JP6948906B2 - High pressure pump - Google Patents

Description

The present invention relates to a high pressure pump that discharges pressurized fuel through a fuel discharge valve.

A pressure-accumulation fuel supply system is known as a system for supplying fuel to an engine such as a diesel engine. The accumulator fuel supply system is provided with a fuel supply pump as an aspect of a high pressure pump. In the accumulator fuel supply system, the fuel pressurized by the fuel supply pump is supplied to the common rail to which the injector is connected, the fuel in the common rail is maintained at a high pressure, and fuel injection control by the injector is possible. .. The fuel supply pump introduces low-pressure fuel into the pressurizing chamber via an intake valve, pressurizes the fuel with a plunger, and then discharges the high-pressure fuel to the common rail side via a fuel discharge valve.

The fuel discharge valve is arranged in the middle of the fuel discharge flow path communicating with the pressurizing chamber. For example, as shown in Patent Document 1, the fuel discharge valve includes a valve piston held so as to be reciprocally reciprocating in the piston sliding hole in the axial direction, and a valve spring for urging the valve piston toward the seat portion. ing. The valve piston receives the fuel pressure in the pressurizing chamber, which acts in the direction opposite to the direction in which the urging force of the valve spring acts. When the urging force due to the fuel pressure in the pressurizing chamber is smaller than the sum of the urging force due to the fuel pressure on the valve spring side and the urging force due to the fuel pressure on the common rail side, the valve piston sits on the seat and the fuel discharge flow path is closed. Will be done. On the other hand, when the urging force due to the fuel pressure in the pressurizing chamber exceeds the sum of the urging force due to the fuel pressure on the valve spring side and the urging force due to the fuel pressure on the common rail side, the valve piston separates from the seat portion and the fuel discharge flow path becomes open. Be released.

Japanese Unexamined Patent Publication No. 2013-130114

Here, as the valve piston of the fuel discharge valve, a valve piston having an internal hole extending in the axial direction and opening on the end surface opposite to the sealing surface and an oil passage communicating the outer peripheral surface and the internal hole of the valve piston. There is. The internal holes and oil passages become part of the fuel discharge flow path when the valve is opened. 9 to 10 show an example of a conventional valve piston. FIG. 9 is a partial cross-sectional view of the conventional valve piston 100 as viewed from the radial direction, and FIG. 10 is a cross-sectional view of the I-I cross section of the valve piston 100 of FIG. 9 as viewed in the direction of an arrow.

The illustrated valve piston 100 has a sealing surface 105, a large diameter portion 103, and a small diameter portion 101. A small diameter portion 101 is provided on one end side of the valve piston 100 in the axial direction, and a large diameter portion 103 is provided on the other end side. The sealing surface 105 is formed at the end of the small diameter portion 101. The outer peripheral surface of the large diameter portion 103 is a sliding contact surface that is in sliding contact with the inner peripheral surface of the piston sliding hole (not shown).

Inside the valve piston 100, an internal hole 109 extending in the axial direction is provided over the small diameter portion 101 and the large diameter portion 103. The internal hole 109 is open to the end surface on the large diameter portion 103 side. Further, the valve piston 100 has an oil passage 107 that communicates the outer peripheral surface of the small diameter portion 101 with the internal hole 109. In the illustrated example of the valve piston 100, three oil passages 107 radially extending from the axial center P of the valve piston 100 are provided around the axis at equal intervals of 120 degrees. Further, the three oil passages 107 are provided so as to be inclined so that the opening position on the internal hole 109 side is closer to the large diameter portion 103 side (right side in FIG. 9) than the opening position on the small diameter portion 101 side.

The valve piston 100 is urged toward the small diameter portion 101 (left side in FIG. 9) by a valve spring (not shown) to block the fuel discharge flow path. On the other hand, when the fuel pressure in the pressurizing chamber rises, the valve piston 100 moves to the large diameter portion 103 side (right side in FIG. 9) due to the fuel pressure to open the fuel discharge flow path. When the fuel discharge flow path is opened, the high-pressure fuel in the pressurizing chamber flows from the outer periphery of the small diameter portion 101 into the internal hole 109 through the oil passage 107 and is discharged toward the common rail side.

