JP6596304B2 - High pressure fuel supply pump - Google Patents

Description

  The present invention relates to a high-pressure fuel supply pump that supplies fuel to an engine at a high pressure, and more particularly to a discharge valve mechanism.

  As a background art of this technical field, there is JP-A-2015-86699 (Patent Document 1). According to paragraph 0016 of this publication, “a cylindrical hole 60H is provided from the peripheral wall of the pump body 1 toward the pressurizing chamber 12 at a position facing the cylindrical hole 200H across the pressurizing chamber 12. A discharge valve unit 60 is mounted on the cylindrical hole 60H, and a valve seat (valve seat) 61 is formed at the tip of the discharge valve unit 60, and a valve having a through hole 11A serving as a discharge passage at the center. A seat member (valve seat member) 61B is provided, and a valve holder 62 surrounding the periphery of the valve seat 61 is fixed to the outer periphery of the valve seat member 61B. A spring 64 is provided for urging the valve 63 in a direction to press the valve seat 61. A non-pressurizing chamber side opening of the cylindrical hole 60H is fixed to the pump body 1 by screw fastening. DOO 11 is provided. "Is described as.

JP2015-86699A

The prior art has the following problems.
The discharge valve of the high-pressure fuel supply pump has the function of a check valve for pressure-feeding the fuel pressurized in the ascending process of the plunger in the pressurizing chamber to the common rail, and is press-fitted to the pump body. And a valve body seated on the discharge valve seat.
In the state where the discharge valve seat is press-fitted and coupled, the seat surface of the discharge valve seat on which the valve element is seated is greatly deformed, resulting in a phenomenon that the sealing performance deteriorates.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a discharge valve mechanism that has a good sealing property by reducing deformation of a seat surface that occurs when a discharge valve seat is press-fitted in a high-pressure fuel supply pump.

In order to solve the above problems, the present invention includes a pressurizing chamber, a valve body provided on the discharge side of the pressurizing chamber, and a discharge valve seat on which the valve body is seated, and the discharge valve seat In the high-pressure fuel supply pump, which includes a press-fit portion for press-fitting to the body and a seat surface that contacts the valve body, the outer diameter of the press-fit portion extends from the seat surface to the press-fit portion in the press-fit direction. rather smaller than the outer diameter in the region formed, and to and smaller than the diameter of the seat surface.

According to the present invention, it is possible to reduce deformation of the seat surface that occurs when the discharge valve seat is press-fitted and joined.
Other configurations, operations, and effects of the present invention will be described in detail in the following examples.

1 is a configuration diagram of an engine system to which a high-pressure fuel supply pump is applied. It is a longitudinal cross-sectional view of a high pressure fuel supply pump. It is horizontal direction sectional drawing seen from the upper direction of a high pressure fuel supply pump. It is the longitudinal cross-sectional view seen from FIG. 2 of the high-pressure fuel supply pump. The horizontal direction sectional view of an example of the discharge valve mechanism of a high-pressure fuel supply pump is shown. FIG. 3 is a horizontal cross-sectional view showing the discharge valve mechanism 8 of the first embodiment. It is a horizontal direction sectional view showing discharge valve mechanism 8 of Example 2. It is a horizontal direction sectional view showing discharge valve mechanism 8 of Example 3. It is a horizontal direction sectional view showing discharge valve mechanism 8 of Example 4.

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

First, a first embodiment of the present invention will be described in detail with reference to the drawings.

  The configuration and operation of the system will be described with reference to the overall configuration diagram of the engine system shown in FIG. The portion surrounded by the broken line indicates the main body of the high-pressure fuel supply pump (hereinafter referred to as the high-pressure fuel supply pump), and the mechanisms and parts shown in the broken line are integrated into the pump body 1. Indicates.

  The fuel in the fuel tank 20 is pumped up by the feed pump 21 based on a signal from an engine control unit 27 (hereinafter referred to as ECU). This fuel is pressurized to an appropriate feed pressure and sent to the low-pressure fuel inlet 10a of the high-pressure 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 constituting the variable capacity mechanism via the pressure pulsation reducing 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 reciprocating power is applied to the plunger 2 by the cam mechanism 93 of the engine. The reciprocating motion of the plunger 2 sucks fuel from the suction valve 30 during the downward stroke of the plunger 2 and pressurizes the fuel during the upward stroke. Through the discharge valve mechanism 8, the fuel is pumped to the common rail 23 to which the pressure sensor 26 is attached. The injector 24 injects fuel into the engine based on a signal from the ECU 27. This embodiment is a high-pressure fuel supply pump applied to a so-called direct injection engine system in which an injector 24 directly injects fuel into a cylinder cylinder of an engine.

