JP3796793B2 - Timer device for fuel injection pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection pump mainly used in a diesel engine, and more particularly, a timer attached to a distribution type fuel injection pump for freely adjusting the fuel injection timing in response to a command from an electronic control device. It relates to the device.
[0002]
[Prior art]
For example, as described in Japanese Utility Model Publication No. 63-110640, in a distributed fuel injection pump for a diesel engine, in order to control the fuel injection timing, timing of a cam that drives a plunger that pumps fuel is used. A timer piston is provided to change the. The timer piston can be moved by adjusting the oil pressure acting on the chambers by means such as a hydraulic control valve provided between the chambers on both sides of the timer piston, and the fuel injection timing can be adjusted. It is like that.
[0003]
A hydraulic control valve that is electromagnetically opened and closed by a solenoid coil is described, for example, in Japanese Utility Model Laid-Open No. 56-173736. By controlling the energization or shut-off of the solenoid coil in the solenoid valve as such a fuel oil pressure control valve by using an electronic control device, the oil pressure acting between the chambers on both sides of the timer piston is changed to change the timer piston. If the position is adjusted, the fuel injection timing can be controlled.
[0004]
As an example, FIG. 6 shows a conventional face cam type fuel injection pump. By controlling the oil pressure in the timer high pressure chamber 22 by the oil pressure control valve 27, the position of the timer piston 21 is moved left and right in FIG. 6 to control the injection timing.
[0005]
[Problems to be solved by the invention]
6, when a plunger (not shown) is pumped, the torque reaction force of the face cam is transmitted to the timer piston 21 via the slide pin 19 and the spherical bearing 33, and the timer piston 21 receives a force in the right direction in FIG. Therefore, the timer piston 21 vibrates every time the pressure is fed. For this reason, in the conventional timer device, the timer piston 21 collides with the timer low pressure chamber side cover 34 at the most advanced angle (when the timer piston 21 is left most in FIG. 6) due to the vibration of the timer piston 21. At the most retarded angle (when the timer piston 21 is rightmost in FIG. 6), it collides with the timer high pressure chamber side cover 35, and the impact is emitted as a sound, which is about 2 dB higher than normal. There's a problem.
[0006]
An object of the present invention is to provide a timer device of a fuel injection pump in which a timer piston does not collide with a timer low pressure chamber side cover or a timer high pressure chamber side cover when the timer device is in operation at the most advanced angle or the most retarded angle. And
[0007]
[Means for Solving the Problems]
According to the present invention, the operation range of the timer piston is limited by the hydraulic pressure, and the timer piston collides with the timer low pressure chamber side cover or the timer high pressure chamber cover at the most advanced angle or most retarded angle. Noise is reduced.
[0008]
In the present invention also by as claim 1, the first groove is cut off from the hydraulic pressure control valve by a timer piston, the pressure in the timer high-pressure chamber rises, more timer piston timer high-pressure chamber side cover direction Does not move. Therefore, the timer piston does not collide with the timer high pressure chamber side cover at the most retarded angle, and the noise is reduced.
In the present invention also by such claims 2, during most advanced, by a second groove and the third groove communicates, since the timer high-pressure chamber and the timer low-pressure chamber is communicated, The fuel in the timer high pressure chamber flows into the timer low pressure chamber, the pressure in the timer high pressure chamber decreases, and the timer piston no longer moves toward the timer low pressure chamber side cover. Therefore, the timer piston does not collide with the timer low pressure chamber side cover at the most advanced angle, and the noise is reduced.
[0009]
In the present invention also by such claims 3, by the movement of the timer piston during most retarded and a fourth groove and the timer low-pressure chamber is communicated with the fuel in the timer low-pressure chamber flows out to the low pressure side Therefore, the timer piston does not move further in the direction of the timer high pressure chamber side cover, and the timer piston does not collide with the timer high pressure chamber side cover at the most retarded angle, and noise is reduced.
