JP6959109B2 - Relief valve mechanism and fuel supply pump equipped with it - Google Patents

Description

The present invention relates to a relief valve mechanism and a fuel supply pump including the relief valve mechanism.

In order to reduce the pressure loss of the check valve installed in the fuel supply pump, it is known that the fuel flow is bent in a plurality of times in the vicinity of the seat portion that seals the fuel by contacting the valve. (See, for example, Patent Document 1).

In Patent Document 1, "the seat surface is followed by at least one surface on the side facing the section having a relatively large diameter, and the surface is inclined more than the seat surface with respect to the longitudinal axis of the connection portion. Attached, the seat surface is followed by at least one surface on the side facing the section having a relatively small diameter, which surface is inclined less than the seat surface with respect to the longitudinal axis of the connection. It is characterized by being. "

Special Table 2007-533882A

In the technique disclosed in Patent Document 1, when the flow is rapidly expanded in order to reduce the pressure loss, cavitation may occur due to the separation of the flow. In addition, when applying to a relief valve with a high load of the return spring, if the valve body is directly urged by the return spring, wear may occur at the contact part, so relief between the valve body and the return spring. It is desirable to sandwich the valve holder. In such a case, if the technique disclosed in Patent Document 1 is applied, it is difficult to secure a space for arranging the relief valve holder and to form a flow that smoothly wraps around the relief valve holder.

An object of the present invention is to provide a fuel supply pump that can prevent cavitation corrosion in the relief valve seat portion when the pressure is increased and reduce the pressure loss when the abnormal high pressure is released.

In order to achieve the above object, in the present invention, a relief valve and a seat portion on which the relief valve is seated are formed, and a seat surface inclined at a first angle with respect to the valve axis direction and a seat surface downstream of the seat portion. A downstream inner diameter expanding portion formed by connecting with the lower end of the seat surface so as to expand radially outward from the seat surface, and a downstream side formed radially outward from the lower end of the downstream inner diameter expanding portion. The upstream inner diameter is expanded by connecting the end face and the upstream end of the seat surface on the upstream side of the seat portion and inclining from the downstream end of the introduction passage at a fifth angle smaller than the first angle with respect to the valve axis direction. comprising a part, a plurality including a connecting point between the introduction passage and the upstream inner diameter enlarged portion, and a connection point between the upstream side large inner diameter portion and the seat surface, and a connection point between the seat surface and the downstream side inner diameter enlarged portion in terms of, the farther the distance from the seat portion to each point, that is formed such that the angle of direction change of the flow at each point is large.

According to the present invention, it is possible to provide a fuel supply pump that can prevent cavitation corrosion in the relief valve seat portion at the time of increasing the pressure and reduce the pressure loss at the time of releasing the abnormal high pressure. Issues, configurations and effects other than those described above will be clarified by the description of the following embodiments.

It is a vertical sectional view seen from the horizontal direction of the fuel supply pump which carries out this invention. It is a horizontal sectional view seen from the upper direction of the fuel supply pump which carries out this invention. It is a vertical sectional view seen from the horizontal direction different from FIG. 1 of the fuel supply pump which carries out this invention. It is an enlarged sectional view of the electromagnetic intake valve mechanism mounted on the fuel supply pump which carries out this invention. It is a block diagram of the fuel supply system including the fuel supply pump which carries out this invention. It is an enlarged sectional view around the seat member of the relief valve mechanism by 1st Embodiment of this invention. It is an enlarged cross-sectional view around the seat member of the relief valve mechanism by the modification of 1st Embodiment of this invention. It is an enlarged cross-sectional view around the seat member of the relief valve mechanism by the 2nd Embodiment of this invention. It is an enlarged cross-sectional view around the seat member of the relief valve mechanism by the modification of the 2nd Embodiment of this invention.

Hereinafter, examples of the present invention will be described in detail with reference to the drawings. In the following description, the vertical direction in the drawings may be specified, but this vertical direction does not mean the vertical direction in the mounted state of the fuel supply pump.

FIG. 5 is a configuration diagram showing an example of a fuel supply system including a fuel supply pump. The portion surrounded by the broken line indicates the pump body 1 of the fuel supply pump, and the mechanism and parts shown in the broken line indicate that the pump body 1 of the fuel supply pump is integrally incorporated.

