JPH11230005A - High pressure supply pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent cavitation from being generated even when the discharge amount is low in a structure that a suction amount adjusting system for controlling the suction amount depending on the discharge amount of a pump is applied a pump having a pad provided between a plunger and an eccentric cam. SOLUTION: A pad 31a is provided between an eccentric cam 16 provided about a drive shaft 10 and a plunger 3a inserted into a cylinder 2a. The pad 31a is caused to abut against the eccentric cam 15 by a spring 32a. The plunger 3a is provided independently of the pad 31a and the energizing force of the spring 32a is not applied to the plunger. When a discharge amount is low, current carrying to a solenoid valve 6 is stopped and the supply of low pressure fuel to a pressure chamber 4a is interrupted, the pad 31a is separated from the plunger 3a. Thus, the volume of the pressure chamber 4a is not increased, so that the generation of cavitation can be prevented.

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 stored in a common rail (accumulation pipe) into each cylinder of a diesel engine by an electromagnetic fuel injection valve. The present invention relates to a high-pressure supply pump for pumping.

[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 accumulator pipe (common rail) communicating with each cylinder is provided, and a high-pressure supply pump supplies a required flow of high-pressure fuel to the fuel tank to maintain a constant fuel pressure in the accumulator pipe. ing. The high-pressure fuel in the accumulator pipe is injected into each cylinder by an electromagnetic fuel injection valve at a predetermined timing (for example,
JP-A-64-73166, etc.).

A high-pressure supply pump used in a common rail injection system is disclosed in JP-A-6-249133, JP-A-6-249134, etc., examples of which are shown in FIGS. In FIG. 10, a drive shaft 102 is inserted and held in a housing 101 of the high-pressure supply pump, and the drive shaft 102 has two sliding bearings (friction bearings) 103 and 104.
The eccentric part 105 is provided between them. A sliding bearing (friction bearing) 106 is provided on the outer periphery of the eccentric portion 105, and an eccentric cam 107 is provided on the outer periphery thereof.

FIG. 11 is a sectional view taken along the line BB of FIG. 10. The eccentric cam 107 has three flat portions 107 at three positions on the outer peripheral surface.
a, 107b and 107c. Eccentric cam 107
Outside these flat portions 107a, 107b, 107
cylinders 108a, 108b, 108c perpendicular to c
Are provided, and each cylinder 108a, 108b, 108c
In each plunger 109a, 109b, 109c
Are reciprocally movable. Cylinder 108a, 1
08b, 108c and plungers 109a, 10c
9b and 109c and the upper end surfaces of the pressure chambers 110a and 110c.
b, 110c are formed, and the low-pressure channels 111a, 111
Low pressure fuel is supplied from b and 111c.

[0005] Plungers 109a, 109b, 109c
And the flat portions 107a, 107b, 107 of the eccentric cam 107.
Pads 112a, 112b, and 112c are interposed between c. Also, the plungers 109a, 10
9b and 109c are integrally formed with the holding portion 1 on the outer periphery of the lower end.
13a, 113b and 113c are provided. Then, springs 115a, 115b, 115c are provided between the holding portions 113a, 113b, 113c and the outer peripheral portions of the bodies 114a, 114b, 114c forming the cylinders 108a, 108b, 108c,
Eccentric cam 1 for plungers 109a, 109b, 109c
It is biased in the 07 direction.

When the eccentric portion 105 rotates together with the drive shaft 102, the center of the eccentric cam 107 rotates about the center axis of the drive shaft 102. At this time, the flat portions 107a, 10
7b, 107c are pads 112a, 112b, 111c
The plungers 109a, 109b, and 109c are reciprocated via the, and pressurize the low-pressure fuel in the pressure chambers 110a, 110b, and 110c.

In FIG. 10, fuel in a fuel tank T is sucked into a pressure chamber 110a via a low-pressure flow path 111a during a suction step in which a plunger 109a descends. The sucked fuel is pressurized to a high pressure with the rise of the plunger 109a, and supplied to the common rail through the high-pressure channel 116. Excess high pressure fuel is relieved by the solenoid valve 117. The same applies to the pressure chambers 110b and 110c in FIG.

