JPH1122594A - Fuel pressurizng pump for fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel pressurizing pump capable of accurately controlling the fuel discharge flow with a simple structure, capable of being manufactured at a low cost, reducing the operating frequency of parts, and increasing the durability of the parts. SOLUTION: A piston hole 27 is formed along the axial direction on the end face of a plunger 8 on the side of a pump chamber 17. The first side path 28 communicating the bottom side position of the piston hole 27 and an intake passage 2 and the second side path 29 communicating the opening side position of the piston hole 27 and the pump chamber 17 are formed on the plunger 8. An operation piston 33 capable of opening or closing the second side path 29 is slidably inserted into the piston hole 27. The rotation of a stepping motor 34 is converted into a linear motion by a screw mechanism to operate the longitudinal position of the operation piston 33. When the longitudinal position of the operation piston 33 is controlled, the pressurization start timing by the plunger 8 is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel pressurizing pump for a fuel injection device capable of variably controlling a discharge flow rate according to an operating condition of an engine.

[0002]

2. Description of the Related Art A plunger type pump has been conventionally used as a fuel pressurizing pump used in a fuel injection device of an automobile engine. In this fuel pressurizing pump, a plunger is pushed by a rotating cam that rotates integrally with a drive shaft to advance and retreat in a cylinder, and performs suction and discharge of fuel in a pump chamber formed between the cylinder and the plunger. Has become.

[0003] As this kind of fuel pressurizing pump,
2. Description of the Related Art Conventionally, a device provided with a flow rate control mechanism for variably controlling a fuel discharge flow rate in accordance with an operation state of an engine has been proposed.

[0004] This pump has a schematic configuration in which a drain passage is branched and formed in a discharge passage communicating with a pump chamber, and a valve body controlled to be opened and closed by a solenoid is interposed in the drain passage. At the time of a discharge process in which the plunger is retracted into the cylinder, the valve opening time (drain time of fuel) of the valve body is adjusted by controlling a solenoid, thereby controlling the flow rate of fuel discharged from the discharge passage. I have.

Incidentally, this similar technique is disclosed in, for example,
No. 31,179 and No. 8-303325.

[0006]

However, in the case of the above-mentioned conventional fuel pressurizing pump, the opening and closing of a valve interposed in the drain passage is controlled by a solenoid every time the plunger is operated. Since the control of the solenoid when the motor is in the high rotation range becomes fine, the control of the solenoid becomes complicated, and very high responsiveness of the solenoid is required. For this reason, in the above-described conventional pump, the manufacturing cost is increased, and the durability of parts is apt to be reduced.

Accordingly, the present invention provides a fuel pressurizing pump for a fuel injection device which can be manufactured at a low cost and has a high component durability by enabling a fuel discharge flow rate to be accurately controlled by a relatively simple structure. It is something to offer.

[0008]

As a means for solving the above-mentioned problems, according to the invention of claim 1, a plunger responsive to the rotation of a drive shaft is accommodated in a cylinder so as to be able to advance and retreat, and the cylinder and the plunger are connected to each other. In a fuel pressurizing pump of a fuel injection device in which a suction passage and a discharge passage are connected to a pump chamber formed therebetween through check valves, respectively, the pump chamber communicates with the suction passage, and the plunger moves forward and backward. A bypass passage opened / closed by the operation, an operation piston for operating the opening / closing position of the bypass passage by the plunger, and an actuator for moving the operation piston forward / backward according to the operating condition of the engine are provided. If the bypass passage is opened during the discharge stroke in which the plunger is retracted into the cylinder, the fuel in the pump chamber is returned to the suction passage through the bypass passage without being pressurized. Therefore, when the opening / closing position of the bypass passage by the plunger is operated, the pressurization start timing or pressurization end timing by the plunger changes, and as a result, the discharge flow rate per one stroke of the plunger changes.

