JP3447079B2 - Timer device for fuel injection pump - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a timer device for adjusting the injection timing of a fuel injection pump for an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, in order to adjust the fuel injection timing of a fuel injection pump, a roller ring 8 of a fuel injection pump 1'via a timer piston 28 positioned by the hydraulic pressure of a timer high pressure chamber 30 as shown in FIG. Of the fuel including a timer device 25 for controlling the rotational angle position of the timer and a hydraulic control valve 33 for controlling the hydraulic pressure of the timer high pressure chamber 30 which is opened and closed by a pulse drive signal with a varying duty ratio to determine the position of the timer piston 28. An injection timing control device is used.

[0003]

In the above conventional fuel injection timing control device, in the pressure stroke of the plunger 6,
Due to the compression reaction force of the fuel acting on the plunger 6, the timer piston 28 receives a force by the face cam 4 in the right direction in FIG. 3 via the slide pin 27, resulting in an increase in the pressure in the timer high pressure chamber 30. , The fuel in the timer high pressure chamber 30 flows back into the fuel chamber 17 through the throttle 34, and the timer piston 28 delays the fuel injection timing (right side in FIG. 3).
However, there was a problem that the injection pressure was lowered due to the movement to.
The problem to be solved by the present invention is, in the pressure feeding stroke of the plunger,
It is an object of the present invention to provide means for preventing an erroneous decrease in fuel injection pressure due to an increase in the pressure in the high pressure chamber of the timer device due to the compression reaction force of fuel.

[0004]

As a means for solving the above-mentioned problems, the present invention sucks the fuel in the fuel chamber pressurized by the fuel feed pump by the reciprocating motion of the plunger and applies it to a high pressure. In order to control the fuel injection timing of the fuel injection pump that pressurizes and intermittently feeds to the fuel injection valve of the internal combustion engine, one end of a timer piston that is reciprocally slidably inserted in a cylinder provided in the timer housing Forming a timer high pressure chamber into which the fuel pressure of the fuel chamber is introduced, and providing a hydraulic pressure control valve controlled by an electronic control device in a passage communicating between the timer high pressure chamber and the low pressure side. together with the fuel pressure regulating pressure, the timer device of the fuel injection pump so and cut off the communication between the low pressure side and the timer high-pressure chamber during pumping of the plunger There are, said between timer high-pressure chamber and said fuel chamber is provided with means for completely shutting off the communication to passage communicating at pumping of the plunger, during pumping of the plunger, the said timer high-pressure chamber by said means with completely block between the fuel chamber, by completely blocking even the communication between the timer high-pressure chamber and the low pressure side, and the timer high-pressure chamber to complete a closed room of state, the timer high-pressure A timer device for a fuel injection pump, characterized in that fuel in a room is confined in the room.

[0005]

In the fuel injection stroke of the fuel injection pump, when the position of the timer piston is about to shift due to the reaction force of the fuel to be pumped, the electronically controlled timer device of the fuel injection pump according to the present invention Is provided with a means for completely interrupting the communication state at the time of pressure feeding of fuel in a passage communicating between the timer high pressure chamber and the fuel chamber. Not only is the passage between them completely cut off, but it is premised that the communication between the timer high pressure chamber and the low pressure side is also completely cut off when the fuel is pumped.
The timer high pressure chamber is completely closed. Therefore, the fuel in the timer high pressure chamber loses its escape route and is confined in the timer high pressure chamber as it is. Since the fuel is an incompressible fluid, the timer piston cannot move in the direction that compresses the fuel trapped in the timer high-pressure chamber and is locked in that position. It is possible to prevent the injection pressure from decreasing.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. In FIG. 1, the fuel injection pump 1 of the present embodiment
Is a face cam pressure distribution type, and the drive shaft 2 is driven by an engine (not shown) and performs a rotary motion in synchronization with a rotation speed which is ½ of the engine rotation speed. A signal rotor 3 is fixed to the drive shaft 2 coaxially with the drive shaft 2. Further, a vane type pump 24 which is a fuel feed pump is attached to the drive shaft 2 and is connected to the face cam 4 via a coupling (not shown). The face cam 4 is integrated with the plunger 6 by the spring 5, and is pressed against the roller 7. Therefore, when the face cam 4 is rotationally driven by the drive shaft 2, the coupling state between the roller 7 and the cam lobe of the face cam 4 changes, and the plunger 6 moves in the axial direction a number of times equal to the number of cylinders during one rotation. Reciprocates.