  The high-pressure fuel supply pump discharges the fuel flow rate of the desired supply fuel by a signal from the ECU 27 to the electromagnetic suction valve mechanism 300.

  FIG. 2 is a longitudinal sectional view of the high-pressure fuel supply pump of this embodiment, and FIG. 3 is a horizontal sectional view of the high-pressure fuel supply pump as seen from above. FIG. 4 is a longitudinal sectional view of the high-pressure fuel supply pump as seen from a different direction from FIG. FIG. 5 is a cross-sectional view of an example of the discharge valve mechanism 8.

  The high-pressure fuel supply pump of the present embodiment uses a mounting flange 1e provided in the pump body 1 to be in close contact with the high-pressure fuel supply pump mounting portion 90 of the internal combustion engine and is fixed with a plurality of bolts.

  An O-ring 61 is fitted into the pump body 1 for sealing between the high-pressure fuel supply pump mounting portion 90 and the pump body 1 to prevent the engine oil from leaking to the outside.

  A cylinder 6 that guides the reciprocating motion of the plunger 2 and forms a pressurizing chamber 11 together with the pump body 1 is attached to the pump body 1. An electromagnetic suction valve mechanism 300 for supplying fuel to the pressurizing chamber 11 and a discharge valve mechanism 8 for discharging fuel from the pressurizing chamber 11 to the discharge passage are provided.

  The cylinder 6 is press-fitted with the pump body 1 on the outer peripheral side thereof, and further, at the fixed portion 6a, the body is deformed to the inner week side to press the cylinder upward in the figure, and the cylinder 6 is brought into the pressure chamber 11 at the upper end surface. The pressurized fuel is sealed so that it does not leak to the low pressure side. That is, the pressurizing chamber 11 includes the pump body 1, the electromagnetic suction valve mechanism 300, the plunger 2, the cylinder 6, and the discharge valve mechanism 8.

  At the lower end of the plunger 2 is provided a tappet 92 that converts the rotational motion of the cam 93 attached to the camshaft of the internal combustion engine into vertical motion and transmits it to the plunger 2. The plunger 2 is pressure-bonded to the tappet 92 by the spring 4 through the retainer 15. Thereby, the plunger 2 can be reciprocated up and down with the rotational movement of the cam 93.

  A plunger seal 13 held at the lower end of the inner periphery of the seal holder 7 is installed in a slidable contact with the outer periphery of the plunger 2 at the lower part of the cylinder 6 in the figure. Thereby, 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, lubricating oil (including engine oil) for lubricating the sliding portion in the internal combustion engine is prevented from flowing into the pump body 1.

  A suction joint 51 is attached to the side surface of the pump body 1 of the high-pressure fuel supply pump. 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 is supplied from here to the inside of the high-pressure fuel supply pump. The suction filter 52 in the suction joint 51 serves to prevent foreign matter existing between the fuel tank 20 and the low-pressure fuel inlet 10a from being absorbed into the high-pressure fuel supply pump by the flow of fuel.

  The fuel that has passed through the low-pressure fuel intake port 10a reaches the intake port 31b of the electromagnetic intake valve mechanism 300 via the pressure pulsation reducing mechanism 9 and the low-pressure fuel flow path 10d.

  When the plunger 2 moves in the direction of the cam 93 due to the rotation of the cam 93 and is in the suction stroke state, the volume of the pressurizing chamber 11 increases and the fuel pressure in the pressurizing chamber 11 decreases. In this process, when the fuel pressure in the pressurizing chamber 11 becomes lower than the pressure in the suction port 31b, the suction valve 30 is opened. The fuel flows through the opening 30 e of the intake valve 30 and flows into the pressurizing chamber 11.

  After the plunger 2 completes the suction stroke, the plunger 2 starts to move upward and moves to the compression stroke. Here, the electromagnetic coil 43 remains in a non-energized state and no magnetic biasing force acts. The rod biasing spring 40 is set to have a biasing force necessary and sufficient to keep the suction valve 30 open in a non-energized state. 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 is again sucked through the opening 30 e of the intake valve 30 in the valve open state. Since the pressure is returned to the passage 10d, the pressure in the pressurizing chamber does not increase. This process is called a return process.