[0008]

As described above, in the high-pressure supply pump having the above structure, the pressure chambers 110a, 110b, 1
The low-pressure fuel sucked into 10c is a constant amount corresponding to the lift amount of the eccentric cam 107, and all the sucked low-pressure fuel is pressurized to a high pressure. Adjustment of the supply amount of high-pressure fuel to the common rail is performed by relieving excess high-pressure fuel by the solenoid valve 117. For this reason, there are disadvantages such as deterioration of fuel efficiency of the engine to which the high-pressure supply pump having the above-mentioned configuration is applied, and excessive rise in fuel temperature.

On the other hand, the present inventors have disclosed in Japanese Patent Application No. 8-1956.
In No. 53, etc., an electromagnetic valve for controlling the flow rate of low-pressure fuel sucked into the pressure chamber from the low-pressure flow path, and opening and closing between the low-pressure flow path and the pressure chamber, between the start of pressurization and the end of pressure feeding. A high-pressure supply pump of the suction amount metering type provided with a valve member for shutting off the pressure is proposed. This high-pressure supply pump can control the flow rate of the high-pressure fuel supplied to the common rail by controlling the flow rate of the low-pressure fuel drawn into the pressure chamber from the low-pressure flow path. Therefore, an electromagnetic valve for relieving excess high-pressure fuel is provided. It is possible to suppress the deterioration of the fuel efficiency without the need for the fuel consumption.

Therefore, this configuration is applied to the high-pressure supply pump shown in FIGS.
Instead of 7, it is conceivable to provide an electromagnetic valve that controls the flow rate of the low-pressure fuel and a valve member that opens and closes between the low-pressure flow path and the pressure chamber. However, in the suction amount metering method, the suction amount into the pressure chamber fluctuates according to the discharge amount.
When applied to the high-pressure supply pumps 0 and 11, the following problems occur when the discharge amount is small. That is, even after the supply of the low-pressure fuel to the pressure chambers 110a, 110b, 110c is interrupted by the urging forces of the springs 115a, 115b, 115c, the plungers 109a, 109b,
9c descends, and the volumes of the pressure chambers 110a, 110b, 110c increase. For this reason, the pressure chamber 110
Air bubbles (cavitation) may be generated in the fuels a, 110b, and 110c, and the durability performance may be deteriorated.

Further, the springs 115a, 115b, 1
Since the eccentric cam 107 is held at a predetermined position by 15c, if the springs 115a, 115b and 115c are abolished for the purpose of preventing cavitation, another problem that the positional relationship of the eccentric cam 107 is deviated occurs. I do.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent the volume of the pressure chamber from being increased by the urging force of the spring after the supply of fuel is stopped when the discharge amount of the high-pressure supply pump is small, and to prevent the occurrence of cavitation. An object of the present invention is to provide a high-pressure supply pump capable of preventing the occurrence of a durable performance.

[0013]

According to a first aspect of the present invention, a high-pressure supply pump includes a cylinder disposed around a drive shaft, a plunger inserted reciprocally in the cylinder, An eccentric cam that is eccentrically rotated relative to a drive shaft and reciprocates the plunger in the cylinder; and an inner wall surface of the cylinder and an end face of the plunger, which supplies the low-pressure fuel introduced from the low-pressure flow path to the plunger. A pressure chamber that pressurizes by reciprocating motion of the pressure chamber; an electromagnetic valve that controls the amount of low-pressure fuel flowing into the pressure chamber; A valve member for shutting off between the pressure chamber and the low-pressure channel until the end of the pressure feeding. A pad interposed between the eccentric cam and the plunger and sliding back and forth with respect to the eccentric cam, a spring for biasing the pad in the eccentric cam direction are provided, and the plunger is provided independently of the pad. It is a thing.

According to the above construction, the plunger is provided independently of the pad so that the biasing force of the spring does not act on the plunger. After the supply of the low-pressure fuel is cut off, the pad and the plunger separate. Therefore, the volume of the pressure chamber does not increase after the supply of fuel is stopped, and the occurrence of cavitation can be prevented and the durability performance can be improved.