The valve piston 100 reciprocates in the piston sliding hole in the axial direction to open and close the fuel discharge flow path. At that time, depending on the usage conditions, uneven wear may occur on the outer peripheral surface of the large diameter portion 103 that is in sliding contact with the inner peripheral surface of the piston sliding hole, which may hinder the opening / closing behavior of the fuel discharge valve. Specifically, when the valve piston 100 repeats sliding in the same phase, seizure or wear occurs on a part of the outer peripheral surface of the large diameter portion 103, the sliding resistance increases, and the valve piston 100 reciprocates. It may interfere. If the normal reciprocating operation of the valve piston 100 is hindered, the fuel flow rate discharged from the fuel supply pump will vary.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a high-pressure pump capable of reducing uneven wear of the valve piston of the fuel discharge valve and suppressing abnormalities in the opening and closing behavior of the fuel discharge valve. do.

In order to solve the above problems, according to a certain viewpoint of the present invention, in a high-pressure pump that discharges pressurized fuel through a fuel discharge valve, the fuel discharge valve is seated on a seat portion to provide a fuel discharge flow path. It includes a valve piston that opens and closes, and an urging member that urges the valve piston toward the seat portion. The valve piston has a sealing surface provided on one end side in the axial direction and an opening on the other end side in the axial direction. It has an internal hole and at least one oil passage that communicates the outer peripheral surface of the valve piston and the internal hole, and when the valve piston is viewed in the axial direction, the center line of the oil passage is the axial center of the valve piston. A high pressure pump that deviates from is provided.

As described above, according to the present invention, it is possible to reduce uneven wear of the valve piston of the fuel discharge valve and suppress abnormalities in the opening and closing behavior of the fuel discharge valve.

It is explanatory drawing which shows the structural example of the high pressure pump which concerns on embodiment of this invention. It is explanatory drawing which shows the structural example of the fuel discharge valve which concerns on the same embodiment. It is a side view which shows the structural example of the valve piston which concerns on the same embodiment. It is sectional drawing in the axial direction of the valve piston which concerns on the same embodiment. It is a figure for demonstrating the flow of fuel passing through the oil passage of the valve piston which concerns on this embodiment. It is a figure for demonstrating the flow of fuel passing through the oil passage of a conventional valve piston. It is explanatory drawing which shows the modification of the valve piston which concerns on this embodiment. It is explanatory drawing which shows another modification of the valve piston which concerns on the same embodiment. It is a side view which shows the structural example of the conventional valve piston. It is sectional drawing in the axial direction of the conventional valve piston.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.

(High pressure pump)
First, a configuration example of the fuel supply pump 5 according to the present embodiment will be described with reference to FIG. The fuel supply pump 5 is an aspect of a high pressure pump. FIG. 1 is a cross-sectional view showing a configuration example of the fuel supply pump 5.

The fuel supply pump 5 includes a pump housing 51, a feed pump 40, a cylinder head 53 having a fuel suction valve 55 and a fuel discharge valve 80, a camshaft 63 provided with a cam 65 on the outer periphery, and a tappet structure 70. And have. The fuel supply pump 5 is applied to, for example, an accumulator fuel injection system (common rail system) that injects fuel into a cylinder of a diesel engine.

The fuel supply pump 5 shown in FIG. 1 is a pump having one plunger 67 and one pressurizing chamber 59, but the number of the plunger 67 and the pressurizing chamber 59 is not particularly limited. The fuel supply pump may be a so-called row type pump in which a plurality of plungers and a pressurizing chamber are arranged in parallel, or a so-called radial type pump in which a plurality of plungers and a pressurizing chamber are arranged on the circumference. It may be a pump.