  In this state, when a control signal from the engine control unit 27 (hereinafter referred to as ECU) is applied to the electromagnetic intake valve mechanism 300, a current flows through the electromagnetic coil 43 via the terminal 46. Then, the magnetic biasing force overcomes the biasing force of the rod biasing spring 40 and the rod 35 moves away from the suction valve 30. Therefore, the suction valve 30 is closed by the biasing force by the suction valve biasing spring 33 and the fluid force caused by the fuel flowing into the suction passage 10d. After the valve is closed, the fuel pressure in the pressurizing chamber 11 rises with the upward movement of the plunger 2, and when the pressure exceeds the pressure at the fuel discharge port 12, high-pressure fuel is discharged via the discharge valve mechanism 8 to the common rail 23. Supplied. This stroke is called a discharge stroke.

  That is, the compression stroke of the plunger 2 (the upward stroke from the lower start point to the upper start point) includes a return stroke and a discharge stroke. And the quantity of the high pressure fuel discharged can be controlled by controlling the energization timing to the coil 43 of the electromagnetic suction valve mechanism 300. If the timing of energizing the electromagnetic coil 43 is advanced, the ratio of the return stroke during the compression stroke is small and the ratio of the discharge stroke is large. That is, the amount of fuel returned to the suction passage 10d is small and the amount of fuel discharged at high pressure is large. 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, the amount of fuel returned to the suction passage 10d is large, and the amount of fuel discharged at high pressure is small. The energization timing to the electromagnetic coil 43 is controlled by a command from the ECU 27.

By controlling the energization timing to the electromagnetic coil 43 as described above, the amount of fuel discharged at high pressure can be controlled to an amount required by the internal combustion engine.

  The low pressure fuel chamber 10 is provided with a pressure pulsation reduction mechanism 9 that reduces and reduces the pressure pulsation generated in the high pressure fuel supply pump from spreading to the fuel pipe 28. When the fuel that has once flowed into the pressurizing chamber 11 is returned to the suction passage 10d through the intake valve body 30 that is opened again for capacity control, the fuel returned to the suction passage 10d causes the pressure in the low-pressure fuel chamber 10 to be reduced. Pulsation occurs. However, the pressure pulsation reducing mechanism 9 provided in the low-pressure fuel chamber 10 is formed of a metal diaphragm damper in which two corrugated disk-shaped metal plates are bonded together on the outer periphery and an inert gas such as argon is injected inside. The pressure pulsation is absorbed and reduced by expansion and contraction of the metal damper.

  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 as the plunger reciprocates. The sub chamber 7a communicates with the low pressure fuel chamber 10 through a fuel passage 10e. When the plunger 2 descends, fuel flows from the sub chamber 7a to the low pressure fuel chamber 10, and when it rises, fuel flows from the low pressure fuel chamber 10 to the sub chamber 7a.

  As a result, the flow rate of fuel into and out of the pump during the suction stroke or return stroke of the pump can be reduced, and the pressure pulsation generated inside the high-pressure fuel supply pump can be reduced.

  FIG. 5 is a horizontal sectional view showing an example of the discharge valve mechanism 8. The discharge valve mechanism 8 is provided at the outlet of the pressurizing chamber 11, and includes a discharge valve sheet 8a, a valve body 8b that contacts and separates from the discharge valve sheet 8a, and an elastic member that biases the valve body 8b toward the discharge valve sheet 8a. 8c and a discharge valve stopper 8d that determines the stroke (movement distance) of the valve body 8b. Specifically, the discharge valve seat 8 a is integrally provided with a seat surface 8 f on which the valve body 8 b is seated and a press-fit portion 8 g that is press-fitted into the pump body 1. The discharge valve stopper 8d and the pump body 1 are joined by welding at the contact portion 8e to block the fuel and the outside. The elastic member 8c and the valve body 8b are disposed on the discharge passage 12 side with respect to the pressurizing chamber 11 with reference to the discharge valve seat 8a.

  In a state where there is no fuel differential pressure in the pressurizing chamber 11 and the discharge valve chamber 12a, the valve body 8b is pressed against the discharge valve seat 8a by the urging force of the elastic member 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, the valve body 8b opens against the elastic member 8c. The high-pressure fuel in the pressurizing chamber 11 is discharged to the common rail 23 through the discharge valve chamber 12a, the fuel discharge passage 12b, and the fuel discharge port 12. When the valve body 8b is opened, it comes into contact with the discharge valve stopper 8d, and the stroke is limited. Therefore, the stroke of the valve body 8b is appropriately determined by the discharge valve stopper 8d. As a result, it is possible to prevent the fuel that has been discharged at high pressure into the discharge valve chamber 12a from flowing back into the pressurizing chamber 11 again due to a delay in closing the valve body 8b due to the stroke being too large, and the efficiency of the high-pressure fuel supply pump Reduction can be suppressed. Further, when the valve body 8b repeats opening and closing movements, the outer periphery of the discharge valve stopper 8d is guided so that the valve body 8b moves only in the stroke direction. By doing so, the discharge valve mechanism 8 becomes a check valve that restricts the flow direction of fuel.