According to the second aspect of the present invention, the high-pressure supply pump includes a cylinder disposed around a drive shaft, a plunger inserted reciprocally in the cylinder, and the plunger rotating with the drive shaft. A cam that reciprocates in the cylinder, a pressure chamber formed by an inner wall surface of the cylinder and an end face of the plunger, and pressurizes low-pressure fuel introduced from a low-pressure flow path by reciprocation of the plunger; An electromagnetic valve for controlling the amount of low-pressure fuel flowing into the chamber; and a pressure chamber and the low-pressure flow path from the start of pressurization of the low-pressure fuel flowing into the pressure chamber to the end of pressurization of the pressurized fuel to the high-pressure flow path. And a valve member for shutting off between the valve member.
A slider interposed between the cam and the plunger and reciprocating in accordance with the rotation of the cam, and a spring for urging the slider in the cam direction are provided. It is provided independently of the child.

According to the above construction, the plunger is provided independently of the slider, so that the biasing force of the spring does not act on the plunger. After the supply of the low-pressure fuel to the chamber is cut off, the slider and the plunger separate. Therefore, even with the above-described configuration, the same effect of improving the durability performance by preventing the volume of the pressure chamber from increasing after the supply of fuel is stopped, and preventing cavitation from occurring can be obtained.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example in which the high-pressure supply pump of the present invention is applied to a common rail injection system for a diesel engine will be described. In the system diagram of FIG.
The engine E is provided with a plurality of electromagnetic fuel injection valves I corresponding to the combustion chambers of each cylinder, and these electromagnetic fuel injection valves I are connected to a common high-pressure accumulator pipe, a so-called common rail R, for each cylinder. 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 supply pipe R1, which is a high-pressure flow path, and the discharge valve B
Is connected to the high-pressure supply pump P of the present invention. The injection of fuel from the electromagnetic fuel injection valve I to each combustion chamber of the engine E is controlled by the electronic control unit ECU.

The high-pressure supply pump P pressurizes 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.
The discharge amount of the high-pressure supply pump P is determined and a signal is output to the discharge control device P2 such that the signal from the pressure sensor S1 has an optimum value set in advance according to the load and the rotation speed.
Further, information on the number of revolutions and load is input to the electronic control unit ECU from, for example, the engine speed sensor S2 and the load sensor S3. Is determined, and a control signal is output to the electromagnetic fuel injection valve I.

Next, the details of the high-pressure supply pump P will be described with reference to FIG. In the figure, a high-pressure supply pump P
Has pump housings 1a and 1b, and a drive shaft 10 serving as a drive shaft is rotatably supported by two sliding bearings (friction bearings) 11 and 12 provided on the pump housings 1a and 1b, respectively. The drive shaft 10 is rotationally driven by the engine E (see FIG. 2) in synchronization with a half rotation of the engine. The drive shaft 10 has an eccentric portion 13 between the two slide bearings 11 and 12, and the eccentric portion 13
The drive shaft 10 is eccentric with respect to the center axis s by a distance u. A sliding bearing (friction bearing) 14 is provided on the outer periphery of the eccentric portion 13, and is rotatable with respect to an eccentric cam 15 disposed on the outer periphery thereof.

FIG. 3 is a sectional view taken along line AA of FIG. 1. The eccentric cam 15 has three flat portions 15a, 1
It has a substantially polygonal shape having 5b and 15c. 3
The cylinders 2a, 2b, 2c are respectively formed in the bodies 21a, 21b, 21c disposed outside the two flat portions 15a, 15b, 15c, respectively.
Plungers 3a, 3b, 3c are slidably disposed on 2b, 2c. Three flat portions 15a, 15b, 1
5c is formed such that the angle α between any two is 60 °, and the three cylinders 2a, 2b, 2c are arranged such that their central axes are at an angular interval of 120 °. Also, the three flat portions 15a, 15b, 15c
Each is perpendicular to the center axis of the cylinder 2a, 2b, 2c.