The pump housing 51 has a shaft support hole 51a and a flange support hole 51b. The shaft support hole 51a and the flange support hole 51b are formed coaxially in the axial direction continuously. The diameter of the flange support hole 51b is larger than the diameter of the shaft support hole 51a. The region between the shaft support hole 51a and the flange support hole 51b forms a cam chamber 51d. Further, the pump housing 51 has a tappet sliding hole 51c extending upward in the drawing from the cam chamber 51d.

The shaft support hole 51a rotatably supports one end side of the camshaft 63 via a bearing 58a. A flange member 61 is inserted and fixed in the flange support hole 51b. The flange member 61 has a shaft support hole 61a formed coaxially with the shaft support hole 51a of the pump housing 51. The shaft support hole 61a rotatably supports the other end side of the camshaft 63 via the bearing 58b. One end side of the camshaft 63 is supported by the shaft support hole 51a of the pump housing 51, and the other end side is supported by the shaft support hole 61a of the flange member 61.

The end of the camshaft 63 supported by the pump housing 51 on the flange member 61 side is inserted into an engine (not shown) and connected to the crankshaft of the engine via a gear (not shown). The end of the camshaft 63 on the opposite side is connected to the feed pump 40. The feed pump 40 may be, for example, a gear pump having a drive gear connected to the camshaft 63 via a coupling and a driven gear that meshes with the drive gear. The feed pump 40 sucks fuel from a fuel tank (not shown) as the camshaft 63 rotates, and supplies the fuel to the fuel suction valve 55 through a fuel passage (not shown). A flow rate control valve (not shown) for adjusting the flow rate of fuel introduced into the pressurizing chamber 59 is provided in the middle of the fuel passage.

A part of the cylinder head 53 is housed in the tappet sliding hole 51c of the pump housing 51. The cylinder head 53 includes a plunger sliding hole 53a extending on the same axis as the tappet sliding hole 51c and having an open lower end portion, and a pressurizing chamber 59 formed continuously in the axial direction from the plunger sliding hole 53a. Have. The plunger 67 is held in the plunger sliding hole 53a so as to be movable in the axial direction. The capacity of the pressurizing chamber 59 changes according to the axial position of the plunger 67.

The fuel intake valve 55 is provided facing the pressurizing chamber 59. The illustrated fuel intake valve 55 is a poppet valve in which the valve body moves to the pressurizing chamber 59 side and opens. For example, the fuel intake valve 55 opens when the pressure in the pressurizing chamber 59 becomes negative, and the low-pressure fuel supplied to the fuel gallery 53c is introduced into the pressurizing chamber 59. The fuel discharge valve 80 is provided so that one end faces the fuel discharge hole 53b that opens into the pressurizing chamber 59. The fuel discharge valve 80 opens when the pressure in the pressurizing chamber 59 becomes equal to or higher than a predetermined pressure, and discharges high-pressure fuel toward the common rail.

The tappet structure 70 is provided between the lower end of the plunger 67 and the cam 65. The tappet structure 70 is provided so as to be able to reciprocate in the tappet sliding hole 51c of the pump housing 51 in the axial direction. The tappet structure 70 reciprocates the tappet sliding hole 51c with the rotation of the cam 65, converts the rotational motion of the cam 65 into a linear motion, and reciprocates the plunger 67. The tappet sliding hole 51c houses a tappet spring 75 whose one end is supported by the cylinder head 53 and the other end is supported by the tappet structure 70. The tappet spring 75 constantly urges the tappet structure 70 toward the cam 65 side.

The tappet structure 70 includes a tappet body 71 and a tappet roller 73. The tappet body 71 has a cylindrical outer shape that can slide in the tappet sliding hole 51c. The tappet body 71 has a recess 73a opened on the cylinder head 53 side and a roller holding portion 73b opened on the cam 65 side. The lower end of the plunger 67 is in contact with the bottom surface of the recess 73a. A spring seat 77 is provided on the bottom surface of the recess 73a, and the tappet body 71 supports the lower end of the tappet spring 75 via the spring seat 77.

