WO2018016272A1

WO2018016272A1 - Fuel supply pump

Info

Publication number: WO2018016272A1
Application number: PCT/JP2017/023520
Authority: WO
Inventors: 幸平松下; 寛新谷; 宇王; 康雄溝渕; 徳尾　健一郎
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2016-07-22
Filing date: 2017-06-27
Publication date: 2018-01-25
Also published as: JP6689153B2; JP2018013100A

Abstract

The objective of the present invention is to provide, by means of an inexpensive structure, a relief valve structure that exhibits a stable and high fuel release characteristic and a fuel supply pump equipped with this relief valve structure. The fuel supply pump is equipped with a pressurization chamber that pressurizes a fuel, and a relief valve mechanism that returns fuel (in a discharge passage downstream from a discharge valve) to the pressurization chamber or a low-pressure passage. The relief valve mechanism is equipped with: a valve seat that closes off a relief flow passage when the relief valve is seated; a relief valve holder that holds the relief valve; and a relief spring that biases the relief valve toward the valve seat via the relief valve holder. Hole parts are formed in the relief valve holder, and the hole parts penetrate an opposing part opposing the valve seat in the axial direction of the relief valve, and reduce the flow velocity of fuel flowing between the opposing part and the valve seat when the relief valve is open.

Description

Fuel supply pump

The present invention relates to a fuel supply pump that supplies fuel to an internal combustion engine at a high pressure, and relates to a fuel supply pump including a relief valve mechanism.

Recently, vigorous efforts have been made to reduce the size, efficiency, and exhaust of internal combustion engines. In response to this, fuel supply pumps are strongly required to reduce the size of the body to improve mountability to internal combustion engines, and to increase the pressure of discharged fuel and the improvement of volumetric efficiency corresponding to high efficiency and low exhaust. .

One of the most important issues toward the further increase in pressure of the fuel supply pump, which is one of these requirements, is the development of a relief valve inside the fuel supply pump. Since the relief valve determines the maximum allowable pressure of the entire fuel supply system, there is a need for a relief valve that can be stably opened when necessary.

In this regard, various proposals have been made regarding relief valve mechanisms. Among them, for example, Patent Document 1 discloses a structure in which a fluid throttle is provided on a side surface of a relief valve to form an intermediate chamber, and a relief valve lift is increased by the pressure stored therein.

Japanese Patent No. 5103138

As an example of improving the opening characteristics of the relief valve, in the example of Patent Document 1, the pressure loss generated in the fluid throttle provided on the side surface of the relief valve causes pressure accumulation in an intermediate chamber formed between the seat portion and the fluid throttle, This is configured to act on the bottom surface of the relief valve. Thereby, the fluid force in the valve opening direction acts on the relief valve, the lift is increased, and high opening performance can be obtained.

However, with this structure, it is necessary to control the width of the clearance between the relief valve holder and the relief valve body, so strict tolerance management is required for both the relief valve holder and the relief valve body, which may increase costs. There is.

In view of the above problems, an object of the present invention is to provide a low-cost relief valve mechanism that can stably exhibit high fuel release characteristics and a fuel supply pump equipped with the relief valve mechanism.

In order to solve the above problems, the present invention comprises a pressurizing chamber for pressurizing fuel,
A relief valve mechanism for returning fuel in the discharge passage downstream of the discharge valve to the pressurizing chamber or the low-pressure passage. The relief valve mechanism is configured so that the relief valve is seated so that the relief flow path is seated. A relief valve holder that holds the relief valve, and a relief spring that urges the relief valve toward the seat portion via the relief valve holder, the relief valve holder Has a hole that reduces the flow velocity of the fuel flowing between the facing portion and the seat portion when the relief valve is opened, penetrating in the relief valve axial direction at the facing portion facing the seat portion It was done.

According to the configuration of the present invention, a relief valve mechanism that stably exhibits a high fuel release characteristic and a fuel supply pump equipped with the relief valve mechanism can be realized with an inexpensive structure.

