JPH11132128A - Variable delivery rate high pressure pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of noise caused by colliding of an inner cam and a cam roller with each other when a delivery rate is zero. SOLUTION: All axial direction of a plunger 21 are set to 30 deg. to 150 deg. to an action direction (a vertical line direction) of a gravity. As a result, respective movement of a plunger 21, a cam roller 22, and a shoe 24 is prevented by friction between plungers 21a to 21d (21) and a sliding hole 2 formed as a cylinder, without lowering by the gravity, and an inner cam 8 and the cam roller 22 do not collide with each other and thereby, noise is reduced when a delivery rate is zero. When four plungers 21 are arranged, the axial direction of the plunger 21 is set to about 45 deg. and about 135 deg. to the action direction (a vertical line direction) of the gravity. When two plungers 21 are arranged, the axial direction of the plunger 21 is set to about 90 deg. to the action direction (a vertical line direction) of the gravity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a common rail type fuel injection device for injecting high pressure fuel accumulated in a common rail (accumulation pipe) into each cylinder of a diesel engine by an injector. And a variable discharge high pressure pump.

[0002]

2. Description of the Related Art A common rail injection system is known as one of the systems for injecting fuel into a diesel engine. In the common rail injection system, a common pressure accumulation pipe (common rail) communicating with each cylinder is provided, and a variable discharge high pressure pump is used to supply high-pressure fuel at a required flow rate to thereby keep the fuel pressure in the pressure accumulation pipe constant. keeping. The high-pressure fuel in the pressure accumulating pipe is injected into each cylinder by an injector at a predetermined timing (for example, Japanese Patent Application Laid-Open No. 64-73166).

FIG. 8 is a cross-sectional view of an essential part showing an example of such a conventional variable discharge high pressure pump. In FIG. 8, a plunger 92 driven by a cam (not shown) is reciprocally fitted into a cylinder 91, and a pressure chamber 93 is formed between the inner wall surface of the cylinder 91 and the upper end surface of the plunger 92.
Is formed. An electromagnetic valve 94 is mounted above the pressure chamber 93. The electromagnetic valve 94 has a valve body 96 that opens and closes a space between a low-pressure flow path 95 and a pressure chamber 93 formed therein.

The valve body 96 is in the valve-opening position in the state shown in the drawing, in which the coil 97 is not energized. When the plunger 92 is lowered, the fuel is supplied from the low-pressure supply pump (not shown) to the low-pressure flow path 95 and the gap around the valve body 96. Through the pressure chamber 93. When the coil 97 is energized, the valve body 96 is attracted upward, and its substantially conical tip sits on the seat portion 98 to close the valve. At the same time, the fuel in the pressure chamber 93 is pressurized by the rise of the plunger 92, and is sent to the pressure accumulating pipe from the flow path 99 provided on the side wall of the pressure chamber 93.

When the plunger 92 is raised, a force in the valve closing direction acts on the valve body 96 due to the fuel pressure in the pressure chamber 93. Therefore, once the valve body 96 is closed, energization of the coil 97 is stopped. Even if it does not open. For this reason, in the variable discharge high-pressure pump having the above-described configuration, the control of the flow rate sent to the pressure accumulating pipe is performed by so-called pre-stroke control, which is controlled by adjusting the valve closing timing. That is, after the plunger 92 moves to the rising stroke, the valve is not closed immediately, the valve is kept open until the fuel in the pressure chamber 93 reaches a predetermined amount, and excess fuel is released to the low-pressure flow path 95 side, After a while
By closing the valve and starting pressurization, a required amount of pressurized fluid is pumped to the accumulator pipe.

However, when the oil feed rate of the pump increases with an increase in the engine speed, there arises a problem that the valve 96 closes (self-closes) regardless of the valve closing signal. This is because when the plunger 92 is raised, the valve body 96
Receiving the dynamic pressure of the fuel in the pressure chamber 93 directly on the lower end face;
This is due to, for example, receiving a force in the valve closing direction due to the throttle effect of fuel flowing from the gap between the valve body 96 and the seat portion 98 toward the low-pressure flow path 95, and the flow rate control may not be properly performed.