The fuel in the fuel tank 20 is pumped by the feed pump 21 based on a signal from the engine control unit (ECU) 21. This fuel is pressurized to an appropriate feed pressure and sent to the low pressure fuel suction port 10a of the fuel supply pump through the suction pipe 28. The fuel that has passed through the suction joint 51 from the low-pressure fuel suction port 10a reaches the suction port 31b of the electromagnetic suction valve mechanism 300 that constitutes the capacity variable mechanism via the pressure pulsation reduction mechanism 9 and the suction passage 10d.

The fuel that has flowed into the electromagnetic suction valve mechanism 300 passes through the suction valve 30 and flows into the pressurizing chamber 11. The engine cam mechanism 93 (see FIG. 1) gives the plunger 2 reciprocating power. Due to the reciprocating motion of the plunger 2, fuel is sucked from the suction valve 30 in the descending stroke of the plunger 2, and the fuel is pressurized in the ascending stroke. The pressurized fuel is pressure-fed to the common rail 23 on which the pressure sensor 26 is mounted via the discharge valve mechanism 8.

The common rail 23 is equipped with an injector 24 (so-called direct injection injector) that injects fuel directly into an engine cylinder (not shown) and a pressure sensor 26. The direct-injection injector 24 is mounted according to the number of cylinders (cylinders) of the engine, and opens and closes according to a control signal of the ECU 27 to inject fuel into the cylinders. The fuel supply pump (fuel supply pump) of this embodiment is applied to a so-called direct injection engine system in which the injector 24 injects fuel directly into the cylinder of the engine.

When an abnormally high pressure is generated in the common rail 23 due to a failure of the direct injection injector 24 or the like, the differential pressure between the pressure of the fuel discharge port 12 of the fuel supply pump and the pressure of the pressurizing chamber 11 becomes equal to or higher than the valve opening pressure of the relief valve mechanism 200. Then, the relief valve 202 opens. In this case, the fuel having an abnormally high pressure on the common rail 23 passes through the inside of the relief valve mechanism 200 and is returned from the relief passage 200a to the pressurizing chamber 11. This makes it possible to protect the common rail 23 (high pressure piping). The present invention can also be applied to a method in which the relief passage 200a is connected to the low pressure fuel chamber 10 (see FIG. 1) and the fuel having an abnormally high pressure is returned to the low pressure passage.

The fuel supply pump of this embodiment will be described with reference to FIGS. 1, 2 and 3. FIG. 1 is a cross-sectional view showing a cross section of the fuel supply pump of the present embodiment parallel to the central axis direction of the plunger. FIG. 2 is a cross-sectional view in the horizontal direction of the fuel supply pump of this embodiment as viewed from above. FIG. 3 is a cross-sectional view of the fuel supply pump of this embodiment as viewed from a direction different from that of FIG.

Although the suction joint 51 is provided on the side surface of the body in FIG. 2, the present invention is not limited to this, and the suction joint 51 is also applied to a fuel supply pump provided on the upper surface of the damper cover 14. It is possible. The suction joint 51 is connected to a low-pressure pipe that supplies fuel from the fuel tank 20 of the vehicle, and the fuel that has flowed in from the low-pressure fuel suction port 10a of the suction joint 51 is a low-pressure flow path formed inside the pump body 1. Flow. A suction filter (not shown) press-fitted into the pump body 1 is provided at the inlet of the fuel passage formed in the pump body 1, and the suction filter contains foreign matter existing between the fuel tank 20 and the low-pressure fuel suction port 10a. Prevents inflow into the fuel supply pump.

The fuel flows from the suction joint 51 upward in the plunger axial direction, and flows into the low-pressure fuel chamber 10 formed by the upper damper 10b and the lower damper 10c shown in FIG. The low-pressure fuel chamber 10 is formed by being covered with a damper cover 14 attached to the pump body 1. The fuel whose pressure pulsation is reduced by the pressure pulsation reducing mechanism 9 in the low pressure fuel chamber 10 reaches the suction port 31b of the electromagnetic suction valve mechanism 300 via the low pressure fuel flow path 10d. The electromagnetic suction valve mechanism 300 is attached to a lateral hole formed in the pump body 1 and supplies a desired flow rate of fuel to the pressurizing chamber 11 via the pressurizing chamber inlet flow path 1a formed in the pump body 1. An O-ring 61 is fitted into the pump body 1 for sealing between the cylinder head 90 and the pump body 1 to prevent engine oil from leaking to the outside.