The tappet roller 73 is rotatably held by the roller holding portion 73b. The roller holding portion 73b has a curved surface portion having a shape corresponding to the outer peripheral surface of the tappet roller 73, and makes the outer peripheral surface of the tappet roller 73 slidable to hold the tappet roller 73. The tappet roller 73 comes into contact with the cam 65, and the frictional force between the cam 65 and the tappet roller 73 causes the tappet roller 73 to rotate about the axis as the cam 65 rotates. The illustrated tappet structure 70 has a structure in which the tappet roller 73 is held by the tappet body 71 without using the roller support pin, but the tappet roller 73 is held by the tappet body 71 by using the roller support pin. It may be a structure to make it.

The tappet structure 70 is lifted against the urging force of the tappet spring 75 until the contact point of the tappet roller 73 with respect to the cam 65 reaches the top of the cam ridge. As a result, the plunger 67 is lifted. Further, the tappet structure 70 is lifted down by the urging force of the tappet spring 75 after the contact point of the tappet roller 73 with respect to the cam 65 exceeds the top of the cam ridge. As a result, the plunger 67 is lifted down. In this way, the plunger 67 lifts and lifts down as the cam 65 rotates.

The operation of the fuel supply pump 5 shown in FIG. 1 will be briefly described. When the camshaft 63 rotates with the rotation of the crankshaft of an engine (not shown), the feed pump 40 connected to the camshaft 63 is driven. The feed pump 40 sucks fuel from a fuel tank (not shown) and sends it to the flow control valve. The flow control valve regulates the fuel flow rate and supplies low-pressure fuel to the fuel gallery 53c. Further, when the cam 65 rotates with the rotation of the cam shaft 63, the rotary motion of the cam 65 is converted into a linear motion by the tappet structure 70 and transmitted to the plunger 67, and the plunger 67 moves in the plunger sliding hole 53a. It moves back and forth.

For example, when the plunger 67 starts lift-down from top dead center, the fuel intake valve 55 and the fuel discharge valve 80 are closed. When the pressure in the pressurizing chamber 59 decreases and the pressure in the pressurizing chamber 59 becomes negative as the plunger 67 lifts down, the fuel suction valve 55 opens and the fuel in the fuel gallery 53c is pressurized. It is introduced in the room 59. When the plunger 67 starts the lift after reaching bottom dead center, the fuel intake valve 55 and the fuel discharge valve 80 are closed. When the pressure in the pressurizing chamber 59 rises with the lifting of the plunger 67, the fuel discharge valve 80 opens and the high-pressure fuel is discharged toward a common rail (not shown).

(Fuel discharge valve)
Next, the fuel discharge valve 80 of the fuel supply pump 5 according to the present embodiment will be described in detail. FIG. 2 is a diagram for explaining a configuration example of the fuel discharge valve 80, and is a cross-sectional view showing an enlarged portion of a region X in FIG.

The fuel discharge valve 80 is arranged in the piston sliding hole 53d provided in the cylinder head 53. The fuel discharge valve 80 includes a valve piston 81, a valve spring 91, and a spring receiving member 93. The piston sliding hole 53d is provided so as to communicate coaxially with the fuel discharge hole 53b connected to the pressurizing chamber 59 (not shown). The diameter of the piston sliding hole 53d is larger than the diameter of the fuel discharge hole 53b, and a step serving as a seat portion 99 is formed at the boundary between the fuel discharge hole 53b and the piston sliding hole 53d.

The valve piston 81 is provided so as to be able to reciprocate in the piston sliding hole 53d in the axial direction. The valve piston 81 has a sealing surface 85 on one end side, and the sealing surface 85 can come into contact with the seat portion 99. The valve piston 81 is urged toward the seat portion 99 by the valve spring 91. The valve spring 91 is arranged in a compressed state between the valve piston 81 and the spring receiving member 93. Specifically, one end side of the valve spring 91 abuts on the stepped portion of the internal hole 89 of the valve piston 81, and the other end side is the inner peripheral protrusion 93a provided in the middle of the internal hole 94 of the spring receiving member 93. Is in contact with. The spring receiving member 93 is fixed by being press-fitted into the piston sliding hole 53d, and the valve piston 81 is constantly urged toward the seat portion 99 by the valve spring 91 arranged in the compressed state.