As a countermeasure, it is conceivable to increase the operating stroke of the valve body 96 or to increase the return spring force of the valve body 96, but in any case, the valve closing response is reduced. In order to maintain the valve-closing response, it is necessary to increase the amount of power supplied to the coil or increase the size of the coil to increase the attraction force of the solenoid valve, which increases the power cost and manufacturing cost of the solenoid valve. There was a problem.

In the variable discharge high-pressure pump having the above-described structure, the flow path to the pressure chamber 93 is opened and closed by the solenoid valve 94, and the valve body 96 is seated in response to a valve closing signal to close the flow path. Since a certain period of time is required until this time, usually, the operation response time is calculated in advance to control the valve closing timing.
However, when the rotation speed of the engine increases and the oil supply rate of the pump increases, the opening / closing operation cannot be performed in time, and there is a possibility that sufficient control cannot be performed.

Accordingly, the present inventors have made it possible to easily and reliably control the flow rate of pressure-feeding to the pressure accumulating pipe even when the engine speed is increased and the oil supply rate of the pump is high. For the purpose of not increasing the pressure, a valve body that opens and closes between the low-pressure flow path and the pressure chamber and a valve body that controls the flow rate of the low-pressure fuel drawn into the pressure chamber from the low-pressure flow path are separately provided. Proposed variable discharge high pressure pump (Japanese Patent Application No. 9-
No. 100939).

FIG. 9 is a cross-sectional view taken along a central axis showing a configuration of a variable discharge high pressure pump proposed by the present inventors in Japanese Patent Application No. 9-100939. In FIG.
A drive shaft 101 is provided in the pump housing 100.
The low-pressure fuel flows into the fuel pool 105 from the low-pressure channels 103 and 104 by a feed pump 102 that rotates integrally with the drive shaft 101.

At the right end of the drive shaft 101, an inner cam 106 is formed integrally. In the inner cam 106, the left end of the head 107 is inserted. In the left end of the head 107, sliding holes 108 forming four cylinders are formed radially (only two of them are shown in the figure), and a plunger 109 is reciprocally movable in each sliding hole 108. It is supported by. A pressure chamber 110 is formed by the inner end surface of the plunger 109 and the inner wall of the sliding hole 108, and pressurizes the introduced fuel by reciprocating the plunger 109.

In the flow path from the fuel reservoir 105 to the pressure chamber 110, an electromagnetic valve 111 for controlling the flow is provided from the upstream side.
And a check valve 112 are provided. The check valve 112 is opened by the pressure of the inflowing fuel while the solenoid valve 111 is open, and is closed when the solenoid valve 111 is closed. Thus, the required flow rate is previously adjusted by the solenoid valve 111 to the pressure chamber 110.
When the low pressure fuel is supplied to the solenoid valve 111, the flow path to the pressure chamber 110 is closed by the check valve 112 from the start of pressurization of the low-pressure fuel to the end of the pumping. ) Only works. Therefore, the solenoid valve 111
There is no need to increase the physique of the user, and the cost can be reduced.

[0013]

FIG. 10 is a cross-sectional view taken along the line CC in FIG. 9 showing the inner cam 106 and the like as viewed from the front, showing a zero discharge amount (the solenoid valve 111 is not energized. FIG. 13 is a sectional view taken along the line C-C showing an operation state when the valve body 113 is closed and the discharge amount is zero), and (A) shows a state immediately after the suction stroke is completed and immediately before the pressure feeding stroke is started;
(B) shows the state of the plunger, cam roller, and shoe immediately after (A), and (C) shows the state immediately before the pressure feeding stroke is completed and the suction stroke is started.

As shown in FIGS. 9 and 10, in this variable discharge high pressure pump, a sliding hole 108 serving as a cylinder formed in a head 107 is fixed.
06 rotates. In FIG. 10, as shown in FIG. 10A, when the discharge amount is zero, the cam roller 114 is separated from the inner cam 106. Therefore, four plungers 1
09, the cam rollers 114, and the shoes 115, the plungers 109a and 109c and the cam rollers 114a and 114
c, the shoes 115a and 115c are lowered by gravity, and the state shown in FIG. At this time, the volume of the pressure chamber 110 does not change. The rotation of the inner cam 106 causes the inner cam 106 and the cam roller 114c to collide with each other, and causes the plungers 109a and 109c and the cam roller 1 to rotate.
14a and 114c and the shoes 115a and 115c are raised to the state shown in FIG. Also at this time, the pressure chamber 110
Since there is no change in the volume, no discharge is performed from the variable discharge amount high-pressure pump, but a problem occurs in which the inner cam 106 and the cam roller 114c collide with each other to generate a metallic noise.