As shown in FIG. 1, a cylinder 6 for guiding the reciprocating motion of the plunger 2 is attached to the pump body 1. The cylinder 6 is fixed to the pump body 1 by press fitting and caulking on the outer peripheral side thereof. The surface of the cylindrical press-fitting portion of the cylinder 6 seals the pressurized fuel from the gap with the pump body 1 so as not to leak to the low pressure side. By bringing the upper end surface of the cylinder 6 into contact with the flat surface of the pump body 1 in the axial direction, the cylinder 6 forms a double seal structure in addition to the seal of the cylindrical press-fitting portion between the pump body 1 and the cylinder 6.

A tappet 92 is provided at the lower end of the plunger 2 to convert the rotational motion of the cam 93 attached to the camshaft of the internal combustion engine into a vertical motion and transmit it to the plunger 2. The plunger 2 is crimped to the tappet 92 by a spring 4 via a retainer 15. As a result, the plunger 2 can be reciprocated up and down with the rotational movement of the cam 93.

Further, the plunger seal 13 held at the lower end of the inner circumference of the seal holder 7 is installed in a slidable contact with the outer periphery of the plunger 2 at the lower portion in the drawing of the cylinder 6. As a result, when the plunger 2 slides, the fuel in the sub chamber 7a is sealed and prevented from flowing into the internal combustion engine. At the same time, the plunger seal 13 prevents the lubricating oil (including the engine oil) that lubricates the sliding portion in the internal combustion engine from flowing into the inside of the pump body 1.

As shown in FIG. 2, the pump body 1 has a horizontal hole for mounting the electromagnetic suction valve mechanism 300, a horizontal hole for mounting the discharge valve mechanism 8 at the same position in the plunger axial direction, and a horizontal hole for mounting the relief valve mechanism 200. A horizontal hole for attaching the discharge joint 12c is formed. The fuel pressurized in the pressurizing chamber 11 via the electromagnetic suction valve mechanism 300 flows through the discharge passage 12b via the discharge valve mechanism 8 and is discharged from the fuel discharge port 12 of the discharge joint 12c.

The discharge valve mechanism 8 (FIGS. 2 and 3) provided on the outlet side of the pressurizing chamber 11 directs the discharge valve seat 8a, the discharge valve 8b that comes into contact with and separates from the discharge valve seat 8a, and the discharge valve 8b toward the discharge valve seat 8a. It is composed of a discharge valve spring 8c for urging, a discharge valve plug 8d, and a discharge valve stopper 8e for determining a stroke (moving distance) of the discharge valve 8b. The discharge valve plug 8d and the pump body 1 are joined by a welded portion 401, which cuts off the inner space through which fuel flows and the outside. Further, the discharge valve sheet 8a is joined to the pump body 1 by the press-fitting portion 402.

When there is no differential pressure between the fuel pressure in the pressurizing chamber 11 and the fuel pressure in the discharge valve chamber 12a, the discharge valve 8b is crimped to the discharge valve seat 8a by the urging force of the discharge valve spring 8c and is in a closed state. .. Only when the fuel pressure in the pressurizing chamber 11 becomes higher than the fuel pressure in the discharge valve chamber 12a does the discharge valve 8b open against the discharge valve spring 8c. Then, the high-pressure fuel in the pressurizing chamber 11 is discharged to the common rail 23 through the discharge valve chamber 12a, the discharge passage 12b, and the fuel discharge port 12. When the discharge valve 8b is opened, it comes into contact with the discharge valve stopper 8e and the stroke is limited. Therefore, the stroke of the discharge valve 8b is appropriately determined by the discharge valve stopper 8e. As a result, it is possible to prevent the fuel discharged at high pressure into the discharge valve chamber 12a from flowing back into the pressurizing chamber 11 due to the delay in closing the discharge valve 8b due to the stroke being too large, and the efficiency of the fuel supply pump is reduced. Can be suppressed. Further, the discharge valve 8b is guided on the outer peripheral surface of the discharge valve stopper 8e so that the discharge valve 8b moves only in the stroke direction when the discharge valve 8b repeats the valve opening and closing operations.

As described above, the pressurizing chamber 11 is composed of the pump body 1, the electromagnetic suction valve mechanism 300, the plunger 2, the cylinder 6, and the discharge valve mechanism 8. Further, as shown in FIGS. 2 and 3, the fuel supply pump of this embodiment uses the mounting flange 1b provided on the pump body 1 to be in close contact with the plane of the cylinder head 90 of the internal combustion engine, and is fixed by a plurality of bolts (not shown). Will be done.