When the drive shaft 10 rotates, the center t of the eccentric cam 15 is moved to the drive shaft 10.
Rotate along a circular path with a radius u centered on the central axis s. Then, each flat part 15a, 15 of the eccentric cam 15
b, 15c operate in parallel along a circular path, and the plungers 3a, 3b, 3c are cylinders 2a, 2b, 2c
Reciprocatingly slides inside (FIGS. 3 to 5). Along with this, the pressure chambers 4a, 4a provided to face the plungers 3a, 3b, 3c
The low pressure fuel in b, 4c is pressurized to high pressure.

The supply path of the low-pressure fuel into the pressure chambers 4a, 4b, 4c will be described with reference to FIG. In the figure, an electromagnetic valve 6 is provided at the lower end of the pump housing 1b, and a fuel reservoir 16 is provided therearound. Fuel tank T
The fuel inside is pressurized to about 10 atm by the feed pump P1 and sent out to the fuel reservoir 16 through the low pressure flow path L. The solenoid valve 6 is fixed to the pump housing 1b by inserting a bolt (not shown) through a flange 6b provided on the outer periphery of the housing 6a. The solenoid valve 6 corresponds to the discharge control device P2 in FIG.

As shown in FIG. 6, the solenoid valve 6 has a housing 6a containing a coil 61 and a valve body 6c fitted and fixed in the left end thereof. A valve 62 is provided in a cylinder 62 provided in the valve body 6c. The body 63 is slidably held. An annular flow path 64 is formed around the left end of the valve body 63. The flow path 64 communicates with the fuel reservoir 16 and the low-pressure flow path 17 shown in FIG. An armature 67 is press-fitted and fixed to the right end of the valve body 63, and the armature 67 faces the stator 68 at a constant interval. Outside the stator 68, the coil 61
And a spring chamber 6d provided inside the stator 68.
A spring 69 is disposed inside the armature 6.
7 is urged to the left in the figure.

A substantially conical seat surface 6e is formed at the open end of the flow passage 66, and in a state shown in FIG. The passages 64 and 66 are closed. When the coil 61 is energized, the armature 67 is attracted, and the tip of the valve body 63 integral with the armature 67 is separated from the seat surface 6e, and
Open between 4, 66. 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.

As shown in FIG. 1, the flow path 66 communicates with an annular low-pressure flow path 18 provided on the outer periphery of the right end of the pump housing 1a through a low-pressure flow path 17 provided below the pump housing 1b. The annular low pressure passage 18 communicates with a low pressure passage 19 provided above the pump housing 1b, and further communicates with the pressure chamber 4a above the plunger 3a through passages 24 and 25.

FIG. 7 is an enlarged view of the plunger 3a and its peripheral portion. A plunger 3 is provided in the upper end of the body 21a.
A plate 5a as a valve member is disposed above the pressure chamber 4a formed by the upper end surface of the cylinder a and the inner wall surface of the cylinder 2a. A cover 2 is provided on the upper part of the pump housing 1b.
2 is fixed by a bolt (not shown), and the upper surface of the body 21 a is in close contact with the lower surface of the flow path forming member 23 provided in the cover body 22. The channels 24 and 25 are formed in the cover body 22 and the channel forming member 23, respectively.

The plate 5a functions as a check valve and has a plurality of holes 51a penetrating the plate surface. In FIG. 1, when the valve body 63 of the solenoid valve 6 is opened, the fuel in the fuel reservoir 16 flows from the low-pressure channels 17, 18, 19 through the holes 51a provided in the channels 24, 25 and the plate 5a.
It flows into the pressure chamber 4a. When the pressure feed of the plunger 3a starts, the pressure of the pressure chamber 4a increases, and the plate 5a
Is in close contact with the lower surface of the flow path forming member 23. Thus, the communication between the flow path 25 and the pressure chamber 4a is cut off. Thereafter, when the pressure further rises to a predetermined pressure as the volume of the pressure chamber 4a decreases, the ball 2 configured as a check valve
9 is opened, and the high-pressure fuel in the pressure chamber 4a
It is supplied to the common rail R through 6, 27 and 28. Here, the ball 29 corresponds to the discharge valve B in FIG. That is, in the present embodiment, three discharge valves B are provided.