A pickup 9 is attached to the roller ring 8 so as to face the peripheral surface of the signal rotor 3. The signal rotor 3 is provided with a plurality of convex teeth at predetermined angles (for example, 5 °), and these convex teeth are cut out at equal intervals by the same number as the number of cylinders, and a toothless portion (for example, 3).
Tooth) is formed. Therefore, when the signal rotor 3 rotates, the convex teeth move toward and away from the pickup 9, so that the pickup 9 is moved by electromagnetic induction.
Outputs an NE pulse signal corresponding to the engine speed. The wide valley portion of the NE pulse signal (corresponding to the toothless portion of the signal rotor 3) acts as a reference position signal,
The other part acts as a rotation angle signal.

On the outer circumference of the plunger 6, one distribution port 10 and suction grooves 11 are formed in the same number as the number of engine cylinders. The tip end surface of the plunger 6 and the cylinder bore 12 are formed.
A pressure chamber 14 is formed between the pressure chamber 14 and the closing plug 13. The cylinder 15 and the casing 16 are formed with an intake passage 38 that communicates the fuel chamber 17 with the cylinder bore 12, and a distribution passage 19 that allows the injection valve 18 of each external cylinder to communicate with the cylinder bore 12. The distribution passages 19 are provided in the same number as the number of cylinders of the engine, and delivery valves 20 are provided in the middle thereof. Delivery valve 2
0 can be opened against the spring 21, and has a function as a check valve and a function as a suction and return valve.

Therefore, when the plunger 6 moves to the left in the drawing and the pressure chamber 14 expands, that is, in the intake stroke of the fuel injection pump 1, one of the intake grooves 11 is brought into conduction with the intake passage 38 and the fuel chamber 17 is opened. The fuel in the inside is sucked into the pressure chamber 14, and conversely, when the plunger 6 moves to the right in the figure and the pressure chamber 14 is compressed, that is, in the compression stroke, the distribution port 10 is used for any distribution. The pressurized fuel in the pressure chamber 14 is pressure-fed to the fuel injection valve 18 by passing through the passage 19. The timing at which the plunger 6 starts to move to the right is sufficiently earlier than the timing at which the injection valve 18 is requested to start injection, and the time to stop the plunger 6 from moving to the right is requested to stop injection at the injection valve 18. It is set to be sufficiently later than the time.

In the casing 16 of the fuel injection pump 1,
A spill valve 22 that controls the pressure of the pressure chamber 14 is provided, and the spill valve 22 controls the fuel injection start timing, the injection amount, and the injection rate of the fuel injection pump 1. As is well known, the electronic control unit 23 includes a CPU, RAM, ROM,
It is composed of an AD converter, an input port, an output port, and the like. A program for a control routine is stored in the ROM of the electronic control unit 23, and the N from the pickup 9 is stored in the ROM.
The spill valve 22 and the hydraulic control valve 33 are controlled according to the E pulse signal, the water temperature, the accelerator opening, the TDC signal from the TDC sensor attached to the engine (not shown), and the like.

Next, the timer device 25 is slidably fitted in the timer housing 26 and a cylinder 26 'formed in the timer housing 26, and is connected to the roller ring 8 and the slide pin 27 by a timer piston. 28 and a spring 29 for urging the timer piston 28 in the right direction in the figure, and by positioning the timer piston 28 by the fuel pressure of the timer high pressure chamber 30 into which the high pressure fuel in the fuel chamber 17 is introduced, Slide pin 27
The position of the roller ring 8 is determined via the, and the fuel injection timing is adjusted. Further, the fuel pressure in the timer high pressure chamber 30 is regulated by a hydraulic control valve 33 which is provided in a communication passage 32 between the timer high pressure chamber 30 and the timer low pressure chamber 31 and whose opening and closing is controlled by the electronic control unit 23. The above is the description of the known part.

Further, in this embodiment, the plunger 6
There are as many timer grooves 35 as there are cylinders of the engine, the cylinder bore 12 and the timer high pressure chamber 30 are connected by a timer passage 36, and a throttle 37 is provided in the middle of the timer passage 36. Establishing and blocking fluid communication between the fuel chamber 17 for supplying high pressure fuel to the timer channel 36 and timer high-pressure chamber 30 is effected by rotation of the plunger 6, the pressure Okutoki timer passage 36
(That is, the timer high pressure chamber 30) and the fuel chamber 17 are shut off.

Next, the operation of the first embodiment will be described with reference to FIGS. FIG. 2 is an operation explanatory view showing movements of the respective parts and the like corresponding to the passage of time in the first embodiment shown in FIG.