The relief valve mechanism 200 is composed of a seat member 201, a relief valve 202, a relief valve holder 203, a relief spring 204, and a holder member 205. The relief valve mechanism 200 is a valve configured to operate when a problem occurs in the common rail 23 or a member beyond the common rail 23 and the pressure becomes abnormally high, and the pressure in the common rail 23 or the member beyond the common rail 23 becomes high. In such a case, the valve is opened and the fuel is returned to the pressurizing chamber 11 or the low pressure passage (low pressure fuel chamber 10 or suction passage 10d, etc.). Therefore, it is necessary to maintain the valve closed state below a predetermined pressure, and it has a very strong spring 204 to counter the high pressure.

The electromagnetic suction valve mechanism 300 will be described with reference to FIG. FIG. 4 is an enlarged cross-sectional view showing a cross section of the electromagnetic suction valve mechanism of the present embodiment parallel to the driving direction of the suction valve, and is a cross-sectional view showing a state in which the suction valve is opened.

In the non-energized state, the suction valve 30 is operated in the valve opening direction by the strong rod urging spring 40, so that it is a normally open type. When the control signal from the ECU 27 is applied to the electromagnetic suction valve mechanism 300, a current flows through the electromagnetic coil 43 via the terminal 46. When a current flows through the electromagnetic coil 43, the movable core 36 is attracted to the valve closing direction by the magnetic attraction force of the magnetic core 39 on the magnetic attraction surface S. The rod urging spring 40 is arranged in the recessed portion formed in the magnetic core 39 and urges the flange portion 35a. The flange portion 35a engages with the recessed portion of the movable core 36 on the side opposite to the rod urging spring 40.

The magnetic core 39 is configured to come into contact with a lid member 44 that covers the electromagnetic coil chamber in which the electromagnetic coil 43 is arranged. When the movable core 36 is attracted to the magnetic core 39 and moves, the flange portion 35a of the rod 35 engages with the movable core 36, and the rod 35 moves in the valve closing direction together with the movable core 36. Between the movable core 36 and the suction valve 30, a valve closing urging spring 41 that urges the movable core 36 in the valve closing direction and a rod guide member 37 that guides the rod 35 in the on-off valve direction are arranged. NS. The rod guide member 37 constitutes a spring seat 37b of the valve closing urging spring 41. Further, the rod guide member 37 is provided with a fuel passage 37a, which enables fuel to flow in and out of the space in which the movable core 36 is arranged.

The movable core 36, the valve closing spring 41, the rod 35, and the like are included in the electromagnetic suction valve mechanism housing 38 fixed to the pump body 1. Further, the magnetic core 39, the rod urging spring 40, the electromagnetic coil 43, the rod guide member 37 and the like are held in the electromagnetic suction valve mechanism housing 38. The rod guide member 37 is attached to the electromagnetic suction valve mechanism housing 38 on the side opposite to the magnetic core 39 and the electromagnetic coil 43, and includes the suction valve 30, the suction valve urging spring 33, and the stopper 32. do.

A suction valve 30, a suction valve urging spring 33, and a stopper 32 are provided on the side of the rod 35 opposite to the magnetic core 39. The suction valve 30 is formed with a guide portion 30b that projects toward the pressurizing chamber 11 and is guided by the suction valve urging spring 33. The suction valve 30 moves in the valve opening direction (direction away from the valve seat 31a) by the gap of the valve body stroke 30e as the rod 35 moves, so that the valve is opened, and the suction valve 30 is brought into the valve opening state from the supply passage 10d to the pressurizing chamber 11. Fuel is supplied. The guide portion 30b stops its movement by colliding with the stopper 32 which is press-fitted into the housing (rod guide member 37) of the electromagnetic suction valve mechanism 300 and fixed. The rod 35 and the suction valve 30 are separate and independent structures. The suction valve 30 closes the flow path to the pressurizing chamber 11 by coming into contact with the valve seat 31a of the valve seat member 31 arranged on the suction side, and the flow path to the pressurizing chamber 11 by moving away from the valve seat 31a. Is configured to open.

When the plunger 2 moves in the direction (downward) of the cam 93 due to the rotation of the cam 93 in FIG. 1 and is in the suction stroke state, the volume of the pressurizing chamber 11 increases and the fuel pressure in the pressurizing chamber 11 increases. descend. When the electromagnetic coil 43 is turned off in this suction stroke, the sum of the urging force of the rod urging spring 40 and the fluid force due to the pressure of the suction passage 10d is larger than the fluid force due to the fuel pressure in the pressurizing chamber 11. As the size increases, the suction valve 30 is urged in the valve opening direction by the rod 35 to open the valve.