[0010]
In the present invention also by such claims 4, during most advanced, since by a fifth groove and grooves 6 are communicated, where the fuel chamber and the timer low-pressure chamber communicating with the fuel The fuel in the chamber flows into the timer low pressure chamber, the pressure in the timer low pressure chamber rises, and the timer piston does not move further toward the timer low pressure chamber side cover. Therefore, the timer piston does not collide with the timer low pressure chamber side cover at the most advanced angle, and the noise is reduced.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
1 to 4 show a first embodiment of a timer device for a fuel injection pump according to the present invention. FIG. 1 is a sectional view showing the overall configuration of a face cam type fuel injection pump, and FIG. FIG. 3 and FIG. 4 are sectional views showing specific operating states of the timer device.
[0012]
First, the structure of the face cam type distributed fuel injection pump 1 shown in FIG. 1 will be described. The drive shaft 2 is rotationally driven by an engine (not shown) in synchronism with a half of the rotation of the engine. A signal rotor 3 is coaxially attached to the drive shaft 2, and a plurality of convex teeth are formed on the outer periphery thereof. A rotation angle sensor 4 faces the outer periphery of the signal rotor 3, generates a pulse signal corresponding to the engine speed by electromagnetic induction of the convex teeth of the signal rotor 3, and outputs the pulse signal to the electronic control device 5. To do. Here, the electronic control device includes a drive circuit for driving the spill valve 18 and the hydraulic control valve 27. A face cam 7 that drives a plunger 6 that pumps fuel and a vane pump 8 that is a fuel feed pump are connected to the drive shaft 2. The face cam 7 is pressed together with the plunger 6 by a spring 9 against a roller 11 provided on the roller ring 10.
[0013]
Accordingly, when the face cam 7 is rotationally driven by the drive shaft 2, the convex portion of the face cam 7 rides on the roller 11, and the face cam 7 itself and the plunger 6 integrated with the face cam 7 itself are rotated with the plunger 6. It will reciprocate in the axial direction. Since the plunger 6 is inserted into the cylinder bore 12a of the pump cylinder 12 and forms the pressure chamber 13 at the tip thereof, the volume of the pressure chamber 13 is expanded and contracted by the reciprocating component of the plunger 6, and at the same time the rotational motion of the plunger 6 is increased. Depending on the component, the suction chamber and the discharge port that open to the pressure chamber 13 are switched to communicate with each other. The fuel discharged from the discharge port of the feed pump 8 and pressurized to about 10 atm is stored in the fuel chamber 15, but the fuel is sucked into the pressure chamber 13, pressurized to a high pressure and fueled at a predetermined timing. It is pumped to the injection valve 16 and injected into a fuel chamber of an engine (not shown). The dishead 14 of the fuel injection pump 1 is provided with a spill valve 18 for releasing the pressure in the pressure chamber 13. By opening the spill valve 18 with the electronic control device 5, the fuel injection start timing and the injection amount The injection rate can be controlled.
[0014]
The cylindrical outer peripheral surface 10a of the roller ring 10 can rotate within a predetermined angle range about the axis of the drive shaft 2. Since the rotation of the roller 11 moves in the rotational direction, the timing at which the convex portion of the face cam 7 rides on the roller 11 is changed, whereby the fuel injection timing can be changed. In order to rotate the roller ring 10, a slide pin 19 extends from the roller ring 10 downward in FIG. 1, and its lower end moves up and down with respect to the paper surface in FIG. 1 in a timer cylinder 20 formed in the housing. The timer piston 21 is engaged so as to be able to reciprocate in the direction.