  Here, when the discharge valve seat 8a is press-fitted to the pump body 1, the seat surface 8f on which the valve body is seated is greatly deformed, resulting in a phenomenon that the sealing performance is deteriorated.

  Here, when the outer diameter of the seat surface 8f is equal to or larger than the outer diameter of the press-fit portion that is press-fitted into the pump body 1, the deformation of the press-fit portion 8g directly affects the seat portion 8f of the discharge valve seat 8a. Therefore, when the discharge valve seat 8a is press-fitted and coupled to the pump body 1, the deformation of the seat surface 8f is large. This hinders the valve body 8b from sealing against the seat surface 8f, resulting in a deterioration in sealing performance.

  Therefore, in the following, a high pressure fuel supply pump having a discharge valve mechanism 8 that reduces deformation of the seat surface 8f of the discharge valve seat 8a when press-fitting is described with reference to FIG. FIG. 6 is a horizontal sectional view showing the discharge valve mechanism 8 of the first embodiment. Here, the same reference numerals as those in FIG. Note that the pump body 1 referred to here is configured to be press-fitted into the discharge valve seat 8a, but the pump body 1 is assembled as a unitized discharge valve mechanism 8 by press-fitting the discharge valve seat 8a into another member. It may be inserted into. Further, in the present embodiment, the valve body 8b has a poppet valve shape, but the type of the valve body is not limited. In the discharge valve mechanism 8 of the present embodiment, the outer diameter of the press-fit portion 8g is smaller than the outer diameter of the seat surface 8f. The outer diameter of the discharge valve seat a in the region formed in the press-fitting direction from the seat surface 8f to the press-fitting part 8g is also smaller than the press-fitting part 8g. In this embodiment, this region is a sheet portion 8i. As the outer diameter of the press-fit portion 8g is reduced, the rigidity of the press-fit portion 8g is lower than the rigidity of the seat portion 8i. Therefore, it is possible to reduce deformation of the seat surface 8f that occurs when the discharge valve seat 8a is press-fitted to the pump body 1, and as a result, the sealing performance is improved. Further, the press-fitting portion 8g of the discharge valve seat 8a has a sealing function like the seat surface 8f. Even when the valve body 8b is in contact with the seat surface 8f of the discharge valve seat 8a, there is a concern that the fuel slightly flows into the discharge valve chamber 12a from the press-fit portion 8g. However, since the outer diameter of the press-fit portion 8g is smaller than the outer diameter of the seat surface 8f, it is possible to reduce the risk of fuel leakage from the press-fit portion 8g.

  This embodiment is also useful in the pump assembly process. When the inner diameter of the sheet surface 8f is larger than the inner diameter of the press-fit portion 8g, a surface that intersects the press-fit direction is formed by the difference in inner diameter between the sheet surface 8f and the press-fit portion 8g. In this embodiment, this surface is defined as a stepped portion 8h. By pressing down the stepped portion 8h, the discharge valve seat 8a can be press-fitted into the pump body 1 and can be easily press-fitted to the pump body 1.

  In the present embodiment, the cross-sectional area that intersects the press-fitting direction in the press-fitting portion 8g is smaller than the cross-sectional area that intersects the press-fitting direction in the seat portion 8i. Also in this case, the deformation of the seat surface 8f that occurs when the discharge valve seat 8a and the pump body 1 are press-fitted is reduced because the stiffness of the press-fit portion 8g is lower than the stiffness of the seat portion 8i. For this reason, the discharge valve mechanism 8 of the present embodiment has a good sealing property.

  FIG. 7 is a horizontal sectional view of the discharge valve mechanism 8 according to the second embodiment of the present invention. The same reference numerals as those in the first embodiment indicate the same meaning, and the description thereof is omitted. In the present embodiment, the discharge valve mechanism 8 performs press-fit coupling with the pump body 1 at two locations, the outer diameter of the press-fit portion 8g and the outer diameter of the seat portion 8j. When press-fitting with the pump body 1, the allowance for the outer diameter of the press-fit portion 8g and the outer diameter of the seat portion 8i can be reduced. That is, when the discharge valve seat 8a and the pump body 1 are press-fitted and joined, the deformation of the seat surface 8f is reduced and the sealing performance is improved. In addition, since fuel leakage is prevented at two locations, the outer diameter of the press-fit portion 8g and the outer diameter of the seat portion 8i, the risk of fuel leakage from the press-fit connection can be further reduced.