When the plunger 2 reaches the bottom dead center and finishes the inhalation process, the plunger 2 starts to move up. Here, the electromagnetic coil 43 remains in a non-energized state and no magnetic urging force acts on it. The volume of the pressurizing chamber 11 decreases with the compression movement of the plunger 2. In this state, the fuel once sucked into the pressurizing chamber 11 passes through the opening of the suction valve 30 in the opened state again. Since it is returned to 10d, the pressure in the pressurizing chamber 11 does not rise. This process is called the return process.

After that, by turning on the energization of the electromagnetic coil 43 at a desired timing, the magnetic attraction force is generated as described above, so that the rod 35 moves in the valve closing direction together with the movable core 36, and the tip portion 35b of the rod 35 Moves away from the suction valve 30. In this state, since the suction valve 30 is a check valve that opens and closes according to the differential pressure, the suction valve 30 is closed by the urging force of the suction valve urging spring 33. Since the plunger 2 is raised after the suction valve 30 is closed, the volume of the pressurizing chamber 11 is reduced and the fuel is pressurized. This is called a compression stroke. When the fuel in the pressurizing chamber 11 is pressurized and exceeds the total of the fuel pressure in the discharge valve chamber 12a and the urging force by the discharge valve spring 8c, the discharge valve 8b is opened and the fuel is discharged.

By controlling the energization timing of the electromagnetic suction valve mechanism 300 to the electromagnetic coil 43, the amount of high-pressure fuel discharged can be controlled. If the timing of energizing the electromagnetic coil 43 is advanced, the ratio of the return stroke in the compression stroke is small and the ratio of the discharge stroke is large. That is, less fuel is returned to the suction passage 10d, and more fuel is discharged to the common rail 23 at high pressure. On the other hand, if the energization timing is delayed, the ratio of the return stroke during the compression stroke is large and the ratio of the discharge stroke is small. That is, more fuel is returned to the suction passage 10d, and less fuel is discharged to the common rail 23 at high pressure. The energization timing of the electromagnetic coil 43 is controlled by a command from the ECU 27.

By controlling the energization timing of the electromagnetic coil 43 as described above, the amount of fuel discharged at high pressure can be controlled to the amount required by the internal combustion engine.
The low-pressure fuel chamber 10 is provided with a pressure pulsation reducing mechanism 9 that reduces the pressure pulsation generated in the fuel supply pump from spreading to the fuel pipe 28. Further, a damper upper portion 10b and a damper lower portion 10c are provided above and below the pressure pulsation reducing mechanism 9 at intervals, respectively. When the fuel once flowing into the pressurizing chamber 11 is returned to the suction passage 10d through the suction valve 30 in the opened state again for capacity control, the pressure pulsation in the low pressure fuel chamber 10 due to the fuel returned to the suction passage 10d. Occurs. However, the pressure pulsation reduction mechanism 9 provided in the low pressure fuel chamber 10 is formed by a metal diaphragm damper in which two corrugated disk-shaped metal plates are bonded together on the outer periphery thereof and an inert gas such as argon is injected therein. The pressure pulsation is absorbed and reduced by the expansion and contraction of this metal damper. Reference numeral 9a is a mounting bracket for fixing the metal damper to the inner peripheral portion of the pump body 1, and since it is installed on the fuel passage, the support portion with the damper is not the entire circumference but a part of the mounting bracket 9a. The fluid can move freely on the front and back.

The plunger 2 has a large diameter portion 2a and a small diameter portion 2b, and the volume of the sub chamber 7a increases or decreases due to the reciprocating motion of the plunger 2. The sub chamber 7a communicates with the low pressure fuel chamber 10 by a fuel passage 10e (see FIG. 3). When the plunger 2 is lowered, a fuel flow is generated from the sub chamber 7a to the low pressure fuel chamber 10, and when the plunger 2 is raised, a fuel flow is generated from the low pressure fuel chamber 10 to the sub chamber 7a.

As a result, it is possible to reduce the fuel flow rate inside and outside the pump during the suction stroke or the return stroke of the pump, and it has a function of reducing the pressure pulsation generated inside the fuel supply pump.

Further, the operation of the relief valve mechanism will be described in detail. As shown in FIG. 2, the relief valve mechanism 200 includes a seat member 201, a relief valve 202, a relief valve holder 203, a relief spring 204, and a relief spring stopper 205. The relief valve 202, the relief valve holder 203, and the relief spring 204 are inserted into the seat member 201 in this order, and the relief spring stopper 205 is fixed by press fitting or the like. The pressing force by the relief spring 204 is defined by the position of the relief spring stopper 205. The valve opening pressure of the relief valve 202 is set to a specified value by the pressing force of the relief spring 204. The relief valve mechanism 200 unitized in this way is fixed to the pump body 1 by press fitting or the like as shown in FIG. Although FIG. 1 shows a unitized relief valve mechanism 200, the present invention is not limited to this.