[0015]
FIG. 2 shows a configuration of a main part of the timer device 28 according to the first embodiment of the present invention. This first embodiment is applied to a timer device of a timer high pressure chamber control system. The timer high pressure chamber 22 on the right side of the timer piston 21 communicates with a connection hole 39 communicating with the fuel chamber 15 via a flow path 17 having a throttle 23, and receives fuel pressurized by the feed pump 8. The oil pressure pushes the timer piston 21 to the left, and a timer spring 25 is mounted in the timer low-pressure chamber 24 on the left side of the timer piston 21 against it. The timer low pressure chamber 24 communicates with the suction port of the feed pump 8 by a flow path 26 and is always at a low pressure during operation. The oil pressure, that is, the supply pressure of the fuel acting on the timer high-pressure chamber 22 varies depending on the engine speed, and hence the rotational speed of the drive shaft 2, so that the urging force by the oil pressure and the urging force of the timer spring 25 The timer piston 21 moves to a position where the two are balanced, and the roller ring 10 is rotationally adjusted via the spherical bearing 33 and the slide pin 19, so that the fuel injection timing changes according to the engine speed. .
[0016]
A hydraulic control valve 27 is inserted between the timer high pressure chamber 22 and the timer low pressure chamber 24, and the timer high pressure chamber 22 is controlled by opening and closing the hydraulic control valve 27 electrically connected to the electronic control device 5. The hydraulic pressure inside is partially adjusted to escape to the timer low pressure chamber 24 side, and the position of the timer piston 21 and the rotational direction of the roller ring 10 are changed, thereby controlling the fuel injection timing.
[0017]
In FIG. 1, the aforementioned rotational speed sensor 4 is carried on the outer peripheral surface 10 a of the roller ring 10, and its output signal is input to the electronic control device 5. As shown in FIG. 1, a top dead center signal indicated as a TDC signal from the engine, an accelerator opening signal indicating the magnitude of the engine load, an output signal from a water temperature sensor that detects a cooling water temperature, and the like are input.
[0018]
The above is the description of the configuration common to the known part.
Next, returning to FIG. 2 again, the features of the present invention will be described. The timer cylinder 20 is provided with a first groove 36 and a second groove 37. The first groove 36 communicates with the inlet side of the hydraulic control valve 27 by a flow path 29. The second groove 37 communicates with the outlet side of the hydraulic control valve 27 and the timer low pressure chamber 24 by flow paths 30 and 31. A third groove 38 is formed in the timer piston 21 and communicates with the timer high pressure chamber 22 by a flow path 32.
[0019]
Next, the operation of the first embodiment of the present invention will be described with reference to FIGS.
In FIG. 2, the duty ratio control of the hydraulic control valve 27 is performed at 40 Hz, and when the energization duty is reduced, the amount of fuel flowing from the timer high pressure chamber 22 into the timer low pressure chamber 24 via the hydraulic control valve 27 decreases. And the timer piston 21 moves to the left in the figure against the urging force of the spring 25.
[0020]
Further, when the duty ratio to the hydraulic control valve 27 is reduced, the timer piston 21 further moves to the left side in the drawing, and the second groove 37 and the third groove 38 begin to communicate with each other as shown in FIG.
When the second groove 37 and the third groove 38 communicate with each other, the timer high pressure chamber 22 and the timer low pressure chamber 24 communicate with each other, so that the fuel in the timer high pressure chamber 22 flows through the flow path 32, the third groove 38, and the second groove 38. 2, the pressure in the timer high pressure chamber 22 decreases, and the timer piston 21 does not move to the left in FIG. Accordingly, the timer piston 21 does not collide with the timer low pressure chamber side cover 34 at the most advanced angle, and the noise is reduced.
[0021]
Next, in FIG. 2, the oil pressure control valve 27 is duty ratio controlled at 40 Hz, and when the energization duty is increased, the amount of fuel flowing from the timer high pressure chamber 22 into the timer low pressure chamber 24 via the oil pressure control valve 27 increases. The pressure in the chamber 22 becomes low, and the timer piston 21 moves to the right in FIG.
[0022]
Further, when the duty ratio to the hydraulic control valve 27 is increased, the timer piston 21 further moves to the right side in FIG. 2, and the first groove 36 starts to be blocked by the timer piston 21 as shown in FIG.