When the discharge is performed from the variable discharge amount high pressure pump, the inner cam 106 and the cam roller 11
Although it is inevitable that noise will be generated by the collision of 4, the generation of metallic and unpleasant noise even at the time of zero discharge amount will greatly reduce the commercial value. SUMMARY OF THE INVENTION It is an object of the present invention to provide a variable discharge amount high pressure pump that does not generate noise due to collision between an inner cam and a cam roller when the discharge amount is zero.

[0016]

In order to solve the above-mentioned problems, the present invention employs the technical means described in claims 1 to 3. According to the first aspect of the present invention, since all the axial directions of the plunger are arranged to be 30 ° to 150 ° with respect to the direction of action of gravity (vertical direction), the plunger and the cylinder barrel slide. By friction with moving hole,
The movement of the plunger, the cam roller, and the shoe is hindered, and the plunger does not move down due to gravity. The inner cam and the cam roller do not collide with each other, so that noise at the time of zero discharge can be reduced.

According to the second aspect of the present invention, there are four plungers, and the axial directions of the plungers are arranged at about 45 ° and about 135 ° with respect to the direction of action of gravity (vertical direction). Therefore, the friction force between the four plungers and the sliding hole acting as a cylinder acts equally, and the movement of the plunger, the cam roller, and the shoe is hindered under optimal friction conditions.
Since the inner cam does not descend due to gravity and does not collide with the cam roller, noise at the time of zero discharge amount can be reduced.

According to the third aspect of the present invention, the number of plungers is two, and the axial direction of the plungers is disposed at about 90 ° with respect to the direction of gravity (vertical direction). The friction force with the sliding hole as a cylinder acts equally on each of the two plungers, and the movement of the plunger, the cam roller, and the shoe is hindered under the optimal friction conditions, and the inner cam and the cam roller do not descend due to gravity. Since there is no collision, noise at the time of zero discharge amount can be reduced.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the variable discharge high pressure pump of the present invention is applied to a common rail injection system of a diesel engine will be described below. 1 to 5
FIG. 1 relates to the first embodiment of the present invention when there are four plungers 21. FIG. 1 is a cross-sectional view taken along a central axis showing a configuration of a variable discharge high pressure pump, and FIG. Fig. 3 is a system diagram in which a high-pressure high-pressure pump is applied to a common rail injection system of a diesel engine.
FIG. 4 is an enlarged cross-sectional view of the vicinity of the solenoid valve 6, and FIG. 4 is a vertical cross-sectional view showing the state of operation at zero discharge when the inner cam 8 is viewed from the front in section AA in FIG. A)
Shows the state just before the suction stroke is completed and just before the pumping stroke is started, and FIG. 2B shows the state just before the pressure feeding stroke is ended and just before the suction stroke is started. FIG. 5 is a time chart showing the operation of the common rail injection system of the present embodiment.

In the system diagram of FIG. 2, the engine E is provided with a plurality of injectors I corresponding to the combustion chambers of the respective cylinders, and these injectors I are connected to a common high-pressure accumulating pipe or a common rail R common to the respective cylinders. . The injection of fuel from the injector I into each combustion chamber of the engine E is as follows:
Controlled by ON-OFF of the injection control solenoid valve B1,
While the injection control solenoid valve B1 is open, the fuel in the common rail R is injected into the engine E by the injector I. Therefore, it is necessary to continuously accumulate fuel of a high predetermined pressure corresponding to the fuel injection pressure in the common rail R,
For this purpose, the variable discharge high pressure pump P of the present invention is connected via a supply pipe R1 as a high pressure flow path and a discharge valve B2.