Since the fuel supply pump needs to pressurize the fuel to a very high pressure of several MPa to several tens of MPa, the set valve opening pressure of the relief valve 202 must be higher than that. When the set valve opening pressure is set to be equal to or lower than the set discharge pressure, the relief valve 202 opens even if the fuel is normally pressurized by the fuel supply pump. This malfunction of the relief valve 202 may lead to the occurrence of cavitation erosion in the vicinity of the seat portion of the seat member 201, a decrease in the discharge amount, a decrease in energy efficiency, and the like. The occurrence of cavitation erosion becomes more pronounced as the fuel pressure increases, so it is one of the most important issues when increasing the pressure.

From the above, it is necessary to set the set valve opening pressure of the relief valve 202 to be equal to or higher than the set discharge pressure. This leads to an increase in maximum pressure. Since the maximum pressure of the common rail 23 is the pressure obtained by adding the pressure loss of the relief valve 202 itself to the set valve opening pressure of the relief valve 202, the maximum pressure of the common rail 23 is increased while increasing the set valve opening pressure of the relief valve 202. In order to suppress the pressure loss, reduction of pressure loss is an important issue.

The present embodiment for solving these problems will be described with reference to FIG. The upper part of FIG. 6 shows a cross-sectional view of the relief valve mechanism 200 of this embodiment, and the lower part shows an enlarged cross-sectional view of the vicinity of the seat portion 201a surrounded by a frame line. In the vicinity of the seat portion 201a, the flow velocity is extremely high because the cross-sectional area of the flow path formed between the relief valve 202 and the seat member 201 is narrow. Therefore, if the shape is like a dash-dotted line that sharply bends the flow direction in the vicinity of this area, there is a concern that flow separation may occur and cavitation erosion may occur. In order to prevent this, if the shape is like a two-dot chain line that bends the flow at a place where the flow velocity is low, away from the seat portion 201a by a certain distance, cavitation erosion can be expected to be prevented, but the relief valve 202 is lifted. Even in such a case, since the distance between the relief valve 202 and the seat member 201 is short, there is a concern that a sufficient flow path cross-sectional area cannot be obtained and the pressure loss increases.

Therefore, in the relief valve mechanism 200 of the present embodiment, the relief valve 202, the seat portion 201a on which the relief valve 202 is seated are formed, the seat surface 201c inclined at the first angle AC with respect to the valve axis direction, and the seat portion 201a. A downstream inner diameter expanding portion 201d formed so as to be connected to the seat surface 201c on the downstream side and expanded radially outward from the seat surface 201c from the downstream end of the seat surface 201c, and a downstream inner diameter expanding portion 201d. A downstream end surface 201e formed radially outward from the downstream end of the portion 201d is provided. Further, the downstream inner diameter expanding portion 201d is formed by being connected to the seat surface 201c on the downstream side of the seat portion 201a, and is formed from the downstream end of the seat surface 201c on the second angle larger than the first angle AC with respect to the valve axis direction. It is formed so as to be inclined by AD. Further, the fourth angle DE in which the downstream end surface 201e is inclined with respect to the downstream inner diameter expanding portion 201d is formed to be larger than the third angle CD in which the downstream inner diameter expanding portion 201d is inclined with respect to the seat surface 201c. There is.

By doing so, the direction change of the flow becomes large as the flow velocity decreases away from the sheet portion 201a, so that the flow is less likely to separate and cavitation erosion can be expected to be prevented. At the same time, the distance between the relief valve 202 and the seat member 201 when the relief valve 202 is lifted by the downstream inner diameter expanding portion 201d is widened, and the pressure loss can be expected to be reduced by increasing the flow path cross-sectional area.

Up to this point, the case where the present invention is applied to the downstream of the seat portion 201a has been described, but the present invention can also be applied to the upstream of the seat portion 201a. Details will be described below with reference to FIG. 7.

In FIG. 7, a th-th. It is provided with an upstream inner diameter expanding portion 201b that is inclined at a five-angle AB. Further, the third angle CD in which the downstream inner diameter expanding portion 201d is inclined with respect to the seat surface 201c is formed so as to be smaller than the fifth angle AB. Further, the sixth angle BC on which the seat surface 201c is inclined with respect to the upstream inner diameter enlarged portion 201b is formed to be larger than the third angle CD.