The figure which shows the cross section of the relief valve 30 which concerns on Example 1 of this invention. The figure which shows the whole structure of the fuel supply pump system with which the Example of this invention is applied. The flow velocity distribution in the relief valve 30 which concerns on Example 1 of this invention is shown. The pressure distribution in the relief valve 30 which concerns on Example 1 of this invention is shown. The figure which shows the cross section of the relief valve 30 which concerns on Example 1 of this invention. The figure which shows the cross section of the relief valve 30 which concerns on Example 1 of this invention. The figure which shows the cross section of the relief valve 30 which concerns on Example 2 of this invention. The figure which shows the cross section of the relief valve 30 which concerns on Example 3 of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Examples will be described with reference to FIGS. FIG. 2 shows the overall configuration of a fuel supply pump system to which the fuel supply pump 300 of the present invention is applied. First, the overall configuration will be described with reference to FIG. 2, and then each embodiment of the relief valve mechanism will be described.

The fuel supply pump system in FIG. 2 is roughly divided into a fuel tank 101 on the left side in the figure, a fuel supply pump 300 in the center in the figure, a fuel injection system 200 (common rail 53, injector 54, etc.) on the right side in the figure, and an engine control unit (ECU) 40. The internal combustion engine 400 to which the fuel supply pump 1 and the injector 54 in the lower center of the figure are attached is configured.

The fuel supply pump 300 incorporates a plurality of parts and mechanisms in the body 1 and is attached to the cylinder head 20 of the internal combustion engine 400. In the body 1, a suction passage 9, a pressurizing chamber 11, a discharge passage 12, and a relief passage 15 are formed. An electromagnetic suction valve 5 is provided in the suction passage 9, a discharge valve 8 is provided in the discharge passage 12, and a relief valve 30 is provided in the relief passage 15. The pressurizing chamber 11 in the body 1 is changed in volume by the plunger 2 that moves up and down by the rotation of the cam 7 of the internal combustion engine, so that the pump operation is possible.

Briefly describing the function of each of the above-described valves formed in the fuel supply pump 300, the electromagnetic intake valve 5 is an adjustment valve that determines the amount of fuel to be pressurized. The discharge valve 8 is a check valve that restricts the direction of fuel flow. The relief valve 30 functions as a safety valve that opens the abnormal high-pressure fuel when the pressure in the common rail 53 becomes abnormally high or higher than the set pressure.

According to the fuel supply pump system, the fuel from the fuel tank 101 is guided into the fuel supply pump 300 and passes through the electromagnetic suction valve 5 in the suction passage 9, the pressurizing chamber 11, and the discharge valve 8 in the discharge passage 12. The pressure is increased and applied to the fuel injection system 200. The fuel supply pump 300 is connected to the common rail 53 of the fuel injection system 200, the pressurized fuel is pumped, and the high-pressure fuel is injected from the injector 54 into the combustion chamber of the internal combustion engine. The pressure in the common rail 53 is measured by the pressure sensor 56, and the signal is sent to the engine control unit (ECU) 40. The injectors 54 are mounted in accordance with the number of cylinders of the engine, and inject fuel with a signal from an engine control unit (ECU) 40. The engine control unit (ECU) 40 controls the electromagnetic intake valve 5 in the fuel supply pump.

2 The fuel supply pump system in FIG. 2 is configured as described above. First, each function of the fuel supply pump will be described in more detail.

First, the connection relationship with the internal combustion engine for causing the pressurizing chamber 11 to perform the pump operation will be described. The plunger 2 is inserted into a recessed hole formed in the body 1 from the side opposite to the pressurizing chamber 11 (the lower side in FIG. 2). The plunger 2 is slidably inserted into the cylinder 120, and a retainer 3 is attached to the lower end of the plunger 2. The urging force of the plunger return spring 4 acts on the retainer 3 in the direction toward the cam attached to the camshaft in FIG. 2 (downward direction in FIG. 2). The tappet 6 reciprocates in the vertical direction in FIG. 2 by the rotation of the cam 7 of the internal combustion engine. Since the plunger 2 is displaced following the tappet 6, this changes the volume of the pressurizing chamber 11 and enables a pressurizing operation.

Next, the configuration of the electromagnetic intake valve 5 in the fuel supply pump controlled by a signal from the engine control unit (ECU) 40 will be described. The electromagnetic suction valve 5 is held by the body 1, and an electromagnetic coil 500, a mover 503, an anchor spring 502, and a suction valve valve spring 504 are arranged. Hereinafter, the description will be made on the assumption that the movable portion 503 is formed of one member. However, the movable portion 503 may be formed of two members including an anchor that forms a magnetic attraction surface and a rod that forms a sliding portion. Good.