When the suction stroke of the plunger 6 is completed, the communication between the suction passage 38 and the pressure chamber 14 is cut off by the rotation of the plunger 6. After that, when the spill valve 22 is energized, the spill valve 22 is closed. Further, the rotation of the plunger 6 shuts off the timer groove 35 and the timer passage 36 as shown in FIG. (That is, the fuel chamber 17 and the timer high pressure chamber 30 are shut off.)

The fuel pressure in the pressure chamber 14 rises as the plunger 6 moves to the right, and when it reaches 160 kg / cm ² , which is the opening pressure of the injection valve 18 of each cylinder, fuel injection into the combustion chamber of a cylinder not shown. Is started. Plunger 6 after that
Continues to the right, and the pressure in the pressure chamber 14 further increases with the right. When the pressure in the pressure chamber 14 increases, the face cam 4 integrated with the plunger 6 receives the pressure of the fuel in the pressure chamber 14 in the leftward direction in FIG. 1, so that the timer piston 28 causes the roller 7, the roller ring 8, and Slide pin 2
A force is received in the right direction in the figure via 7 and the pressure in the timer high pressure chamber 30 increases. However, in the present embodiment, when the plunger 6 is pressure-fed, the timer high pressure chamber 30 and the fuel chamber 17 are
Is cut off and the hydraulic control valve 33 is not energized as shown in FIG.
It becomes in a closed state, since it is also blocked between the timer high-pressure chamber 30 and the timer low-pressure chamber 31, the timer high-pressure chamber 3
The fuel of 0 does not flow into the lower pressure fuel chamber 17 or the timer low pressure chamber 31, and the positions of the timer piston 28 and the roller ring 8 do not change, so that the injection pressure can be prevented from lowering.

When the spill valve 22 is de-energized when a predetermined fuel injection amount is obtained in the cylinder, the spill valve 22 opens, the pressure in the pressure chamber 14 and the distribution passage 19 decreases, and the injection ends. To do. When the pumping stroke of the plunger 6 is completed and the suction stroke is started, the suction groove 11 of the plunger 6 is set to 1
One can conduct through the suction passage 38 into the fuel chamber 17 the fuel pressurized to a pressure of the vane pump Therefore 5 kg / cm ² is filled, the fuel with the movement of leftward in the drawing the plunger 6 The fuel in the chamber 17 is sucked into the pressure chamber 14. In addition, when the intake stroke starts, the rotation of the plunger 6 causes
As shown in (b), the timer groove 35 and the timer passage 36 communicate with each other. (That is, the fuel chamber 17 and the timer high pressure chamber 30 communicate with each other.)

The electronic control unit 23 controls the timer high pressure chamber.
Hydraulic control valve 3 for adjusting the fuel pressure of 30
The energization of 3 is performed after the fuel chamber 17 and the timer high pressure chamber 30 communicate with each other. For example, as shown in FIG. 2C, the hydraulic control valve 33 is energized at the same time as the NE pulse signal # 12 to open it. Then, the energization period τ to the hydraulic control valve 33 is calculated by the electronic control unit 23 so that the fuel injection timing becomes the target fuel injection timing of the diesel engine, and after the energization period τ has elapsed, the hydraulic control valve 33.
Is turned off. As a result, the hydraulic control valve 33
Since the valve is closed, the timer high pressure chamber 30 and the timer low pressure chamber 31
Communication between the two is cut off, and when the plunger 6 is pumped,
The fuel in the high pressure chamber 30 flows into the timer low pressure chamber 31 and the timer
It is possible to prevent the pressure in the high pressure chamber 30 from decreasing.
It

A second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a diagram in which the present invention is applied to an inner cam pressure feed type distribution type fuel injection pump 51. First implementation described above
Similarly to the example , the drive shaft 52 is driven by an engine (not shown), and makes a rotary motion in synchronization with a rotation speed of ½ of the engine rotation speed. The drive shaft 52 has a vane type pump 5 which is a fuel feed pump.
3 is attached, and the signal rotor 54 is coaxially fixed to the drive shaft 52.

In the structure of the inner cam pressure distribution type fuel injection pump, the drive shaft 52 is connected to the distribution rotor 55 via a coupling (not shown). Plungers 56 are radially slidably inserted into a plurality of cylinders formed in the distribution rotor 55 in the radial direction. When the distribution rotor 55 is driven by the drive shaft 52 to rotate, the plunger 56, the roller receiver 57, and the roller 58 receive centrifugal force and are pressed against the inner cam 59. To be done. Therefore, the roller 5
8 and the cam ridge of the inner cam 59 are changed by the rotation of the drive shaft 52, and the plunger 56 is set to 1
It reciprocates with respect to the pressure chamber 60 a number of times equal to the number of cylinders during rotation.