By doing so, as the distance from the place where the flow direction changes to the sheet portion 201a increases, the direction change becomes larger, so that the flow is less likely to peel off and cavitation erosion is expected to be prevented. can. At the same time, the distance between the relief valve 202 and the seat member 201 when the relief valve 202 is lifted by the upstream inner diameter expanding portion 201a is widened, and the pressure loss can be expected to be reduced by increasing the flow path cross-sectional area. Further, as the sheet portion 201a approaches, the flow velocity increases and the pressure decreases.

On the other hand, when the shape is as shown by the alternate long and short dash line in FIG. 7, the pressure drops on the outer diameter side of A, and the actual pressure receiving diameter decreases with respect to the geometric sheet diameter, resulting in relief. The fluid force that opens the valve 202 may be reduced. This may reduce the lift amount of the relief valve 202 and cause an increase in pressure loss. However, in the above-described embodiment, the distance between the relief valve 202 and the seat member 201 is widened by the upstream inner diameter expanding portion 201b, and the flow path cross-sectional area is increased, so that the increase in the flow velocity can be moderated. As a result, the pressure drop toward the seat portion 201a can be moderated to prevent a substantial decrease in the pressure receiving diameter, which in turn can be expected to prevent an increase in pressure loss.

The connection point between the introduction passage 201f and the upstream inner diameter expanding portion 201b is point A, the connecting point between the upstream inner diameter expanding portion 201b and the seat surface 201c is point B, and the connecting point between the seat surface 201c and the downstream inner diameter expanding portion 201d is point C. In FIG. 7, the distance from the seat portion is longer in the order of point A, point B, and point C. Therefore, correspondingly, the change in the direction of the flow is the third angle CD <sixth angle BC <fifth angle AB. On the other hand, the distance from the seat portion to each point is not limited to this order, and it is desirable to change the magnitude relationship of each angle according to the distance, that is, to increase the angle as the distance increases.

A second embodiment of the present invention will be described with reference to FIG. In the relief valve mechanism 200, which is the object of the present invention, it is necessary to increase the valve opening pressure against the fuel pressure as described above, and therefore it is necessary to use a strong spring. Therefore, when the relief valve 202 is directly pressed by the spring seat at the end of the relief spring 204, there is a concern that the contact portion may be deformed or worn. In order to prevent this, the relief valve holder 203 is sandwiched between the two, and the relief valve 202 is pressed against the seat member 201 via the relief valve holder 203. In this case, the flow that has passed through the seat portion 201a needs to go around the relief valve holder 203 and flow to the outer periphery of the relief valve holder 203. In this embodiment, in addition to the shape of the seat portion 201a, the shape of the relief valve holder 203 provided at a position facing the seat portion 201a and the position with respect to the flow are defined to smoothly relieve the flow downstream of the seat portion 201a. It leads to the outer periphery of the valve holder 203.

In this embodiment, the relief valve 202 is formed in a ball shape, the relief valve 202 is held by the inner peripheral portion 203a, the relief valve holder 203 is provided to urge the seat portion 201a, and the relief valve holder 203 is on the downstream side. It has a holder bottom surface portion 203b arranged so as to face the end surface 201e. Further, as shown by a dotted line in the drawing, these surfaces are arranged so that the surface forming the holder bottom surface portion 203b intersects with the extension of the surface forming the downstream inner diameter enlarged portion 201d.

FIG. 9 shows a modified example of FIG. In FIG. 9, as shown by a dotted line in the figure, the holder bottom surface portion 203b is formed not only on the extension of the surface forming the downstream inner diameter enlarged portion 201d but also on the extension of the surface forming the seat surface 201c. These faces are arranged so that the faces intersect.

By doing so, the mainstream that has passed through the seat portion 201a can smoothly flow toward the outer periphery of the relief valve holder 203 through the gap formed between the downstream end surface 201e and the holder bottom surface portion 203a. Since the cross-sectional area of the flow path expands toward the outer circumference, the flow velocity is reduced, the flow can be prevented from peeling off, and cavitation erosion can be expected to be prevented. Further, since the mainstream that has passed through the seat portion 201a does not face the inner peripheral portion 203a side, cavitation bubbles enter the inner peripheral portion 203a and erosion occurs, and the direction change of the mainstream becomes large. It is expected that the increase in pressure loss can be prevented at the same time.