Hereafter, the explanation will proceed on the premise of a system using a normally open type electromagnetic suction valve. An electromagnetic suction valve that opens when the electromagnetic coil 500 is OFF and closes when the electromagnetic coil 500 is ON is referred to as a normally open system. The urging force of the anchor spring 502 acts on the relief valve 501 via the movable portion 503 in the valve opening direction, and similarly, the urging force of the suction valve spring 504 acts on the relief valve 501 in the valve closing direction. Here, since the urging force of the anchor spring 502 is larger than the urging force of the suction valve spring 504, the suction valve 501 is in an open state when the electromagnetic coil 500 is OFF (non-energized). The operation is reversed, that is, similarly to the fuel supply pump of an electromagnetic intake valve called a normally closed system in which the intake valve 501 is closed when the electromagnetic coil 500 is OFF (no power supply). The present invention can be applied.

The relief valve 30 is formed by a relief valve 152 and a seat member 151. In the following description, the pressure valve return type relief valve 30 will be described. A method of opening the abnormal high pressure generated on the common rail 53 side to the pressurizing chamber 11 is referred to as a pressurizing chamber returning method.

The relief valve 30 in FIG. 2 is formed in the relief passage 15, and the relief passage 15 is connected to the downstream side (fuel injection system 200 side) of the discharge valve 8 and the pressurizing chamber 11. A relief valve 152 is arranged in a direction to open from the downstream side to the pressurizing chamber 11 side. The relief valve 152 is urged to the seat member 151 by a relief spring 154, and a seat portion 150 that seals fuel is formed in the seat member 151 at a contact portion between the two. The behavior of the relief valve 152 is determined by the differential pressure generated before and after the relief valve 152. That is, the pressure on the upstream side of the relief valve 152 (the pressure on the downstream side of the discharge valve 8) becomes larger than the pressure on the downstream side of the relief valve 152 (the pressure in the pressurizing chamber 11). When the urging force of the spring 154 is overcome, the valve opening operation is started. The present invention can be similarly applied to a system using a low pressure return system in which the relief passage 15 is connected to the downstream side of the discharge valve 8 and the damper chamber 51.

Next, the operation of the fuel supply pump 300 and the flow rate control method will be described. A state in which the plunger 2 is displaced downward in FIG. 2 due to rotation of the cam 7 of the internal combustion engine is referred to as an intake process, and a state in which the plunger 2 is displaced upward is referred to as an ascending process. The ascending process includes a return stroke and a compression stroke, which will be described later. In the suction process, the volume of the pressurizing chamber 11 increases and the fuel pressure therein decreases. In this suction process, when the fuel pressure in the pressurizing chamber 11 becomes lower than the fuel pressure in the suction passage 9, the suction valve 501 of the electromagnetic suction valve 5 is opened and fuel is sucked into the pressurizing chamber 11.

Since the electromagnetic coil 500 is in the OFF state in the suction process, the urging force of the anchor spring 502 is moved through the movable portion 503 in the direction to open the rod portion at the tip (right direction in FIG. 2). Yes. Next, when the plunger 2 moves from the suction process to the ascending stroke, the electromagnetic coil 500 of the electromagnetic suction valve 5 is kept in an OFF state, so that the movable portion 503 and the rod portion at the distal end are in the valve open position. Retained. In this state, when the plunger 2 is raised, the suction valve 501 moves in the valve closing direction (left direction in FIG. 2) to close, but collides with the rod portion at the tip of the movable portion 503 in the valve opening position. Therefore, the valve cannot be closed and the valve open state is maintained.

Thus, in the ascending process, the pressure in the pressurizing chamber 11 maintains a low pressure state substantially equal to that of the suction passage 9, so that the discharge valve 8 cannot be opened. It passes through the electromagnetic suction valve 5 and is returned to the damper chamber 51 side. This process is called a return process. As a result, only the necessary flow rate is pressurized and discharged, and the flow rate can be controlled.

Next, when the electromagnetic coil 500 of the electromagnetic intake valve 5 is energized in the return step, a magnetic attractive force acts on the mover 503 to overcome the urging force of the anchor spring 502, and the movable portion 503 and the rod portion of the electromagnetic intake valve 5 are moved. It moves in the valve closing direction (left direction in FIG. 2) and is held in the valve closing position. In this state or when the movable portion 503 moves in the valve closing direction, the suction valve 501 is closed by the biasing force of the suction valve spring 504 and the fluid differential pressure of the return fuel. When the intake valve 501 is closed, the fuel pressure in the pressurizing chamber 11 increases with the rise of the plunger 2 immediately after this, so that a compression stroke is formed. As a result, the discharge valve 8 is automatically opened, and the fuel is pumped to the common rail 53.