The variable discharge high pressure pump P presses the low pressure fuel sucked from the fuel tank T via the feed pump P1 to a high pressure, and controls the fuel in the common rail R to a high pressure. The common rail R is provided with a pressure sensor S1 for detecting a common rail pressure, and an electronic control unit ECU serving as control means for controlling the system includes:
The discharge amount of the variable discharge amount high-pressure pump P is controlled so that the signal from the pressure sensor S1 becomes an optimum value set in advance according to the load and the rotation speed. Further, the electronic control unit E
The CU receives, for example, information on the number of revolutions and the load from the engine speed sensor S2 and the load sensor S3, and the electronic control unit ECU determines the optimal injection timing and injection according to the engine state determined by these signals. Amount (injection period)
And outputs a control signal to the injection control solenoid valve B1.

Next, the details of the variable discharge amount high pressure pump P will be described with reference to FIG. In FIG. 1, a drive shaft D that is rotationally driven in synchronization with a half rotation of the engine by an engine E (see FIG. 2) is inserted and held in a pump housing 1, and the drive shaft D Vane type feed pump P for supplying low pressure fuel
1 are connected. The feed pump P1 rotates integrally with the drive shaft D, draws fuel from the fuel tank T (see FIG. 2), and pressurizes the fuel pressurized to a low pressure in the low-pressure flow path 11,
The fuel is delivered to the fuel pool 52 through 12, 13, and 51. The fuel discharge side and the fuel suction side of the feed pump P1 are connected via a pressure adjusting valve (not shown) so that the discharge pressure can be adjusted. Thus, in this embodiment,
The variable discharge high pressure pump P has a configuration in which the feed pump P1 shown in FIG. 2 is built.

The drive shaft D has a bearing D
1, and D2, it is rotatably supported by the pump housing 1, and at the right end thereof, an inner cam 8 described later in detail is integrally formed. In the present embodiment, the drive shaft D and the inner cam 8 are integrated, but they may be separately provided and connected by a joint.

A head 14 is fitted into the opening at the right end of the pump housing 1, and the head 14 is inserted into the inner cam 8 with its central left end protruding. A plurality of plungers 21 are reciprocally and slidably fitted in sliding holes 2 serving as cylinders provided in the center of the left end of the head 14, and each plunger 21 is in sliding contact with the inner end face of each plunger 21. A pressure chamber 23 is formed between the hole 2 and the inner wall surface. The pressure chamber 23 communicates with the fuel reservoir 52 via the flow path 15, the check valve 4, and the solenoid valve 6, and
2 functions as a pressurizing chamber for pressurizing the fuel into which low-pressure fuel flows.

In FIG. 1, a lock adapter 5 in which the fuel reservoir 52 is formed is fixed to the right end face of the head 14. The fuel pool 52 is filled with low-pressure fuel pressurized to about 15 atm by the feed pump P1. The low-pressure fuel flows into the pressure chamber 23 through the lock adapter 5 and a flow path provided in the head 14. I do. In the middle of the flow path from the fuel pool 52 to the pressure chamber 23, the check valve 4 is disposed by being sandwiched between the lock adapter 5 and the head 14.
Fuel flows only in three directions. At the right end of the lock adapter 5, an electromagnetic valve 6 for controlling the amount of low-pressure fuel flowing into the pressure chamber 23 is provided.
Is fixed by inserting a bolt (not shown) through a flange 63 provided on the outer periphery of the valve housing 61. The solenoid valve 6 and the check valve 4 constitute the discharge control device P2 in FIG.

As shown in FIG. 3, the check valve 4 has a flow path 43 penetrating the housing 42 in the left-right direction, and a valve body 44 for opening and closing the flow path 43. The flow path 43 expands in the direction of the pressure chamber 23 (to the left in the figure) on the way to form a conical seat surface 45, and the valve body 44 is moved rightward by a spring 46 held in a spring stopper 41. Biased toward
It is seated on the seat surface 45. As described above, the check valve 4 is closed in the illustrated normal state, and when the solenoid valve 6 is opened and low-pressure fuel flows from the fuel reservoir 52, the valve body 44 is opened by the fuel pressure. It is done.

The solenoid valve 6 has a housing 61 containing a coil 62 and a valve body 71 fitted and fixed in the left end thereof. A valve body 73 is slid in a cylinder 72 provided in the valve body 71. It is movably held. Valve element 7
An annular flow path 74a is formed around the left end of the check valve 3. The flow path 74a communicates with the fuel reservoir 52 through a flow path 74b and the flow path 43c of the check valve 4 through a flow path 74c. Communicating.