According to a second aspect of the present invention, in the first aspect of the present invention, a piston hole is formed along an axial direction on an end face of the plunger on the pump chamber side, and further, the plunger is closer to the bottom of the piston hole. The first that communicates the position and the suction passage
A side path and a second side path communicating the pump chamber with the position near the opening of the piston hole are formed, and an operation piston capable of opening and closing the second side path can slide in the piston hole from the pump chamber side. The closing timing of the second bypass at the time of the retreat operation of the plunger is controlled by the position operation of the operating piston. By controlling the closing timing of the second bypass, the pressure start timing by the plunger is controlled, and as a result, the discharge flow rate per one stroke of the plunger is controlled.

According to a third aspect of the present invention, in the first aspect of the present invention, a piston hole is formed along the axial direction on an end face of the plunger on the pump chamber side, and further, the plunger is closer to the bottom of the piston hole. The first that communicates the position and the suction passage
A side path and a second side path communicating the pump chamber with the position near the opening of the piston hole are formed, and the outer peripheral surface of the operating piston has a width capable of communicating the first side path and the second side path. An annular groove is formed, and the operating piston is slidably fitted in the piston hole, and the first bypass and the second side passage passing through the annular groove when the plunger is retracted by a position operation of the operating piston. The communication timing of the bypass is controlled. By controlling the communication timing between the first side path and the second side path, the pressurization termination timing by the plunger is controlled, and as a result, the discharge flow rate per one stroke of the plunger is controlled.

According to a fourth aspect of the present invention, there is provided the actuator according to any one of the first to third aspects, wherein the actuator includes a stepping motor, and a screw mechanism for converting a rotational motion of the stepping motor into a linear motion. did.

According to a fifth aspect of the present invention, the actuator according to any one of the first to third aspects is constituted by a solenoid.

According to a sixth aspect of the present invention, the actuator according to any one of the first to third aspects is constituted by a piezoelectric element.

[0014]

Next, an embodiment of the present invention will be described with reference to the drawings.

First, a first embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG.

1 and 2, reference numeral 1 denotes a fuel pressurizing pump according to the present invention, and the fuel pressurizing pump 1 is used in a fuel injection device of an automobile engine. That is,
A supply pump 3 driven by a motor is connected to a suction passage 2 of the fuel pressurizing pump 1 via a low-pressure regulator 4.
An injector 6 of a fuel injection device is connected to the discharge passage 5. The fuel sent from the fuel tank 7 via the supply pump 3 is pressurized to a set high pressure by the pump 1 according to the present invention and then supplied to the injector 6. It is supposed to.

The fuel pressurizing pump 1 has a single plunger 8 which moves forward and backward to perform a pump action, and the plunger 8
A drive shaft 9 that is arranged along a direction perpendicular to the forward and backward directions of the drive shaft and rotates by receiving the power of the engine, and a rotary cam that is provided integrally with the drive shaft 9 and transmits an operating force to the plunger 8 through an outer peripheral surface thereof. The rotation of the drive shaft 9 is converted into an advance / retreat operation of the plunger 8 via the rotary cam 10, and the intake and discharge of the fuel are performed by the advance / retreat operation of the plunger 8. The number of cam ridges (four in this embodiment) corresponding to the number of cylinders of the engine is formed on the outer peripheral surface of the rotary cam 10.

A pump body 11 of the fuel pressurizing pump 1 is formed in a substantially cylindrical shape. A cylinder 13 is fitted to one end of a shaft hole 12 and a blind lid 14 is fitted to the other end. Have been. At a position intersecting with the shaft hole 12 on the other end side of the pump body 11, a rotary cam 10 integrally attached to the drive shaft 9 is rotatably supported via a bearing 14.

A holder 15 to be described later is press-fitted and fixed to an end of the cylinder 13 opposite to the rotary cam 10 side, and the plunger 8 slides in a cylinder hole 16 whose bottom is closed by the holder 15 in this manner. It is housed movably. The space between the bottom of the cylinder hole 16 and the plunger 8 is a pump chamber 17 and the plunger 8
The volume of the pump chamber 17 is increased or decreased by the forward / backward movement of the pump chamber 17. The cylinder 13 and the pump body 11 are provided with a supply / discharge hole 18 which is always in communication with the pump chamber 17.
The suction passage 2 and the discharge passage 5 are connected via the discharge check valve 9 and the discharge check valve 20, respectively. The supply and discharge of fuel in the pump chamber 17 are basically performed through the supply and discharge passage 18.