The valve piston 81 is urged toward the seat portion 99 by the urging force of the valve spring 91 and the pressure in the piston sliding hole 53d. Further, the valve piston 81 is urged to the side opposite to the seat portion 99 side by the pressure in the fuel discharge hole 53b communicating with the pressurizing chamber (not shown). The axial position of the valve piston 81 is determined by the balance between the urging force due to the pressure in the fuel discharge hole 53b, the urging force of the valve spring 91, and the urging force due to the pressure in the piston sliding hole 53d.

While the fuel pressure in the pressurizing chamber is low, the sum of the urging force of the valve spring 91 and the urging force due to the pressure in the piston sliding hole 53d exceeds the urging force due to the pressure in the fuel discharge hole 53b, and the valve piston 81 moves. Seated on the seat 99, the fuel discharge valve 80 is closed. When the fuel in the pressurizing chamber is pressurized and the urging force due to the pressure in the fuel discharge hole 53b exceeds the sum of the urging force due to the pressure in the valve spring 91 and the pressure in the piston sliding hole 53d, the valve piston The 81 is separated from the seat portion 99, and the fuel discharge valve 80 is opened.

When the fuel discharge valve 80 is opened, the high-pressure fuel in the fuel discharge hole 53b flows into the piston sliding hole 53d through between the seal surface 85 of the valve piston 81 and the seat portion 99. The high-pressure fuel that has flowed into the piston sliding hole 53d flows into the internal hole 89 through the oil passage 87 of the valve piston 81, and is further discharged to the common rail side through the internal hole 94 of the spring receiving member 93. In this way, the valve piston 81 reciprocates in the piston sliding hole 53d in the axial direction in response to the reciprocating movement of the plunger 67 when the fuel supply pump 5 is driven, and the fuel discharge valve 80 opens and closes.

(Example of valve piston configuration)
Next, the valve piston 81 constituting the fuel discharge valve 80 of the fuel supply pump 5 according to the present embodiment will be described. 3 and 4 are explanatory views showing a configuration example of the valve piston 81. FIG. 3 is a partial cross-sectional view of the valve piston 81 viewed from the radial direction, and FIG. 4 is a cross-sectional view of the II-II cross section of FIG. 3 viewed in the arrow direction.

The valve piston 81 has a sealing surface 85, a large diameter portion 83, and a small diameter portion 82. A small diameter portion 82 is provided on one end side of the valve piston 81 in the axial direction, and a large diameter portion 83 is provided on the other end side. The sealing surface 85 is formed at the end of the small diameter portion 82. The outer peripheral surface of the large diameter portion 83 is a sliding contact surface that is in sliding contact with the inner peripheral surface of the piston sliding hole 53d.

Inside the valve piston 81, an internal hole 89 extending in the axial direction is provided over the small diameter portion 82 and the large diameter portion 83. The internal hole 89 is open to the end surface on the large diameter portion 83 side. Further, the valve piston 81 has an oil passage 87 that communicates the outer peripheral surface of the small diameter portion 82 with the internal hole 89. In the illustrated example of the valve piston 81, three oil passages 87 extending radially from the axial center P of the valve piston 81 are provided around the axis at equal intervals of 120 degrees. Further, the three oil passages 87 are provided so as to be inclined so that the opening position on the inner hole 89 side is on the large diameter portion 83 side (right side in FIG. 3) with respect to the opening position on the outer peripheral surface side of the small diameter portion 82. ing.