If the electromagnetic suction valve 5 operating as described above is used, the flow rate discharged by the pump can be controlled by adjusting the timing at which the electromagnetic coil 500 is turned on.

FIG. 1 shows a sectional view of a relief valve mechanism 30 according to the first embodiment. As shown in FIG. 1, the relief valve mechanism 30 of this embodiment includes a relief housing 155, and the relief housing 155 is press-fitted into a hole formed in the body 1 of the fuel supply pump 300. In FIG. 1, the relief housing 155 is configured integrally with the sheet member 151, but may be configured separately.

The ball valve 152a of the relief valve mechanism 30 is urged by a relief spring 154 in the direction of the seat member 151 via the relief valve holder 152b, and a seat portion 150 that seals fuel is formed at the contact portion between the two. Yes. The behavior of the relief valve 152 is governed by the differential pressure generated before and after the relief valve 152. The relief valve holder 152b is urged by the relief spring 154 to urge the ball valve 152a against the seat portion 150. The ball valve 152a and the relief valve holder 152b together constitute a relief valve 152. Although both can be formed as one member, the processing cost can be reduced by using a commercially available material for the ball valve 152a.

This is caused by the pressure difference between the pressure on the upstream side (right side in FIG. 1) of the relief valve 152 (downstream pressure on the discharge valve 8) and the pressure on the downstream side (left side in FIG. 1) (pressure in the pressurizing chamber 11). When the urging force exceeds the urging force of the relief spring 154, the relief valve 152 starts to open in the downstream direction.
The relief spring 154 is supported on the outer periphery of the spring support member 158, and the spring support member 158 is fixed to the relief housing 155 by press fitting. By adjusting the press-fitting depth of the spring support member 158, it is possible to adjust the biasing force of the relief spring 154 and change the differential pressure (set pressure) at which the valve opening operation starts.

As described above, the fuel supply pump 300 of this embodiment uses the pressurizing chamber 11 for pressurizing the fuel and the fuel in the discharge passage on the downstream side of the discharge valve 8 in the pressurizing chamber 11 or the low-pressure passage (the suction passage 9, the damper chamber 51). And a relief valve mechanism 30 for returning to (). The relief valve mechanism 30 includes a seat portion 150 that closes the relief flow path (relief passage 15) when the relief valve 152a is seated, a relief valve holder 152b that holds the relief valve 152a, and a relief valve holder 152b. And a relief spring 154 that urges the relief valve 152a toward the seat portion 150.

Then, the relief valve holder 152b penetrates in the relief valve axial direction (left and right direction in FIG. 1) in the facing portion 156 (upstream side surface portion) facing the seat portion 150, and the facing portion when the relief valve 152a is opened. A hole 153 for reducing the flow velocity of the fuel flowing between 156 (upstream side surface portion) and the seat portion 150 was formed.

FIG. 3 shows a flow velocity distribution diagram around the relief valve when there is no hole 153 and when there is no hole 153.
It can be seen from FIG. 3 that when the relief valve 152 is opened by the hole portion 153, the flow rate of the fuel flowing between the facing portion and the seat portion 151 is reduced. FIG. 4 shows the pressure distribution around the relief valve when the hole 153 is not present and when it is not present. It can be seen from FIG. 4 that the fuel pressure between the facing portion 156 and the seat portion 150 is increased. Since the pressure increases, the fluid force acting in the direction in which the relief valve 152 opens increases, and the opening performance of the relief valve 152 can be improved. The inventors have confirmed by analysis that the fluid force applied to the relief valve 152 is increased by providing the hole 153.

Here, the hole 153 is desirably formed on the inner peripheral side with respect to the outermost peripheral portion 159 of the facing portion 156 of the relief valve holder 152b. If the hole 153 is formed on the outer peripheral side with respect to the outermost peripheral portion 159 of the opposing portion of the relief valve holder 152b, the area of the upstream pressure receiving portion of the relief valve 152 may not be ensured. On the other hand, according to the said structure, this possibility can be suppressed and the area of the upstream pressure receiving part 156 of the relief valve 152 can be ensured.