The shaft hole 12 of the pump body 11 is formed such that the diameter of the rotary cam 10 side from the cylinder fitting portion is increased in a stepped manner, and the enlarged diameter portion is a lifter chamber 21. A bush 22 is pressed into the peripheral wall of the lifter chamber 21, and a bottomed cylindrical lifter 23 is slidably fitted in the bush 22. The lifter 23 is configured such that the tip of the plunger 8 contacts the center of the inner surface of the bottom wall, and the outer peripheral surface of the rotary cam 10 directly contacts the outer surface of the bottom wall. Also, at the tip of the plunger 8,
An annular spring seat 2 via a snap ring 24
A spring 26 for urging the plunger 8 toward the rotary cam 10 is interposed between the spring seat 25 and the upper wall of the lifter chamber 21.

In the center of the end face of the plunger 8 on the pump chamber 17 side, a piston hole 27 having a set depth is formed along the axial direction of the plunger 8. A first bypass 28 which communicates the offset position with the outer peripheral surface of the plunger 8;
A plurality of second side paths 29 each communicating the position near the opening of the opening 7 and the outer peripheral surface of the plunger 8 are formed. The pump body 11 and the cylinder 13 are formed with a bypass hole 30 that communicates with the substantially central portion of the cylinder hole 16 in the axial direction and bypasses the suction check valve 19 with the suction passage 2. An annular groove 31 having a set width that is always in communication with the bypass hole 30 is formed at a position where the first bypass 28 opens. Therefore,
The position of the piston hole 27 near the bottom is always the suction passage 2 through the first bypass 28, the annular groove 31, and the bypass hole 30.
Is in communication with The outer circumference of the distal end portion of the plunger 8 where the second side passage 29 opens is reduced in diameter, and the reduced diameter portion 32 allows the second side passage 29 to move through the pump chamber 17 irrespective of the plunger 8 advance / retreat position. To be constantly conducted. Note that, in this embodiment, the bypass hole 30,
The bypass passage in the present invention is constituted by the annular groove 31, the first side passage 28, the piston hole 27, the second side passage 29, and the like.

A rod-shaped operating piston 33 is slidably fitted into the piston hole 27 of the plunger 8 from the pump chamber 17 side. The operation piston 33 relatively slides in the piston hole 27 by the reciprocating operation of the plunger 8, and at the time of the sliding, opens and closes the second bypass 29 at the tip end. The opening / closing timing of the second bypass 29 during the movement of the plunger 8 is determined by the axial position of the operating piston 33. The axial position of the operating piston 33 is determined by the stepping motor attached to the pump body 11. 34.

That is, the base of the operating piston 33 is coupled to the shaft 34a of the stepping motor 34 in a state where the relative movement in the axial direction is allowed and the rotation is stopped. A male screw member 35 is caulked and fixed to this, and the male screw member 35 is screwed into a screw hole 36 formed in the holder 15. Therefore, when the shaft 34a of the stepping motor 34 rotates, the operating piston 33 rotates integrally with the shaft 34a, and the rotation is converted into the axial displacement of the operating piston 33 by the screw mechanism of the male screw member 35 and the screw hole 36. Then, the operation piston 33 is displaced in the axial direction by an amount corresponding to the rotation speed of the stepping motor 34. And the stepping motor 3
The rotation of No. 4 is controlled by a controller (not shown) according to the operating condition of the engine.

A seal ring 37 is mounted on the outer peripheral surface of the plunger 8 closer to the rotary cam 10 than the annular groove 31, and the fuel in the annular groove 31 further passes through the sliding gap between the plunger 8 and the cylinder 13. The seal ring 37 reliably prevents leakage to the lifter chamber 21 side.