An armature 64 is press-fitted and fixed to the right end of the valve body 73. The armature 64 faces the stator 65 at a fixed interval. The coil 62 is arranged on the outer periphery of the stator 65, and a spring 67 is arranged in a spring chamber 66 provided inside the stator 65, and urges the armature 64 to the left in the drawing. Channel 74
A substantially conical seat surface 75 is formed at the open end of the valve body c.
3 is seated on the seat surface 75 and the flow path 74
a and 74c are closed. Coil 62
When power is supplied to the armature 64, the armature 64 is sucked, and the tip end of the valve body 73 integrated therewith separates from the seat surface 75 to form the flow passage 74.
Open between a and 74c. As described above, the electromagnetic valve 6 is configured to be closed in a non-energized state, so that there is an effect of preventing the fuel from being pumped when the coil is damaged.

In FIG. 4, the plurality of plungers 2
Numerals 1 are arranged at equal intervals inside the ring-shaped inner cam 8. A shoe 24 is provided on the outer end of each plunger 21.
The cam roller 22 is rotatably held by each shoe 24. On the inner peripheral surface of the inner cam 8,
A cam surface 81 having a plurality of equally spaced cam ridges is formed.

As described above, in the present embodiment, the plungers 21c and 21d are operated in the direction of gravity (vertical direction).
At an angle of approximately 45 ° to the plunger 2
Since 1a and 21b are arranged at approximately 135 °,
The movement of the plunger 21, the cam roller 22, and the shoe 24 is hindered by the friction between the plunger 21 and the sliding hole 2 serving as the cylinder of the head 14 as shown in FIG. Even if the state shown in FIG.
The cam rollers 22 do not collide with each other, but only touch slightly. Therefore, noise at the time of zero discharge amount can be reduced.

In the present embodiment, the plungers 21c and 21d are arranged at 45 ° with respect to the direction of action of gravity, and the plungers 21a and 21b are arranged at 135 ° with respect to the direction of gravity. The angle may be about 30 ° to 150 °, which is an angle at which the plunger 21 does not move due to friction in the sliding hole 2. In FIG. 1, the plunger 21, the cam roller 22, the shoe 24, and the like show a BB cross section in FIG. 4A.

In the conventional variable discharge high pressure pump,
In many cases, a spring that constantly presses the plunger 21 against the cam 8 is provided. However, the variable discharge high-pressure pump of the present invention employs a suction amount control method, and when the plunger 21 descends to the lowest point when the suction amount is small, Cavitation may occur due to decompression of the pressure chamber 23. Therefore, in the present invention, no spring is provided, and the reciprocating movement of the plunger 21 is performed by a cam lift by rotation of the drive shaft D at the time of pressure feeding, and by the pressure (feed pressure) of low-pressure fuel at the time of suction. Therefore, when the suction amount is small, the plunger 21 moves only by the amount of the supply of the low-pressure fuel, and the cam roller 22 and the inner cam 8 are separated.

As shown in FIG. 1, the fuel pressurized in the pressure chamber 23 is supplied to a discharge hole 16 formed in the wall of the pump housing 1.
The delivery valve 3 (corresponding to the discharge valve B2 in FIG. 2) is supplied to the common rail R through the supply pipe R1 (see FIG. 2). The supply pressure varies depending on the operation state of the engine E, and is 200 to 1200 atm. The delivery valve 3 has a function as a check valve, has a valve body 31 and a return spring 32 for urging the valve body 31 in a valve closing direction, and opens when the pressurized fuel exceeds a predetermined pressure. .

Next, the operation of the common rail injection system having the above-described configuration will be described with reference to FIGS. In FIG. 5, the NE pulse is a waveform obtained by shaping the output signal from the engine speed sensor S2 in FIG. 2 in the electronic control unit ECU. The electronic control unit ECU controls the energization of the coil 62 of the solenoid valve 6 based on the NE pulse and signals from the load sensor S3, the pressure sensor S1, and a water temperature sensor and an atmospheric pressure sensor (not shown).