A pad 31a is interposed between the flat portion 15a of the eccentric cam 15 and the plunger 3a. Pad 3
1a has a cylindrical portion extending above the outer peripheral edge along the inner peripheral surface of the housing 1b, and is slidably supported in the housing 1b. A spring 3 is provided between the pad 31a and a step provided on the outer periphery of the body 21a.
2a is arranged, and the pad 31a is brought into contact with the flat portion 15a of the eccentric cam 15 by the urging force. Thus, when the eccentric cam 15 operates eccentrically, the pad 31a
Slides back and forth with respect to the flat portion 15.

Although the description has been made above centering around the pressure chamber 4a, the periphery of the pressure chambers 4b and 4c has the same configuration. That is, as shown in FIG. 3, pads 31b and 31c are interposed between the flat portions 15b and 15c of the eccentric cam 15 and the plungers 3b and 3c, respectively, and the flat portions 15b and 31c are urged by the springs 32b and 32c. Fifteen
c. Each of the plungers 3a, 3b, 3c is provided independently of the pads 31a, 31b, 31c, and does not act on the urging force of the springs 32a, 32b, 32c. The pressure of the common rail R varies depending on the operation state of the engine E, but is about 200 to 1600 atm (about 20 to 160 MPa).

Next, the operation of the high-pressure supply pump according to the present embodiment will be described mainly with reference to FIGS. FIG. 8A shows a state in which the lift amount of the plunger 3a is maximum, and the volume of the pressure chamber 4a is the smallest. Here, when the coil 61 of the electromagnetic valve 6 in FIG. 1 is energized, the valve body 63 opens, and the fuel reservoir 16 and the low-pressure flow path 17 communicate. Next, the drive shaft 10
When the eccentric cam 15 starts lowering due to the rotation of, the pad 31a also lowers by the urging force of the spring 32a. At that time, the low pressure fuel of about 10 atm in the fuel reservoir 16 is supplied to the flow path in the solenoid valve 6 and the low pressure flow paths 17, 18, 19, 24, 2
5, through the hole 51a provided in the plate 5a, the pressure chamber 4
a, and lowers the plunger 3a (FIG. 8).
(B)).

When the energization of the coil 61 of the solenoid valve 6 is cut off, the valve body 63 closes and the supply of the low-pressure fuel to the pressure chamber 4a stops. After that, the eccentric cam 15 is lowered, and the pad 31a is also lowered by the urging force of the spring 32a. Thereby, the plunger 3a and the pad 31a are separated. Therefore, it is possible to prevent cavitation from occurring in the pressure chamber 4a (FIG. 8C).

When the eccentric cam 15 starts to move upward by the rotation of the drive shaft 10, the pad 31a also rises against the urging force of the spring 32a, and the pad 31a contacts the plunger 3a. After the contact between the pad 31a and the plunger 3a, the pressure in the pressure chamber 4a increases, and the plate 5a as a check valve comes into close contact with the lower surface of the flow path forming member 23, and the low pressure flow path 25 and the pressure chamber 4a Communication is interrupted.
When the pressure in the pressure chamber 4a reaches a predetermined pressure, the ball 29, which is a discharge valve, opens, and high-pressure fuel is supplied to the common rail R (FIG. 8D).

FIG. 9 shows a second embodiment of the present invention.
In FIG. 9, a cam chamber 73 is formed at a lower end of a pump housing 72 of a high-pressure supply pump 71. A drive shaft 74 is inserted through the cam chamber 73 as a drive shaft that is driven to rotate in synchronization with a half rotation of the engine. A cam 75 is formed in the drive shaft 74. The cam 75 makes a three-degree upward stroke per rotation of the drive shaft 74.

A cylinder member 77 having a cylinder 76 formed therein is attached to an upper portion of the pump housing 72, and a plunger 78 is fitted in the cylinder 76 in a reciprocating and slidable manner. Plunger 78
Unlike a conventional column-type injection pump, a cylindrical plunger having a notch formed on the outer peripheral surface thereof has a cylindrical shape without any leads. A pressure chamber 79 is formed by the upper end surface of the plunger 78 and the inner wall surface of the cylinder 76.
An ejection hole 80 communicating with the nozzle 9 is formed.