In the above configuration, when the drive shaft 9 rotates with the start of the engine, the outer peripheral surface of the rotary cam 10 comes into rotational contact with the lifter 23, and the plunger 8
, The operation of the rotary cam 10 is received through the cylinder 13 to advance and retreat in the cylinder 13.

At this time, when the plunger 8 is displaced in a direction to protrude from the inside of the cylinder 13, the inside of the pump chamber 17 becomes a negative pressure, the suction check valve 19 is opened, and the fuel sent from the supply pump 3 is supplied to the pump chamber 17. It is sucked in. Thereafter, when the plunger 8 is pressed by the rotating cam 10 and retreats into the cylinder 13, the fuel in the pump chamber 17 is pressurized to open the discharge check valve 20, and the pressurized fuel flows through the discharge passage 5. The fuel is supplied to the injector 6 of the fuel injection device.

Here, in the above-described stroke in which the plunger 8 retreats into the cylinder 13, the fuel is not always discharged throughout the stroke, but the operation piston 3 is moved.
The discharge of the fuel in the initial stage of the retreat of the plunger 8 is appropriately cut in accordance with the set position of 3. Hereinafter, the operation at this point will be described in detail.

Now, if the plunger 8 protrudes from the cylinder 13 to the maximum, as shown in FIG.
If the second bypass 29 is open, the pump chamber 17
Communicates with the suction passage 2 via a bypass passage including a second side passage 29, a piston hole 27, a first side passage 28, a bypass hole 30, and the like.

When the plunger 8 retreats from this state, the fuel in the pump chamber 17 flows into the suction passage 2 via the bypass passage, and the fuel is not discharged from the pump chamber 17 to the discharge passage 5. This state is shown in FIG.
(B), as shown in FIG. 3 (c), the second bypass 29 is closed by the retreat of the plunger 8 at the distal end of the operating piston 33, and then the bypass 29 is closed. The pressurization of the fuel in the pump chamber 17 is started from the time of closing, and the fuel is discharged to the discharge passage 5 by opening the discharge check valve 20.

Therefore, in the retreat stroke of the plunger 8, as shown in FIG. 4, the discharge is not performed during the predetermined stroke at the initial stage of the retreat of the plunger 8, and the total discharge amount per one stroke of the plunger 8 is as shown in FIG. This is equivalent to the area of the shaded portion.

The stroke range in which discharge is not performed in the retreat stroke of the plunger 8 is changed in accordance with the advance / retreat position of the operating piston 33 as described above. This is performed by a stepping motor 34 and a screw mechanism (35, 36) for converting the rotation into a linear motion. At this time, since the stepping motor 34 is controlled according to the operating condition of the engine, the flow rate of the fuel discharged into the discharge passage 5 also depends on the operating condition of the engine.

The operating range of the operating piston 33 is as follows.
Regardless of the position of the plunger 8, the position extends from a position where the second bypass 29 is always closed to a position where the second bypass 29 is always opened. When it is desired to rapidly obtain a large discharge flow rate such as when starting the engine, the operating piston 33 is operated at a position where the second bypass 29 is always closed, and when the discharge by the pump 1 is to be stopped. The operation piston 33 is operated to a position where the second bypass 29 is always opened.

As described above, the fuel pressurizing pump 1 does not control the drain time from the pump chamber 17 every time the plunger 8 is actuated. Instead, the open / close position of the bypass passage by the plunger 8 is controlled by the operating piston 33. Since the control is performed by the position operation, the control of the discharge flow rate is simplified, and the durability of the components is improved because the frequency of component operations during the control is low.

The fuel pressurizing pump 1 of this embodiment
Describes a stepping motor 34 and a screw mechanism as actuators for operating the operating piston 33 (35, 3).
6) Since it is used, fine control with high accuracy can be performed by the stepping motor 34, and the influence of the reaction force from the operating piston 33 can be reduced by the screw mechanism (35, 36). Therefore, it is possible to accurately control the advance / retreat position of the operation piston 33 from these facts.