The inner cam 59 includes a signal rotor 5
The pickup 61 is attached so as to oppose the peripheral surface of No. 4. The signal rotor 54 has a predetermined angle (for example, 5
A plurality of convex teeth are arranged for each .degree.), And the convex teeth are cut out at equal intervals by the same number as the number of cylinders to form a missing tooth portion (for example, 3 teeth). On the outer periphery of the distribution rotor 55, one distribution port 62 and suction grooves 63 are formed in the same number as the number of engine cylinders. In the cylinder 64,
Intake passage 6 that communicates the fuel chamber 66 with the cylinder bore 67.
8, a distribution passage 70 is formed in the cylinder 64 and the casing 65 so that the injection valve 69 of each external cylinder can be connected to the cylinder bore 67. The casing 65 of the fuel injection pump 51 includes a spill valve 7 for controlling the pressure of the pressure chamber 60.
1 is provided, and the spill valve 71 controls the fuel injection start timing, the injection amount, and the injection rate of the fuel injection pump 51.

Next, the timer device 72 is installed in the timer housing 73, and is connected to the inner cam 59 via the slide pin 74, a timer piston 75, a cylinder 73 'for receiving the timer piston 75, and the timer piston 7.
The position of the inner cam 59 is determined by positioning the timer piston 75 by the fuel pressure in the timer high pressure chamber 77, which is constituted by a spring 76 for urging 5 in the right direction in the drawing and into which high pressure fuel in the fuel chamber 66 is introduced. Is determined and the fuel injection timing is adjusted. Further, the fuel pressure in the timer high pressure chamber 77 is regulated by a hydraulic pressure control valve 84 which is provided in a communication passage 79 between the timer high pressure chamber 77 and the timer low pressure chamber 78 and whose opening / closing is controlled by an electronic control unit 80.

Further, in the second embodiment, the distribution rotor 55 is provided with the same number of timer grooves 81 as the number of engine cylinders, the cylinder bore 67 and the timer high pressure chamber 77 are connected by the timer passage 82, and the throttle 83 is connected to the timer passage. 8
It is provided in the middle of 2. Establishing and blocking fluid communication between the timer passage 82 and the fuel chamber 66 is performed by the rotation of the distributor rotor 55, the pressure Okutoki the plunger 56, a timer channel 82 (i.e., the timer high-pressure chamber 77) between the fuel chamber 66 Be cut off. When the plunger 56 is being pumped, the hydraulic control valve
Since 84 is not energized, the hydraulic control valve 84 is closed.
Between the timer high pressure chamber 77 and the timer low pressure chamber 78
Has also been cut off.

The operation of the timer device 72 in the second embodiment is almost the same as the operation of the timer device 25 in the first embodiment. The different point is that in the first embodiment, the communication between the fuel chamber 17 and the timer high-pressure chamber 30 is performed by the rotation of the plunger 6 that pressurizes the fuel, but in the second embodiment, the fuel chamber 66 and the timer. That is, the communication with the high pressure chamber 77 and the disconnection are performed by the rotation of the distribution rotor 55.

[0024] The third embodiment of the present invention will be described with reference to FIG. In FIG. 5 , the timer device 25 is the timer high pressure chamber 3
By controlling the hydraulic pressure of 0 using the hydraulic control valve 33, the position of the timer piston 28 is determined and the rotational angular position of the roller ring 8 of the fuel injection pump similar to that shown in FIG. 1 is controlled. In this embodiment, the fuel chamber supplying the high pressure fuel to the timer high pressure chamber 30 and the timer high pressure chamber 30.
By newly providing a check valve 40 (set so as to open with a pressure difference of 0.1 atm) in the passage 39 connecting with the timer high pressure chamber 30 in the pressure stroke of the plunger 6 (see FIG. 1). When the pressure becomes high, the fuel does not flow back into the fuel chamber 17 through the passage 39. Therefore, the amount by which the timer piston 28 moves to the right side in FIG. 5 can be reduced, which can prevent the injection pressure from decreasing. Needless to say, check valve 40
The third embodiment using the above can also be applied to the inner cam pressure feed type distribution type fuel injection pump as shown in the second embodiment (FIG. 4 ).

As a modification of the first and second embodiments, the timer low pressure chambers 31 and 78 and the timer high pressure chambers 30 and 7 are shown.
7 through the plunger 6 or a timer groove provided in the distribution rotor 55.
Alternatively, the fuel chambers 17, 66 are rotated by the rotation of the distribution rotor 55.
It is also possible to connect / disconnect with respect to, and by doing so, similarly, it is possible to prevent the injection pressure from decreasing.