The solenoid valve 6 similar to that used in the first embodiment is fixed to the cylinder member 77 by bolts (not shown). The fuel reservoir 82 formed around the solenoid valve 6 has a feed pump P
The low-pressure fuel which has been sent to 1 and is pressurized to about 10 atm is supplied through a low-pressure channel 81.

A discharge valve 83 is attached to the cylinder member 77, and the discharge valve 83 communicates with a pressure chamber 79 through a discharge hole 80. The fuel pressurized in the pressure chamber 79 pushes the valve body 84 of the discharge valve 83 open against the urging force of the return spring 85, and the high-pressure fuel pressurized by this is fed into the common rail.

Below the plunger 78, a slider 86 is slidably disposed in a cylinder 88 formed in the pump housing 72. The slider 86 is provided with a spring 8 disposed between the slider 86 and a step provided on the outer periphery of the cylinder member 77.
The cam roller 89 urged downward by 7 and held in the cylindrical portion of the slider 86 is in sliding contact with the cam 75. Thus, when the cam 75 is rotated by the rotation of the drive shaft 74, the cam roller 89 and the slider 86 are driven to reciprocate accordingly. The plunger 78 is provided independently of the slider 86, and does not receive the urging force of the spring 87.

A check valve 91 serving as a valve member is disposed above the cylinder member 77 between the low-pressure flow path 90 leading to the fuel reservoir 82 and the pressure chamber 79, and is fixed in the cylinder member 77 by a screw 92. I have. The solenoid valve 6 controls the communication between the fuel reservoir 82 and the low-pressure passage 90 and the cutoff.
When the coil 61 is energized, the valve 63 opens, and low-pressure fuel flows into the pressure chamber 79 from the fuel reservoir 82 through the low-pressure flow path 90 and the check valve 91.

The check valve 91 includes a flow path 94 vertically penetrating the housing 93 and a valve element 95 for opening and closing the flow path 94.
Having. The flow path 94 expands in the middle in the direction of the pressure chamber 79 (downward in the figure) to form a conical seat surface 96.
Is the spring 9 held in the spring stopper 97
8, and is seated on the seat surface 96. As described above, the check valve 91 is closed in the illustrated normal state. When the solenoid valve 6 is opened and low-pressure fuel flows from the fuel reservoir 82, the check valve 91 is opened by the fuel pressure. . When the valve is opened, the low-pressure fuel flows into the pressure chamber 79 through the flow path 90, the flow path 99 provided in the housing 93, and the flow path 94.

Here, the operation of the high-pressure supply pump according to the present embodiment will be described. When the coil 61 of the electromagnetic valve 6 is energized, the valve body 63 is opened, and the fuel reservoir 82 and the low-pressure flow path 90 communicate. In the illustrated state, the plunger 7
8, the lift amount is maximum, and when the cam 75 is rotated by the rotation of the drive shaft 7 from this state, the slider 86 is biased by the spring 87 to rotate the cam roller 89.
Lowers along the cam surface of the cam 75. At this time, low-pressure fuel pressurized to about 10 atm flows into the pressure chamber 79a and pushes down the plunger 78.

Thereafter, when the energization of the coil 61 of the solenoid valve 6 is cut off, the communication between the fuel reservoir 82 and the low-pressure passage 90 is cut off, and the supply of the low-pressure fuel to the pressure chamber 79 is stopped.
Thereafter, the slider 86 descends, but the plunger 78 does not descend, and the slider 86 and the plunger 78 separate. Therefore, cavitation does not occur in the pressure chamber 79a.

Further, when the cam 75 enters the pressure feeding stroke, the slider 86 rises against the urging force of the spring 87, and the lower end surface of the plunger 78 contacts the slider 86. Thereafter, the pressurization of the fuel in the pressure chamber 79 starts, and the discharge valve 83
, A high-pressure fuel of about 200 to 1600 atm (about 20 to 160 MPa) is supplied to the common rail R.