Further, in this pump 1, there is no need to process the passage or the like on the operation piston 33 side.
The piston 33 can be easily processed, and can be manufactured at a low cost.

Further, in the case of the pump 1, an annular groove 31 which is always in communication with the bypass hole 30 (suction passage 2) is formed in the outer peripheral surface of the plunger 8 at the substantially central portion thereof. The high-pressure fuel that tends to flow out to the lifter chamber 21 through the sliding gap between the cylinder groove 16 and the lifter chamber 21 can be reliably captured by the annular groove 31. Then, only a very low pressure of the suction passage 2 acts on the oil seal 37 through the annular groove 31, so that leakage of the fuel to the lifter chamber 21 side is reliably prevented.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the following description of the embodiment, the same reference numerals are given to the same portions as those in the first embodiment, and the description of the overlapping portions will be partially omitted.

The general structure of the fuel pressurizing pump 1 of this embodiment is substantially the same as that of the first embodiment, but the shape of the passage in the plunger 108, the shape of the operating piston 133, and the retreat stroke of the plunger 108 This is greatly different from that of the first embodiment in terms of the cut area of the discharge in the first embodiment.

The fuel pressurizing pump 101 has a plunger 108 facing the pump chamber 17 as in the first embodiment.
A piston hole 127 is formed in an end surface of the piston, and an operation piston 133 is slidably fitted in the piston hole 127. In the plunger 8, a first side path 128 and a third side path 150 communicating the position near the bottom of the piston hole 127 and the bypass hole 30 on the cylinder 13 side are formed in parallel with each other while being separated in the axial direction. A second bypass 129 is formed to communicate the position near the opening of the piston hole 127 with the pump chamber 17. An annular groove 131 in which the first side path 128 and the third side path 150 are opened is formed on the outer peripheral surface at a substantially central portion of the plunger 108, and two paths 128 and 129 are always formed as bypass holes through the annular groove 131. 30.

On the other hand, on the outer peripheral surface of the operating piston 133, an annular groove 151 having a set width capable of communicating the first side path 128 and the second side path 129 is formed.
The outer peripheral surface on the tip side of this annular groove 151 is the first bypass 1
28 is a land 152 that opens and closes toward the annular groove 151. The operating piston 133 slides in the piston hole 127 in accordance with the reciprocating operation of the plunger 108, but the plunger 108 projects maximum from the cylinder 13 in FIG.
In the state shown in FIG.
When the plunger 108 is retracted by a set amount from that state, the land 152 opens the first bypass 128 toward the annular groove 131 as shown in FIGS. The path 128 and the second side path 129 communicate with each other through an annular groove 131.

The advancing / retracting position of the operating piston 133 is controlled via a stepping motor and a screw mechanism as in the first embodiment.

When the operation piston 133 is relatively displaced in the piston hole 127 due to the operation of the plunger 108 or the like, the volume of the space between the bottom of the piston hole 127 and the operation piston 133 changes. The accompanying excess or deficiency of the fuel is compensated through the third bypass 150.

In the above configuration, the operating piston 133
When the plunger 108 is displaced in the retreating direction from a state in which the plunger 108 protrudes maximally from the cylinder 13, the first side path 128 is initially set in FIG. As shown in a), the fuel in the pump chamber 17 is pressurized by the plunger 108 because it is closed by the land 152 of the operation piston 133, and the pressurized fuel is discharged by opening the discharge check valve 20. The liquid is discharged into the passage 5.

Then, when the plunger 108 retreats from this state by a set amount, the land 152 of the operating piston 133 gradually opens the first bypass 128 toward the annular groove 151 as shown in FIGS. 5B and 5C. As a result, the fuel in the pump chamber 17 flows through the second bypass 129, the annular groove 151,
The air is returned to the suction passage 2 via a bypass passage including the first bypass 128. Therefore, the fuel is not discharged to the discharge passage 5 from this point.

The characteristics of the discharge flow rate are shown in FIG. 6, and the total discharge amount per one stroke of the plunger 108 is equivalent to the area of the hatched portion in FIG.