Further, as shown in the sectional view of the relief valve mechanism 30 in FIG. 5, it is desirable that the tangent line 157 drawn to the seat surface of the seat portion 150 is overlapped with the seat portion side end surface 153b of the hole portion.

If the tangent line 157 drawn to the seat surface of the seat portion 150 is configured so as to be disengaged from the seat portion side end surface 153b of the hole portion 153, the fuel flowing from the upstream side may not easily flow into the hole portion 153. On the other hand, according to the said structure, this possibility is suppressed and the fuel which flows in from an upstream becomes easy to flow in the hole 153. FIG. The number of holes is arbitrary, but the number of holes is preferably four or more from the viewpoint of maintaining balance when the relief valve is lifted. Further, it is desirable that the hole 153 is substantially parallel to the axial direction of the relief valve 152.

When the hole 153 is displaced from the direction parallel to the axial direction of the relief valve 152, the fuel hardly flows into the hole 153, and the fuel easily flows between the facing portion and the seat portion 150. Then, the fuel flow velocity between the facing portion 156 and the seat portion 150 increases, and the fuel pressure between the facing portion 156 and the seat portion 150 decreases. For this reason, the fluid force applied in the lift direction of the relief valve 152 is lowered, and the opening performance of the relief valve 152 may be lowered. On the other hand, with this configuration, this possibility can be suppressed and the opening performance of the relief valve 152 can be enhanced.

Further, as shown in the sectional view of the relief valve valve mechanism 30 in FIGS. 1 and 5, the relief valve valve holder is disposed on the outermost peripheral portion 159 and the outer peripheral side of the relief valve valve holder 152b, and is opposed to the outermost peripheral portion 159. It is desirable that the gap 160 with the opposing surface of the relief housing 155 to be 0.2 mm or more. In FIG. 4, the outermost peripheral portion 159 is shown on the same surface as the facing portion 156, but the position of the outermost peripheral portion 159 is not limited to this.

If the clearance between the outermost peripheral portion 159 of the relief valve valve holder 152b and the opposing surface of the relief housing 155 that is disposed on the outer peripheral side of the relief valve valve holder 152b and faces the outermost peripheral portion 159 is 0.2 mm or less, a tolerance is required. Management becomes stricter and the cost of manufacturing the fuel supply pump increases. With the above configuration, this can be suppressed and the cost for manufacturing the fuel pump can be reduced.

Further, as shown in the sectional view of the relief valve mechanism 30 in FIG. 6, in a state where the relief valve 152 is opened at the maximum opening degree, the facing member 156 of the relief valve holder 152b and the seat member 151 facing substantially parallel thereto. It is desirable that the gap with the opposite surface is equal to or smaller than the hole diameter of the hole 153. If the clearance is 0.2 mm or less as described above, the differential pressure between the upstream surface and the downstream surface of the relief valve increases, so that the fluid force applied to the relief valve can be increased. When the relief valve 152 is opened at an opening, the gap between the facing portion 156 of the relief valve holder 152b and the facing surface of the seat member 151 facing substantially parallel thereto is equal to or larger than the hole diameter of the hole portion 153. The fluid force acting on the relief valve holder 152b may reduce the opening performance of the relief valve 30. With the above configuration, this can be suppressed and the opening performance of the relief valve can be improved. In the present embodiment, in a state where the relief valve 152a is opened, all the flow paths from the seat portion 150 to the downstream side of the relief valve holder 150b are configured to be 0.1 mm or more.

FIG. 7 shows a cross-sectional view of the relief valve mechanism according to the second embodiment of the present invention. In FIG. 8, 1 is a pump body, 150 is a seat portion, 153 is a hole portion, 154 is a relief spring, 155 is a housing, 151 is a seat member, 156 is an intermediate chamber, 156 is an opposing portion (upstream pressure receiving surface), 158 Represents spring support members, respectively.

In the second embodiment, three or more holes 153 that are one place in the first embodiment are arranged. By increasing the number of holes, the flow field can be symmetric with respect to the central axis of the relief valve 152, so that the inclination of the relief valve 152 can be suppressed.