When the first groove 36 is cut off, the communication between the timer high pressure chamber 22 and the inlet side of the hydraulic control valve 27 is cut off, so that the pressure in the timer high pressure chamber 22 rises, and the timer piston 21 is further connected to FIG. It does not move to the middle right. Therefore, the timer piston 21 does not collide with the timer high pressure chamber side cover 35 at the most retarded angle, and the noise is reduced.
[0023]
FIG. 5 is a cross-sectional view showing the main configuration of a second embodiment of the timer device of the present invention.
This second embodiment is applied to a timer device of a timer low pressure chamber control system.
Since a considerable part of the structure shown in FIG. 5 is substantially the same as that of the timer device 28 of the timer high-pressure chamber control system shown in FIG. 2, the same reference numerals are used for them. .
[0024]
First, common parts with the prior art will be explained. In FIG. 5, the timer high pressure chamber 22 on the right side of the timer piston 21 is always in communication with the connection hole 39 that communicates with the fuel chamber 15 via the flow path 17 having the throttle 23 and is pressurized to about 10 atm by the feed pump 8. Is accepting fuel. A timer spring 25 is mounted in the timer low pressure chamber 24 on the left side of the timer piston 21. The timer low pressure chamber 24 communicates with the suction port of the feed pump 8 via a flow path 41 having a throttle 40. Further, the inlet side of the hydraulic control valve 27 and the fuel chamber 15 communicate with each other through the flow path 42. Further, the outlet side of the hydraulic control valve 27 and the timer low pressure chamber 24 communicate with each other through the flow path 43. By adjusting the amount of inflow from the fuel chamber 15 by the hydraulic control valve 27, the pressure of the timer low pressure chamber 24 (range from atmospheric pressure to the same 10 atmosphere as the fuel chamber 15) is determined. The position of the timer piston 21 is determined by the balance between the force generated by the pressure difference between the timer high pressure chamber 22 and the timer low pressure chamber 24 and the biasing force of the timer spring 25.
[0025]
The above is the description of the common part with the prior art in the configuration of the second embodiment.
Next, features of the second embodiment of the present invention will be described.
The timer cylinder 20 is provided with a fourth groove 44 and a fifth groove 45. The fourth groove 44 communicates with the suction port of the feed pump 8 through a flow path 48. The fifth groove 45 communicates with the outlet side of the hydraulic control valve 27 and the timer low pressure chamber 24 by flow paths 43 and 47. Further, the timer piston 21 is formed with a sixth groove 46 and communicates with the connection hole 39 by a flow path 49.
[0026]
Next, the operation will be described.
When the duty ratio to the hydraulic control valve 27 is reduced, the pressure in the timer low pressure chamber 24 is lowered, and the timer piston 21 moves to the left side in FIG. When the fifth groove 45 and the sixth groove 46 communicate with each other, the connection hole 39 communicated with the fuel chamber 15 and the timer low pressure chamber 24 communicate with each other. As a result, the fuel in the fuel chamber 15 flows into the timer low pressure chamber 24, so that the timer piston 21 does not move further to the left side, and noise generation due to the collision of the timer piston 21 with the timer low pressure chamber side cover 34 can be prevented.
[0027]
Further, when the duty ratio to the hydraulic control valve 27 is increased, the pressure in the timer low pressure chamber 24 is increased, and the timer piston 21 moves to the right side in FIG. When the fourth groove 44 and the timer low pressure chamber 24 communicate with each other due to the movement of the timer piston 21, the fuel in the timer low pressure chamber 24 flows out through the flow path 48, so that the timer piston 21 does not move further to the right side. This eliminates the occurrence of noise due to the collision of the timer piston 21 with the timer high pressure chamber side cover 35.
[0028]
The present invention can be applied not only to a face cam pressure feed type fuel injection pump but also to an inner cam pressure feed type fuel injection pump.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an overall configuration of a face cam type fuel injection pump showing a configuration common to a first embodiment and a second embodiment of the present invention.