The stroke range in which the discharge is cut in the retreating stroke of the plunger 108 is operated in accordance with the advance / retreat position of the operation piston 133, and the operation piston 133 is performed based on the control of the stepping motor. Since the stepping motor is controlled according to the operating condition of the engine, the controlled discharge flow rate depends on the operating condition of the engine.

Since the fuel pressurizing pump 101 has a structure in which the opening / closing position of the bypass passage by the plunger 108 is controlled by the position operation of the operation piston 133, similarly to the first embodiment, the control of the discharge flow rate is simple. In addition, the frequency of component operation during control is reduced, and the durability of the component is improved.

In the case of the pump of this embodiment, the pump chamber 17 is communicated with the suction passage 2 while the operation of the plunger 108 is continued in the latter half of the retreating stroke of the plunger 108 to control the timing of the end of pressurization. As compared with the first embodiment in which the timing of the start of pressurization is controlled, there is an advantage that the rapid pressure fluctuation on the discharge passage 5 side is small and the discharge flow rate control becomes smoother.

In the above description, the case where the stepping motor and the screw mechanism are used as the actuator for moving the operating piston forward and backward has been described. However, it is also possible to use a solenoid or a piezoelectric element as the actuator. When a solenoid is used, the response is better than when a stepping motor is used, and when a piezoelectric element is used, the response is improved and the effect of the reaction force from the operating piston is reduced. Less.

In each of the first and second embodiments described above, the rod-shaped operating piston is inserted into the piston hole of the plunger. However, a passage forming a bypass passage is formed in the operating piston. Alternatively, the operating piston may be arranged on the outer peripheral side of the plunger.

[0051]

As described above, according to the first aspect of the present invention, the pump chamber communicates with the suction passage, and the bypass passage opened and closed by the reciprocating operation of the plunger and the opening / closing position of the bypass passage by the plunger are operated. Operating piston, and an actuator that moves the operating piston forward and backward in accordance with the operating state of the engine,
Since the pressurization start timing or pressurization end timing by the plunger can be controlled by the position operation of the operation piston by the actuator, the discharge flow rate per one stroke of the plunger can be accurately controlled with a very simple configuration. . Therefore, according to the present invention, it is possible to manufacture at low cost, and the operation frequency of components such as the operating piston is reduced, so that the durability of the components is also improved.

According to a second aspect of the present invention, in the first aspect of the present invention, a piston hole is formed in the end face of the plunger on the pump chamber side along the axial direction. The first that communicates the position and the suction passage
A side path and a second side path communicating the pump chamber with the position near the opening of the piston hole are formed, and an operation piston capable of opening and closing the second side path can slide in the piston hole from the pump chamber side. And the closing timing of the second bypass at the time of the retreat operation of the plunger is controlled by the position operation of the operating piston, so that the pressurization start timing by the plunger is accurately controlled. It is possible to accurately control the discharge flow rate with a simple structure. In addition, the pump according to the present invention does not require processing for providing a passage or the like in the operation piston, so that processing of parts is facilitated, and as a result, there is an advantage that cost can be further reduced. .

According to a third aspect of the present invention, in the first aspect of the present invention, a piston hole is formed along an axial direction on an end face of the plunger on the pump chamber side, and further, the plunger is located near the bottom of the piston hole. The first that communicates the position and the suction passage
A side path and a second side path communicating the pump chamber with the position near the opening of the piston hole are formed, and on the outer peripheral surface of the operation piston,
An annular groove having a width capable of communicating the first side path and the second side path is formed, and the operating piston is slidably fitted in the piston hole, and the plunger is moved backward by a position operation of the operating piston. At this time, the communication timing between the first side path and the second side path through the annular groove is controlled, so that the pressurization end timing by the plunger is accurately controlled, which is an extremely simple structure. However, accurate discharge flow rate control becomes possible. Further, the pump according to the present invention controls the pump chamber to communicate with the suction passage while continuing the operation of the plunger in the latter half of the retraction stroke of the plunger. Flow rate control is possible.