As shown in FIG. 4, the three oil passages 87 are provided so that the center line C1 of the oil passage 87 is deviated from the axial center P of the valve piston 81 when the valve piston 81 is viewed in the axial direction. The three oil passages 87 shown in FIG. 4 are provided so that their center lines C1 are all shifted in the same counterclockwise direction with respect to the axis P. By providing the oil passage 87 in this way, it is possible to apply an axial turning force to the valve piston 81 when the high-pressure fuel passes through the oil passage 87.

FIG. 5 is an explanatory diagram showing a flow of fuel passing through the oil passage 87. Since the center line C1 of the oil passage 87 is deviated from the axis P, the fuel (broken line arrow) flowing from the outer peripheral surface side of the small diameter portion 82 toward the inner hole 89 is discharged from the inner peripheral surface of the oil passage 87. It passes through the oil passage 87 while colliding with the inner peripheral surface 87a on the region side including the axis P from the center line C1 of the oil passage 87. Therefore, a clockwise turning force is applied to the valve piston 81, and the valve piston 81 can be reciprocated in the piston sliding hole 53d while rotating around the axis. As a result, uneven wear of the valve piston 81 can be reduced, and abnormalities in the opening / closing behavior of the fuel discharge valve 80 can be suppressed.

For reference, the flow of fuel through the oil passage of a conventional valve piston will be described. FIG. 6 is an explanatory view showing the flow of fuel passing through the oil passage 107 of the conventional valve piston, and corresponds to the axial cross-sectional view of the valve piston 100 shown in FIG. The illustrated oil passage 107 of the valve piston is formed radially from the axis P so that its center line overlaps the axis P of the valve piston. Therefore, all the fuel (broken line arrow) that flows from the outer peripheral surface side of the small diameter portion 101 into the internal hole 109 through the oil passage 107 flows toward the axis P. In FIG. 6, the oil passage 107 appears to have a reduced diameter toward the internal hole 109 because the oil passage 107 is formed so as to be inclined toward the large diameter portion 103. Since the diameter of the oil passage 107 does not actually change, the turning force of the valve piston is not generated when the fuel flowing through the oil passage 107 collides with the inner peripheral surface of the oil passage 107.

In the fuel supply pump 5 according to the present embodiment, the amount of deviation of the center line C1 of the oil passage 87 from the axis P of the valve piston 81 may be designed within an appropriate range. The larger the deviation amount, the larger the turning force that can be generated in the valve piston 81 when the fuel passes through the oil passage 87. However, if the amount of displacement is too large, the adjacent oil passages 87 may be connected to each other, making it difficult to smoothly flow the fuel into the internal holes 89. Therefore, of the inner peripheral surfaces of the oil passage 87, the inner peripheral surface 87b on the region side of the center line C1 of the oil passage 87 that does not include the axial center P extends in the tangential direction of the inner hole 89. It is preferable to shift the center line C1 of (see FIG. 4).

Further, in order to increase the turning force generated in the valve piston 81, at least one of the inner peripheral surfaces of the oil passage 87 on the region side including the axis P from the center line C1 of the oil passage 87. The portion may be treated to increase resistance to the flow of fuel. By increasing the resistance of the flow of fuel flowing along the inner peripheral surface 87a, the turning force of the valve piston 81 generated when the fuel collides with the inner peripheral surface 87a can be increased.

FIG. 7 shows a configuration example in which the resistance increasing portion 88 is formed on the inner peripheral surface 87a of the oil passage 87 to increase the resistance to the flow of fuel. The resistance increasing portion 88 may be, for example, a stepped portion provided with at least one step. Each step forming the stepped portion may be formed along a direction intersecting the flow of fuel flowing through the oil passage 87. Since the inner peripheral surface 87a of the oil passage 87 has such a stepped portion, the force that pushes the valve piston 81 clockwise generated when the fuel collides with the step becomes a turning force, and the valve piston 81 has a turning force. The turning force can be increased.

Further, the resistance increasing portion 88 may be a roughened surface finish having a roughened surface. The rough surface finish may have linear or point-like scratches or irregularities formed on the surface of the inner peripheral surface 87a of the oil passage 87 by an appropriate method. When the inner peripheral surface 87a of the oil passage 87 has such a rough surface finish, the resistance to the flow of fuel flowing along the inner peripheral surface 87a is increased, and the turning force of the valve piston 81 can be increased. ..