As described above, the fuel supply pump of the present embodiment includes the relief valve mechanism 200 described above, and the relief valve mechanism 200 is applied when the fuel in the discharge passage 12 on the downstream side of the discharge valve mechanism 8 exceeds the set pressure. It is configured to return fuel to the pressure chamber 11 or to a low pressure passage (low pressure fuel chamber 10 or suction passage 10d, etc.).

As described above, this embodiment can be applied not only to the relief valve mechanism 200 but also to functional parts for satisfying the performance of the fuel supply pump, for example, the electromagnetic suction valve mechanism 300 and the discharge valve mechanism 8. Yes, and it can also be applied to functional parts other than the above.

This is the end of the description of the examples, but the present invention can be widely modified and implemented without being limited to the above-described embodiment. For example, although the above embodiment applies the present invention to a fuel supply pump, it may be applied to a flood control device that requires a check valve. The arrangement position and arrangement method of the functional parts in the fuel supply pump are not limited to the examples of the above-described embodiment.

1 ... Pump body, 2 ... Plunger, 6 ... Cylinder, 7 ... Seal holder, 8 ... Discharge valve mechanism, 200 ... Relief valve mechanism, 201 ... Seat member, 201a ... Seat part, 201b ... Upstream inner diameter expansion part, 201c ... Seat surface, 201d ... Downstream inner diameter expansion part, 201e ... Downstream side end face, 201f ... Introduction passage, 202 ... Relief valve, 203 ... Relief valve holder, 203a ... Inner circumference, 203b ... Holder bottom surface, 204 ... Relief spring, 205 ... Spring holder, 300 ... Electromagnetic suction valve mechanism.

Claims (9)

A relief valve, a seat portion on which the relief valve is seated are formed, a seat surface inclined at a first angle with respect to the valve axis direction, and a seat surface connected to the seat surface on the downstream side of the seat portion, and the seat is formed. A downstream inner diameter expanding portion formed so as to expand radially outward from the downstream end of the surface, and a downstream end surface formed radially outward from the downstream end of the downstream inner diameter expanding portion. And upstream, which is formed by being connected to the upstream end of the seat surface on the upstream side of the seat portion and inclined from the downstream end of the introduction passage at a fifth angle smaller than the first angle with respect to the valve axis direction. With a side inner diameter enlargement part,
A plurality of connecting points including the introduction passage and the upstream inner diameter expanding portion, a connecting point between the upstream inner diameter expanding portion and the seat surface, and a connecting point between the seat surface and the downstream inner diameter expanding portion. A relief valve mechanism formed so that the angle of change in the direction of flow at each point increases as the distance from the seat portion to each point increases. In the relief valve mechanism according to claim 1, the downstream inner diameter expanding portion is formed so as to be connected to the seat surface on the downstream side of the seat portion, and is formed from the downstream end of the seat surface in the valve axis direction. A relief valve mechanism formed so as to incline at a second angle larger than the first angle. In the relief valve mechanism according to claim 1, the fourth angle at which the downstream end surface is inclined with respect to the downstream inner diameter expanding portion is set with respect to the third angle at which the downstream inner diameter expanding portion is inclined with respect to the seat surface. Relief valve mechanism formed to be large. The relief valve mechanism according to claim 1, wherein the relief valve mechanism is formed so that the third angle at which the downstream inner diameter expanding portion is inclined with respect to the seat surface is smaller than the fifth angle. The relief valve mechanism according to claim 3 , wherein the sixth angle at which the seat surface is inclined with respect to the upstream inner diameter enlarged portion is formed to be larger than the third angle. In the relief valve mechanism according to claim 1, the relief valve is formed in a ball shape, includes a relief valve holder that holds the relief valve at an inner peripheral portion and urges the seat portion, and the relief valve. The holder is a relief valve mechanism having a holder bottom surface portion arranged so as to face the downstream end surface. In the relief valve mechanism according to claim 6, these surfaces are arranged so that the surfaces forming the holder bottom surface intersect on the extension of the surface forming the downstream inner diameter expanding portion. .. The relief valve mechanism according to claim 7, wherein these surfaces are arranged so that the surfaces forming the holder bottom surface intersect on the extension of the surfaces forming the seat surface. A fuel supply pump provided with a discharge valve mechanism for discharging pressurized fuel in a pressurizing chamber includes the relief valve mechanism according to any one of claims 1 to 8, wherein the relief valve mechanism is the discharge valve mechanism. A fuel supply pump configured to return fuel to the pressurizing chamber or to the low pressure passage when the fuel in the discharge passage on the downstream side of the pump exceeds a set pressure.

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