At a point (a) in FIG. 5, the coil 62 of the solenoid valve 6 in FIG. 1 is not energized, and the valve body 73 is closed by the urging force of the spring 67, so that the fuel pool The flow path 74c downstream of the valve body 52 and the valve body 73 is shut off.
The valve body 44 of the check valve 4 is closed by the urging force of the spring 46. In the state of point (a) in FIG.
The cam roller 22 and the inner cam 8 are separated.

When the pumping stroke starts, the lift of the inner cam 8 is started. Even when the inner cam 8 starts to lift, the plunger 21 does not immediately start rising, and when the lift amount of the inner cam 8 becomes the lift amount of the plunger 21 (point (b) in FIG. 5), the cam roller 22 is The cam roller 22 comes into contact with the inner cam 8 and pushes up the plunger 21 via the shoe 24. In this pressure feed stroke, the check valve 4 is pressurized, so that the valve body 44 does not open. Thereafter, the volume in the pressure chamber 23 decreases with the rise of the plunger 21, and the pressure in the pressure chamber 23 gradually increases. When the pressure of the fuel in the pressure chamber 23 exceeds a predetermined pressure, the supply pipe R passes through the passage 16 and the delivery valve 3.
1 supplies high-pressure fuel to the common rail R (see FIG. 2). When the lift of the plunger 21 becomes maximum (point (c) in FIG. 5), the pressure feeding ends.

After the completion of the pressure feeding, the suction process is started. The electronic control unit ECU controls the energization of the coil 62 so that the solenoid valve 6 starts to open and enters the suction stroke and is fully opened at the same time. After the point (c) in FIG. 5, the suction stroke starts, and the valve element 73 of the solenoid valve 6 is open, so that the low-pressure fuel flowing from the fuel reservoir 52 into the flow path 74 c resists the force of the spring 46. Then, the valve body 44 of the check valve 4 is opened, and flows into the pressure chamber 23. At this time, the plunger 21 is pushed down by the inflowing fuel, and the fuel is sucked until the solenoid valve 6 is closed.

When the energization of the coil 62 from the electronic control unit ECU is interrupted, the valve body 73 of the solenoid valve 6 closes (point (d) in FIG. 5), and the gap between the fuel reservoir 52 and the flow path 74c is reduced. That is, the connection with the pressure chamber 23 is shut off. When the fuel stops flowing, the valve body 44 of the check valve 4 is also closed by the urging force of the spring 46. Thereafter, the cam surface of the inner cam 8 continues to descend, but when the suction is completed, the lift of the plunger 21 stops, and the cam roller 22 and the inner cam 8 separate.

Here, the amount of fuel supplied from the fuel reservoir 52 to the pressure chamber 23 is controlled by the time of energizing the coil 62 of the solenoid valve 6. The dotted line in FIG. 5 indicates a case where the supply amount is large, the plunger 21 descends to the lowest point, and the maximum amount of fuel is sucked into the pressure chamber 23. Valve body 7 of solenoid valve 6
When the valve closing timing of 3 is advanced, as shown by the solid line in FIG.
The lowering of the plunger 21 stops halfway, and the fuel flowing into the pressure chamber 23 decreases.

FIG. 6 shows a second embodiment of the present invention in which two plungers 21 are provided. The inner cam 8 is viewed from the front at a position corresponding to a section AA in FIG. It is a longitudinal cross-sectional view which shows a mode of operation | movement, (A) has shown the state just before the suction stroke is completed and just before it enters into a pumping stroke, and (B) shows the state just before the pressure feeding stroke is ended and just before it enters a suction stroke. As shown in FIG. 6, when the number of plungers 21 is two, the plungers 21 are preferably arranged at substantially 90 degrees with respect to the direction of gravity (vertical direction).

FIG. 7 relates to a third embodiment of the present invention in which four plungers 21 are provided, and shows a cross section A- in FIG.
FIG. 6 is a longitudinal sectional view showing an operation state at the time of zero discharge amount when the inner cam 8 is viewed from the front at a position corresponding to A, and shows a state immediately before the suction stroke ends and the pressure feeding stroke ends. As shown in FIG. 7, depending on the engine E to which the variable discharge high pressure pump is mounted, it may be mounted at an angle.
In this case, the engine E
In this state, the plungers 21c and 21d are arranged at about 45 ° with respect to the direction of action of gravity (vertical direction), and the plungers 21a and 21b are arranged at about 135 °.

