports 32 and 34 of spring brake drives 36 and 38. The release pressure compresses the springs contained within drives 36 and 38 to release the vehicle's parking brake.
The vehicle can now be moved.

If service brake application is accomplished by actuation of a conventional driver-controlled valve mounted within the cab of the vehicle, fluid pressure is communicated through service line 20 and inlet 18. Since portion 54 of bore 52 is at approximately atmospheric pressure due to fluid communication through orifice 98, the relatively high fluid pressure level at inlet 18 forces shuttle 96 into the position shown to force inlet 1
8 and outlet 53 allowing substantially unrestricted fluid communication. This fluid pressure level at outlet 53 communicates with service ports 48 and 50 of relay valves 44 and 46. Relay valves 44 and 46 transfer fluid pressure stored in reservoirs 28 and 26 to spring brake actuator 36 in response to fluid pressure levels at service ports 48 and 50, respectively.
and 38 begin to communicate with common ports 40 and 42. Relay valves 44 and 46 therefore provide service brake application in the normal manner. When the operator-controlled valve is released, the fluid pressure level at inlet 18 is reduced to a relatively low level allowing relay valves 44 and 46 to vent fluid pressure in communication with service ports 40 and 42.

In emergency conditions, such as when a failure prevents normal operation of the vehicle air brake system, the trailer supply line 16 is vented by a conventional tractor protection valve supported on the vehicle. Supply line 16
When vented, the pressure in inlet 14 is reduced to a relatively low level forcing spring 68 to force piston 64 into the position shown. As a result, seal 76 sealingly engages portion 60 of bore 52 to block communication from supply line 16 to service reservoirs 26 and 28. However, the fluid in the reservoir is
is retained in the reservoir. At the same time, the sealed body 7
2 is sealingly engaged with portion 56 of bore 52 to interrupt fluid communication between passageway 92 and passageway 94.
Although sealingly engaged with portion 56 of seal 72, seal 70 is spaced from portion 56 and pushed into larger diameter portion 54 to initiate communication between passageway 94 and portion 54 of bore 52. Portion 54 of bore 52 also communicates with outlet 53 via shuttle 96, as described above. Because the pressure level at inlet 18 when no service brake application is occurring is relatively low, substantially unrestricted fluid communication is permitted through outlet 53. Therefore, the release pressure at ports 32 and 34 releasing the spring brake drive is applied to passage 9.
4. Directly communicates with the common ports 48 and 50 in the hole 52 portion. This release pressure operates relay valves 44 and 46 in a normal manner to provide service brake emergency activation. Of course, the fluid pressure level within section 54 is evacuated via orifice 98 at a predetermined rate. As a result, after a predetermined period of time, the release pressure in the ports 32 and 34 is completely exhausted, allowing the spring brake drive to drive the brakes. However, because the orifice 98 is sized to allow relatively limited fluid flow, the vehicle may be brought to a stop using the service brakes. The spring brake drive is then used only for parking purposes. Of course, when the trailer is parked, the operator operates a conventional push-pull valve in the cab to vent the trailer supply line 16. Venting of this supply line 16 when the trailer is parked causes the valve 10 to be actuated to activate the service brake in the same manner as described above in the parking emergency actuation. Once the release pressure has been discharged to a fairly low level after the trailer has been parked, the spring brake drive will of course act in a normal manner to keep the vehicle restrained.

Of course, if normal service drive is attempted while the service brake is applied by the release pressure, the service brake will not be able to withstand the double drive pressure and may fail. As a result, if a service brake application is to be performed after an emergency application has been made, a relatively high pressure level communicating with the inlet 18 will pass through the check valve 102 to the passage 1.
00 to the relatively low pressure of the supply line 16. During normal operation of the vehicle, supply line 16 is always maintained at a relatively high fluid pressure level;
It is only vented during emergencies or parking. As a result, check valve 102 remains closed during normal operation of the vehicle. However, during an emergency or parking situation, the pressure communicated to the inlet 18 by the service brake drive is communicated through the check valve 102 to a relatively low pressure level in the supply line 16 to prevent damage to the service brake drive. . A flow restriction orifice 104 is provided to limit the rate of fluid communication through the passageway 100 so that the trailer supply line 16
is maintained at a relatively low pressure level.

[Brief explanation of the drawing]

The drawing is a schematic diagram of a brake system for a trailer equipped with an emergency valve constructed in accordance with the principles of the present invention, and shows the emergency valve in cross section. In the drawing, reference numeral 10 is an emergency valve, 12 is a housing, 14 and 18 are inlets, 16 is a supply line,
20 is a common use line 22, 24, 30, 53 is an outlet, 26, 28 is a common reservoir, 32, 34 is a release port, 36, 38 is a spring brake drive device, 44,
46 is a relay valve, 52 is a hole, 64 is a piston, 6
6 is a fluid pressure responsive surface; 84, 86, 102 are check valves; 88, 96 are pressure differential responsive shuttles; 98;
104 indicates a flow restriction orifice.

Claims (1)

[Scope of Claims] 1. A reservoir, an emergency brake maintained in a released state by a release pressure communicating from the reservoir, a supply line communicating the release pressure to the emergency brake and the reservoir, In an apparatus comprising a brake, a service line, and a service brake application control responsive to a fluid pressure level in the service line and communicating the service brake to a fluid pressure level in the reservoir, the supply line 16 a fluid pressure level within the reservoir for communicating the supply lines with the reservoirs 26, 28 and the emergency brakes 32, 34 and blocking communication between the reservoirs and the emergency brake application controllers 44, 46. a piston 64 movable from one position to a second position for blocking communication between the reservoir, the supply line and the emergency brake and initiating communication between the emergency brake and the service brake application controller;
an emergency system 10 comprising: when the fluid pressure level decreases to a predetermined level, the piston moves to the second position to communicate the release pressure to the brake application controllers 44, 46; A fluid pressure brake system for a vehicle, characterized in that application of the service brake is performed by communicating the service brake with the reservoir. 2. The fluid pressure brake device for a vehicle according to claim 1, wherein the piston 64 is pressed toward the second position by an elastic device 68. 3. A pressure responsive device 96 for blocking communication between the service line and the service brake application control device when the piston is in the second position and the release pressure is in communication with the service brake application control device.
3. A fluid pressure brake device for a vehicle according to claim 2, further comprising: 4. The vehicle according to claim 3, further comprising a device 102 for discharging the fluid pressure communicated through the service line when the release pressure is communicated with the service brake application control device. Fluid pressure brake device for use. 5. The brake system according to claim 3 or 4, further comprising a flow rate limiting orifice 98 for discharging the release pressure at a predetermined rate after the release pressure is communicated with the service brake application control device. Fluid pressure brake equipment for vehicles.