FIG. 2 relates to the first embodiment of the timer device of the present invention, and is a cross-sectional view illustrating the configuration of the first embodiment.
FIG. 3 relates to the first embodiment of the timer device of the present invention, and is a sectional view for explaining the operation.
FIG. 4 relates to the first embodiment of the timer device of the present invention and is a sectional view for explaining the operation.
FIG. 5 is a cross-sectional view showing a second embodiment of the present invention.
FIG. 6 is a cross-sectional view showing a conventional face cam type fuel injection pump.
[Explanation of symbols]
6 Plunger 15 Fuel chamber 16 Fuel injection valve 20 Timer cylinder 21 Timer piston 22 Timer high pressure chamber 24 Timer low pressure chamber 27 Hydraulic control valve 28 Timer device 34 Timer low pressure chamber side cover 35 Timer high pressure chamber side cover 36 First groove 37 Second Groove 38 third groove 44 fourth groove 45 fifth groove 46 sixth groove

Claims (4)

Attached to a fuel injection pump for an internal combustion engine that pumps and injects fuel to a fuel injection valve by a reciprocating movement of a plunger, a timer cylinder, a timer high pressure chamber and a timer low pressure chamber formed at both ends of the timer cylinder, A timer piston that is slidably inserted into the timer cylinder and moves according to the differential pressure between the timer high pressure chamber and the timer low pressure chamber to adjust the fuel injection timing, and for changing the pressure of the timer high pressure chamber In the timer device comprising a hydraulic control valve, means for limiting the operating range of the timer piston by hydraulic pressure is provided , and the hydraulic control formed in the timer cylinder as means for limiting the operating range of the timer piston by hydraulic pressure The first groove communicating with the valve communicates with the timer high pressure chamber, and the timer piston is connected to the timer high pressure chamber side cover. The timer device of the fuel injection pump, characterized by being configured to be cut off by the movement of at the most retarded angle of the timer piston in front contact. In the timer device for changing the pressure of the timer high pressure chamber by the hydraulic control valve, as a means for limiting the operating range of the timer piston by oil pressure, a second groove formed in the timer cylinder and communicating with the timer low pressure chamber And a third groove that is formed on the slide surface of the timer piston and communicates with the timer high pressure chamber, the timer piston is in contact with the timer low pressure chamber side cover before the timer piston is in the most advanced angle. 2. The timer device for a fuel injection pump according to claim 1, wherein the timer device is configured to communicate with each other by movement . Attached to a fuel injection pump for an internal combustion engine that pumps and injects fuel to a fuel injection valve by a reciprocating movement of a plunger, a timer cylinder, a timer high pressure chamber and a timer low pressure chamber formed at both ends of the timer cylinder, A timer piston that is slidably inserted into the timer cylinder and moves according to the differential pressure between the timer high pressure chamber and the timer low pressure chamber to adjust the fuel injection timing, and for changing the pressure of the timer low pressure chamber In the timer device comprising a hydraulic control valve, means for limiting the operating range of the timer piston by hydraulic pressure is provided, and means for limiting the operating range of the timer piston by hydraulic pressure is formed in the timer cylinder and is connected to the low pressure side. The fourth groove communicating with the timer low pressure chamber is shut off so that the timer piston contacts the timer high pressure chamber side cover. Before the timer device for a fuel injection pump which is characterized by being configured as communicated by the movement of at the most retarded angle of the timer piston that. In the timer device for changing the pressure of the timer low pressure chamber by the hydraulic control valve, as means for limiting the operation range of the timer piston by oil pressure, a fifth groove formed in the timer cylinder and communicating with the timer low pressure chamber; The interruption with the sixth groove formed in the timer piston and communicating with the fuel chamber is communicated by the movement of the timer piston at the most advanced angle before the timer piston contacts the timer low pressure chamber side cover. 4. The fuel injection pump timer device according to claim 1 , wherein the timer device is configured as described above .

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