[Brief description of the drawings]

FIG. 1 relates to the first embodiment of the present invention when there are four plungers 21, and is a cross-sectional view along a central axis showing a configuration of a variable discharge high pressure pump.

FIG. 2 relates to the first embodiment of the present invention when there are four plungers 21, and is a system diagram in which the variable discharge high pressure pump of FIG. 1 is applied to a common rail injection system of a diesel engine.

FIG. 3 is an enlarged cross-sectional view of the vicinity of the check valve 4 and the solenoid valve 6 in FIG. 1 according to the first embodiment of the present invention when there are four plungers 21;

4 relates to the first embodiment of the present invention when there are four plungers 21. In the section AA in FIG. 1, the operation of the inner cam 8 when the discharge amount is zero when viewed from the front is shown. It is a longitudinal cross-sectional view which shows a state, (A) shows the state immediately before the suction stroke is completed and immediately before the pumping stroke is started, and (B) shows the state immediately before the pressure feeding stroke is ended and immediately before the suction stroke is started.

FIG. 5 relates to the first embodiment of the present invention when there are four plungers 21, and is a time chart showing the operation of the common rail injection system of the present embodiment.

FIG. 6 relates to a second embodiment of the present invention when there are two plungers 21 and the operation of the inner cam 8 at a position corresponding to the cross section AA in FIG. It is a longitudinal cross-sectional view which shows a state, (A) shows the state immediately before the suction stroke is completed and immediately before the pumping stroke is started, and (B) shows the state immediately before the pressure feeding stroke is ended and immediately before the suction stroke is started.

FIG. 7 relates to a third embodiment of the present invention in which four plungers 21 are provided, and corresponds to a section corresponding to a cross section AA in FIG. It is a longitudinal section showing the state of operation at the time of zero discharge amount when the inner cam 8 was seen from the front, and shows a state immediately before the suction stroke is completed and the pressure feed stroke is started.

FIG. 8 is a cross-sectional view of an essential part showing an example of a conventional variable discharge amount high pressure pump.

FIG. 9 is a cross-sectional view along a central axis showing a configuration of a variable discharge high pressure pump proposed by the present inventors in Japanese Patent Application No. 9-100939.

10 is a sectional view taken along the line CC in FIG.
FIG. 12 is a cross-sectional view taken along the line CC, showing the state of operation when the discharge amount is zero, when the suction stroke is completed.
(B) shows the state of the plunger, cam roller and shoe immediately after (A),
(C) shows a state in which the pressure feeding process is completed and immediately before the suction process is started.

[Description of Signs] 2 Cylinder (sliding hole) 8 Cam 11, 12, 13, 51 Low-pressure channel 21 Plunger 23 Pressure chamber

Claims (3)

[Claims] 1. A low-pressure flow path formed by a plunger fitted reciprocally in a cylinder, a cam for reciprocating the plunger in the cylinder, an inner wall surface of the cylinder and an end face of the plunger. And a pressure chamber for pressurizing the introduced low-pressure fuel by the reciprocating motion of the plunger, wherein all axial directions of the plunger are set at 30 ° to an acting direction of gravity (vertical direction). A variable discharge high pressure pump characterized by being disposed at 150 °. 2. A low-pressure flow path formed by a plunger fitted reciprocally in a cylinder, a cam for reciprocating the plunger in the cylinder, an inner wall surface of the cylinder and an end face of the plunger. And a pressure chamber for pressurizing the introduced low-pressure fuel by the reciprocating motion of the plunger, wherein the number of the plungers is four, and the axial direction of the plunger is the direction of action of gravity (vertical direction). A variable discharge high pressure pump characterized by being disposed at approximately 45 ° and approximately 135 ° with respect to the high pressure pump. 3. A low-pressure flow path formed by a plunger fitted reciprocally in a cylinder, a cam for reciprocating the plunger in the cylinder, an inner wall surface of the cylinder and an end face of the plunger. And a pressure chamber for pressurizing the introduced low-pressure fuel by the reciprocating motion of the plunger, wherein the number of the plungers is two, and the axial direction of the plunger is set in the direction of gravity (vertical direction). A variable discharge high pressure pump characterized by being disposed at about 90 ° to the pump.