As described above, according to the present invention, in a configuration in which a pad or a slider is interposed between the plunger and the cam, the plunger is provided independently of the pad or the slider, and the biasing force of the spring acts on the plunger. I decided not to
Cavitation can be prevented from occurring and durability performance can be improved. Also, since a spring is arranged,
There is no danger that the positional relationship between the eccentric cams will be out of order, and a highly reliable high-pressure supply pump can be realized.

[Brief description of the drawings]

FIG. 1 is an overall sectional view of a high-pressure supply pump showing a first embodiment of the present invention.

FIG. 2 is an overall configuration diagram of a fuel injection system including a high-pressure supply pump according to the first embodiment.

FIG. 3 is a diagram for explaining the operation of an eccentric cam and a plunger.

FIG. 4 is a view for explaining the operation of an eccentric cam and a plunger.

FIG. 5 is a view for explaining the operation of an eccentric cam and a plunger.

FIG. 6 is an enlarged sectional view of a solenoid valve.

FIG. 7 is an enlarged cross-sectional view of the upper part of FIG.

FIGS. 8A to 8D are diagrams for explaining the operation of the first embodiment.

FIG. 9 is an overall sectional view of a high-pressure supply pump according to a second embodiment of the present invention.

FIG. 10 is an overall sectional view of a conventional high-pressure supply pump.

FIG. 11 is a sectional view taken along line BB of FIG. 10;

[Explanation of symbols]

 P High pressure supply pump 1a, 1b Pump housing 10 Drive shaft (drive shaft) 15 Eccentric cam 16 Fuel pool 17, 18, 19, 24, 25 Low pressure channel 26, 27, 28 High pressure channel 2a, 2b, 2c Cylinder 3a, 3b, 3c Plunger 31a, 31b, 31c Pad 32a, 32b, 32c Spring 4a, 4b, 4c Pressure chamber 5a, 5b, 5c Check valve (valve member) 6 Solenoid valve 74 Drive shaft (drive shaft) 75 Cam 76 Cylinder 78 Plunger 79 Pressure chamber 86 Slider 87 Spring 89 Cam roller 91 Check valve (valve member)

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Showa Kojima 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Inside DENSO Corporation

Claims (2)

[Claims] 1. A cylinder disposed around a drive shaft, a plunger fitted reciprocally in the cylinder,
An eccentric cam that is eccentrically rotated relative to the drive shaft and reciprocates the plunger in the cylinder, and formed by an inner wall surface of the cylinder and an end surface of the plunger, and supplies the low-pressure fuel introduced from the low-pressure flow path A pressure chamber for pressurizing by the reciprocating motion of the plunger; an electromagnetic valve for controlling the amount of low-pressure fuel flowing into the pressure chamber; and a high-pressure flow path for the pressurized fuel from the start of pressurization of the low-pressure fuel flowing into the pressure chamber. A high-pressure supply pump comprising a valve member for shutting off the pressure chamber and the low-pressure flow path until the end of the pressure feeding of the eccentric cam, the pad interposed between the eccentric cam and the plunger and slidably moved relative to the eccentric cam. And a spring for urging the pad in the eccentric cam direction, and the plunger is provided independently of the pad, so that the urging force of the spring is applied to the plunger. High-pressure supply pump, characterized in that to avoid use. 2. A cylinder disposed around a drive shaft, and a plunger inserted reciprocally in the cylinder.
A cam that rotates with the drive shaft to reciprocate the plunger in the cylinder; and a reciprocating motion of the plunger formed by an inner wall surface of the cylinder and an end face of the plunger, the low-pressure fuel introduced from the low-pressure flow path. A pressure chamber pressurized by the pressure chamber, an electromagnetic valve for controlling the amount of the low-pressure fuel flowing into the pressure chamber, and a time when the pressurization of the low-pressure fuel flowing into the pressure chamber is started from the start of the pressurization of the pressurized fuel to the high-pressure flow path. In a high-pressure supply pump comprising a valve member that shuts off between the pressure chamber and the low-pressure flow path, a slider that is interposed between the cam and the plunger and reciprocates according to rotation of the cam, A spring for biasing the slider in the cam direction is provided, and the plunger is provided independently of the slider so that the biasing force of the spring does not act on the plunger. High-pressure supply pump, characterized in that the.