Further, in order to increase the turning force generated in the valve piston 81, of the edges of the oil passage 87 opened on the outer peripheral surface of the small diameter portion 82, the region side of the center line C1 of the oil passage 87 does not include the axial center P. An R surface may be provided on at least a part of the edge of the. FIG. 8 shows a configuration example in which the R surface is provided on the edge 87c on the inner peripheral surface 87b side of the oil passage 87. By providing the R surface on the edge 87c, fuel easily flows into the oil passage 87 even when the valve piston 81 is turning, and the valve piston utilizing the collision force of the fuel with respect to the inner peripheral surface 87a of the oil passage 87. It is possible to easily generate the turning force of 81.

As described above, the fuel discharge valve 80 of the fuel supply pump 5 according to the present embodiment is a valve piston in which the center line C1 of the oil passage 87 when viewed in the axial direction is deviated from the axial center P of the valve piston 81. Has 81. Therefore, when the fuel discharge valve 80 is opened, the fuel passing through the oil passage 87 collides with the inner peripheral surface 87a of the oil passage 87, so that a turning force is generated in the valve piston 81, and the valve piston 81 reciprocates while turning. Can be moved. As a result, uneven wear of the valve piston 81 can be reduced, and abnormalities in the opening / closing behavior of the fuel discharge valve 80 can be suppressed.

Further, of the inner peripheral surface of the oil passage 87 of the valve piston 81, the resistance increasing portion 88 is formed on at least a part of the inner peripheral surface 87a on the region side including the axial center P of the valve piston 81 with respect to the center line C1 of the oil passage 87. By having the above, the turning force generated by the collision of the fuel can be made larger. As a result, uneven wear of the valve piston 81 can be reduced, and the certainty of suppressing abnormalities in the opening / closing behavior of the fuel discharge valve 80 can be increased.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or modifications within the scope of the technical ideas described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

Further, in the above embodiment, the high pressure pump is a fuel supply pump provided in the common rail system, but the present invention is not limited to such an example. As long as it is a high-pressure pump that pressurizes and pumps fuel, it may be a pump other than the fuel supply pump provided in the common rail system.

5 ... Fuel supply pump, 51 ... Pump housing, 53 ... Cylinder head, 53b ... Fuel discharge hole, 53d ... Piston sliding hole, 59 ... Pressurizing chamber, 80 ... -Fuel discharge valve, 81 ... valve piston, 82 ... small diameter part, 83 ... large diameter part, 85 ... seal surface, 87 ... oil passage, 87a, 87b ... inner peripheral surface , 88 ... Resistance increase part, 89 ... Internal hole, 91 ... Valve spring, 99 ... Seat part

Claims (2)

In a high-pressure pump that discharges pressurized fuel through a fuel discharge valve
The fuel discharge valve is
It is provided with a valve piston that sits on the seat and opens and closes the fuel discharge flow path, and an urging member that urges the valve piston toward the seat.
The valve piston has at least one oil passage that communicates a sealing surface provided on one end side in the axial direction, an internal hole opened on the other end side in the axial direction, and an outer peripheral surface of the valve piston and the internal hole. And have
When the valve piston is viewed in the axial direction, the center line of the oil passage is deviated from the axial center of the valve piston, and the valve is located on the inner peripheral surface of the oil passage with respect to the center line of the oil passage. A resistance increasing portion is provided on at least a part of the inner peripheral surface on the region side including the axis of the piston.
The resistance increasing portion is a high-pressure pump which is a stepped portion or a rough surface finish. When the valve piston is viewed in the axial direction, the edge of the oil passage that opens on the outer peripheral surface of the valve piston is on the region side of the center line of the oil passage that does not include the axial center of the valve piston. The high-pressure pump according to claim 1 , which has an R-plane on at least a part of an edge.

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