According to a fourth aspect of the present invention, in the first aspect, the actuator includes a stepping motor, and a screw mechanism for converting a rotational motion of the stepping motor into a linear motion. Because
A finer control can be performed by the stepping motor, and the effect of the reaction force input to the stepping motor from the operating piston side can be reduced by the screw mechanism. Accurate control can be performed.

According to a fifth aspect of the present invention, since the actuator according to any one of the first to third aspects is constituted by a solenoid, the responsiveness of control of the operating piston can be improved.

According to a sixth aspect of the present invention, in the invention according to any one of the first to third aspects, since the actuator is constituted by a piezoelectric element, the responsiveness of the control of the operating piston can be improved, and the operating piston Since the input is hardly affected by the input, more accurate control can be performed.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of the embodiment, taken along line AA of FIG. 1;

FIG. 3 is an exemplary sectional view showing the operation of the main part of the embodiment;

FIG. 4 is a graph showing discharge flow rate-pump rotation angle characteristics of the embodiment.

FIG. 5 is a sectional view showing the operation of the main part of a second embodiment of the present invention.

FIG. 6 is a graph showing discharge flow rate-pump rotation angle characteristics of the embodiment.

[Explanation of symbols]

 1, 101: fuel pressurizing pump, 2: suction passage, 5: discharge passage, 8, 108: plunger, 13: cylinder, 17: pump chamber, 19: suction check valve, 20: discharge check valve, 27, 127 ... Piston holes (bypass passages), 28, 128: first side passage (bypass passage), 29, 129: second side passage (bypass passage), 30: bypass hole, 31, 131: annular groove (bypass passage), 33 , 133: operation piston, 34: stepping motor, 35: male screw member (screw mechanism), 36: screw hole (screw mechanism), 151: annular groove (bypass passage).

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F04B 17/05

Claims (6)

[Claims] A plunger responsive to rotation of a drive shaft is accommodated in a cylinder so as to be able to advance and retreat, and a suction chamber and a discharge path are connected to a pump chamber formed between the cylinder and the plunger via check valves. In the fuel pressurizing pump for a fuel injection device, the pump chamber and the suction passage are communicated with each other, and the bypass passage opened and closed by the reciprocating operation of the plunger, and the opening and closing position of the bypass passage by the plunger are operated. A fuel pressurizing pump for a fuel injection device, comprising: a piston; and an actuator that moves the operating piston forward and backward in accordance with an operation state of the engine. 2. An end face of the plunger on the pump chamber side,
A piston hole is formed along the axial direction. Further, the plunger further includes a first side passage communicating the position near the bottom of the piston hole and the suction passage, a position near the opening of the piston hole, and the pump chamber. Is formed, and an operating piston capable of opening and closing the second side passage is slidably fitted from the pump chamber side into the piston hole, and the plunger is retracted by operating the position of the operating piston. 2. The fuel pressurizing pump according to claim 1, wherein the closing timing of the second bypass is controlled during operation. 3. An end face on the pump chamber side of the plunger,
A piston hole is formed along the axial direction. Further, the plunger further includes a first side passage communicating the position near the bottom of the piston hole and the suction passage, a position near the opening of the piston hole, and the pump chamber. Is formed on the outer peripheral surface of the operation piston, and an annular groove having a width capable of communicating the first side passage and the second side passage is formed, and the operation piston is inserted into the piston hole. The operation timing of the first side path and the second side path through the annular groove at the time of the retreat operation of the plunger is controlled by the position operation of the operation piston by slidably fitting. 2. A fuel pressurizing pump for the fuel injection device according to claim 1. 4. The actuator according to claim 1, wherein the actuator includes a stepping motor and a screw mechanism that converts a rotational motion of the stepping motor into a linear motion. Pump for fuel pressurization of fuel injection device. 5. The fuel pressurizing pump for a fuel injection device according to claim 1, wherein said actuator is constituted by a solenoid. 6. The fuel pressurizing pump according to claim 1, wherein said actuator is constituted by a piezoelectric element.