[0026]

According to the present invention, the fuel injection pump electronic
By adding a simple means to controlled timing device, Taimapisu when feed pressure of the plunger of the fuel injection pump
The communication between the high pressure chamber and the fuel chamber on one side of the ton is blocked.
At the same time as disconnecting, the communication between the timer high pressure chamber and the low pressure side
Also, the timer high pressure chamber is completely closed.
Thus, the position of the timer piston of the timer device is prevented from being displaced due to the compression reaction force of the fuel at the time of the pressure feeding, and the erroneous decrease of the fuel injection pressure caused thereby is prevented .
In addition, since it can be reliably prevented, the internal combustion engine can sufficiently exhibit the desired output performance.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a time chart for explaining the operation of the first embodiment.

FIG. 3 is a cross-sectional view illustrating a conventional technique.

FIG. 4 is a sectional view showing a second embodiment of the present invention.

FIG. 5 is a sectional view showing a third embodiment of the present invention.

[Explanation of symbols]

1, 1 ', 51 ... Fuel injection pump 4 ... Face cam 6 ... Plunger 14, 60 ... Pressure chamber 17, 66 ... Fuel chamber 18, 69 ... Fuel injection valve 22, 71 ... Spill valve 23, 80 ... Electron Type control device 24, 53 ... Vane type pump (fuel feed pump) 25, 72 ... Timer device 26, 73 ... Timer housing 27, 74 ... Slide pin 28, 75 ... Timer piston 30, 77 ... Timer high pressure chamber 31, 78 ... Timer low pressure chamber 33, 84 ... Hydraulic control valve 34 , 37 , 83 ... Restrictor 35 , 81 ... Timer groove 36, 82 ... Timer passage 40 ... Check valve 55 ... Distribution rotor 56 ... Plunger 59 ... Inner cam

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuyuki Sakakibara 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Japan Automotive Parts Research Institute, Inc. (56) Reference JP-A-1-29632 (JP, A) JP-A 63-57828 (JP, A) JP-A-4-284156 (JP, A) JP-A-5-214998 (JP, A) JP-B 44-26489 (JP, B1) JP-B 38-23551 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) F02M 41/12 F02M 41/14

Claims (3)

(57) [Claims] 1. A fuel for a fuel injection pump, which sucks fuel in a fuel chamber pressurized by a fuel feed pump by reciprocating motion of a plunger, pressurizes it to a high pressure, and intermittently feeds it to a fuel injection valve of an internal combustion engine. In order to control the injection timing, a timer high pressure chamber into which the fuel pressure of the fuel chamber is introduced is formed at one end of a timer piston that is reciprocally slidably inserted in a cylinder provided in the timer housing.
A hydraulic control valve controlled by an electronic control device is provided in a passage communicating between the timer high pressure chamber and the low pressure side to regulate the fuel pressure in the timer high pressure chamber, and at the time of pressure feeding of the plunger, the timer high pressure chamber In a timer device for a fuel injection pump, which is configured to always shut off communication with the low pressure side, a communication state is completely established during pressure feeding of the plunger to a passage communicating between the timer high pressure chamber and the fuel chamber.
Means for blocking is provided at the time of pumping the plunger,
With completely block between the fuel chamber and the timer high-pressure chamber by said means, by completely blocking even the communication between the timer high-pressure chamber and the low pressure side, complete the timer high-pressure chamber A timer device for a fuel injection pump, characterized in that the fuel in the timer high-pressure chamber is confined in the closed chamber in a closed state. 2. The means, which is provided in a passage that connects the timer high-pressure chamber and the fuel chamber and completely cuts off the communication state when the plunger is pumped, is pressurized to a high pressure during the pumping. When the timer piston moves to the timer high pressure chamber side via the plunger in response to the reaction force of the fuel and the pressure of the timer high pressure chamber becomes higher than the pressure of the fuel chamber, the timer high pressure chamber and the timer high pressure chamber The timer device for a fuel injection pump according to claim 1, wherein the timer device is configured to completely cut off communication with the fuel chamber. 3. The means for completely interrupting the communication state when the plunger is pumped is provided in a passage communicating between the timer high pressure chamber and the fuel high pressure chamber. The timer device for a fuel injection pump according to claim 1 or 2, wherein the timer is a check valve that allows the flow of fuel while blocking the flow of fuel from the high pressure chamber to the fuel chamber. .