FIG. 8 shows a sectional view of the relief valve mechanism 30 according to the third embodiment of the present invention. In FIG. 7, 1 is a pump body, 150 is a seat portion, 153 is a hole portion, 154 is a relief spring, 155 is a housing, 151 is a seat member, 156 is an intermediate chamber, 156 is a facing portion (upstream pressure receiving surface), 158 Represents spring support members, respectively.

In the third embodiment, the hole 153 is formed in communication with the recess of the relief valve holder 152b. With the above configuration, the fuel easily flows into the hole 153. And it becomes difficult for a fuel to flow between the opposing part 156 and the sheet | seat member 151. FIG. Since the fuel flow velocity between the facing portion 156 and the seat member 151 decreases and the pressure of the fuel between the facing portion 156 and the seat member 151 increases from Bernoulli's theorem, the flow applied in the lift direction of the relief valve 152 Increases physical strength. Therefore, the opening performance of the relief valve 152 can be enhanced. Analysis has confirmed that a higher fluid force is applied to the relief valve when the hole 153 is formed in communication with the recess of the relief holder 152b than when the hole 153 is formed away from the recess. .

In addition, it is desirable that the sectional area of the hole 153 when viewed in the axial direction of the relief valve 152 is 1/300 or more than the sectional area of the relief valve holder.

When the sectional area of the hole 153 when viewed in the axial direction of the relief valve 152 is less than 1/300 of the sectional area of the relief valve holder 152b, the fuel cannot pass through the hole 153, and the seat member The fuel flows between the counter portion 156 of the relief valve holder 152b and the flow velocity increases. From Bernoulli's theorem, the pressure generated between the seat member 151 and the facing portion 156 of the relief valve holder 152b is reduced, and the fluid force acting on the relief valve 152 is reduced. Therefore, the opening performance of the relief valve 152 may be reduced. With the above configuration, this can be suppressed and the opening performance of the relief valve 152 can be enhanced.

The present invention is widely applicable not only to the fuel supply pump of an internal combustion engine but also to various high-pressure pumps.

1: Body 2: Plunger 3: Retainer 4: Return spring 5: Electromagnetic suction valve 6: Tappet 7: Cam 8: Discharge valve 9: Suction passage 11: Pressurizing chamber 12: Discharge passage 15: Relief passage 150: Seat portion 151 : Valve seat 152: Relief valve 152 a: Ball valve 152 b: Relief valve holder 153: Hole 154: Relief spring 155: Housing 156: Upstream pressure receiving surface 157: Tangential line 158 drawn on the seat surface: Spring support member 53: Common rail 54 : Injector 56: Pressure sensor

Claims

A pressurizing chamber for pressurizing the fuel;
In a fuel supply pump comprising a relief valve mechanism for returning fuel in a discharge passage downstream of the discharge valve to the pressurizing chamber or the low pressure passage,
The relief valve mechanism is
A seat portion that closes the relief flow path by the seating of the relief valve;
A relief valve holder for holding the relief valve;
A relief spring that urges the relief valve toward the seat portion via the relief valve holder,
The relief valve holder penetrates in the relief valve axial direction at the facing portion facing the seat portion, and reduces the flow rate of fuel flowing between the facing portion and the seat portion when the relief valve is opened. A fuel supply pump having a hole to be formed.
The fuel supply pump according to claim 1, wherein
The said hole is a fuel supply pump formed in the inner peripheral side with respect to the outermost peripheral part of the said opposing part of the said relief valve holder.
The fuel supply pump according to claim 1, wherein
The hole portion is a fuel supply pump configured such that a tangent line drawn to a seat surface of the seat portion overlaps a seat portion side end surface of the hole portion.
The fuel supply pump according to claim 1, wherein
A fuel supply pump configured such that all the flow paths from the seat portion to the downstream side of the relief valve holder are equal to or smaller than the hole diameter of the hole portion in a state where the relief valve is opened.
The fuel supply pump according to claim 1, wherein
The hole is a fuel supply pump formed substantially in parallel with the relief valve axial direction.
The fuel supply pump according to claim 1, wherein
A fuel supply pump formed so that a sectional area of the hole when viewed in the relief valve axial direction is 1/300 or more of a sectional area of the relief valve holder.
The fuel supply pump according to claim 1, wherein
The hole is a fuel supply pump formed at least at three or more locations in the facing portion of the relief valve holder.
The fuel supply pump according to claim 1, wherein
The relief valve holder is formed with a recess for holding the relief valve, and the hole is formed in communication with the recess of the relief valve holder.