  Further, during the downward stroke of the plunger 2, when pressurized fuel flows from the discharge valve chamber 12a into the discharge valve mechanism 8 and a high pressure acts on the valve body 8b, the valve body 8b moves to the pressurization chamber 11 side. . At this time, since a high pressure is applied to the seat surface 8f through the valve body 8b, the seat surface 8f spreads greatly in the diameter method, and the sealing performance may be lost. However, in the case of the present embodiment, since there are two press-fitting locations, even when a high pressure is applied to the valve body 8b, the movement of the seat surface 8f is suppressed. That is, the deformation of the seat surface 8f that occurs during the downward stroke of the plunger 2 can be reduced.

  FIG. 8 is a horizontal sectional view of the discharge valve mechanism 8 according to the third embodiment of the present invention. The same reference numerals as those in the first embodiment indicate the same meaning, and the description thereof is omitted. The discharge valve mechanism 8 of the present embodiment is characterized in that the inner diameter of the seat portion 8i is equal to the inner diameter of the press-fit portion 8g.

  Since the inner diameters of the press-fit portion 8g and the seat portion 8j are the same, the number of man-hours is reduced, and it is possible to easily manufacture compared to shapes having different inner diameters. Therefore, the manufacturing cost can be reduced.

  FIG. 9 is a horizontal sectional view of the discharge valve mechanism 8 according to the fourth embodiment of the present invention. The same reference numerals as those in the first embodiment indicate the same meaning, and the description thereof is omitted. The discharge valve mechanism 8 of the present embodiment is characterized in that the discharge valve seat 8a has a tapered inner diameter formed from the press-fit portion 8g to the seat surface 8f.

  When the fuel passes through the inner diameter of the discharge valve seat 8a, fluid separation may occur if the inner diameter changes rapidly and an edge is present. And when it becomes below the saturated vapor pressure of fuel, cavitation bubbles are generated. There is a possibility that cavitation erosion that the sheet surface 8f is damaged by the energy when the cavitation bubbles collapse is generated. When this damage progresses, there is a possibility that a gap is generated between the valve body 8b and the seat surface 8f, and the fuel cannot be completely sealed. For this reason, making the inner diameter of the discharge valve seat 8a into a tapered shape is effective as a countermeasure against cavitation erosion.

DESCRIPTION OF SYMBOLS 1 Pump body 2 Plunger 6 Cylinder 7 Seal holder 8 Discharge valve mechanism 8a Discharge valve seat 8b Valve body 8c Elastic member 8d Discharge valve stopper 8e Contact part 8f Seat surface 8g Press-in part 8h Step part 8i Seat part 9 Pressure pulsation reduction mechanism 10a Low-pressure fuel suction port 11 Pressurization chamber 12 Fuel discharge port 13 Plunger seal 30 Suction valve 40 Rod biasing spring 43 Electromagnetic coil 100 Pressure pulsation propagation prevention mechanism 101 Valve seat 102 Valve 103 Spring 104 Spring stopper 200 Relief valve 201 Relief body 202 Valve 203 Valve holder 204 Relief spring 205 Spring stopper 300 Electromagnetic suction valve mechanism

Claims (6)

A pressurization chamber, a valve body provided on the discharge side of the pressurization chamber, and a discharge valve seat on which the valve body is seated , wherein the discharge valve seat is a press-fit portion for press-fitting to the body And a high pressure fuel supply pump provided with a seat surface in contact with the valve body,
The outer diameter of the press fit portion, the rather small compared to the outside diameter in the region from the sheet surface is formed in the press-fit direction by the press-fit portion, and smaller <br/> than the outer diameter of the seat surface High pressure fuel supply pump characterized by The high-pressure fuel supply pump according to claim 1,
A high pressure fuel supply pump characterized in that an inner diameter of the seat surface is larger than an outer diameter of the press-fitting portion. The high-pressure fuel supply pump according to claim 1,
A high-pressure fuel supply pump characterized in that an inner diameter in a region formed in the press-fitting direction from the press-fitting portion to the seat surface is equal to the inner diameter of the press-fitting portion. The high-pressure fuel supply pump according to claim 1,
A high-pressure fuel supply pump that performs press-fit coupling at two locations of an outer diameter in a region formed in the press-fit direction from the press-fit portion to the press-fit portion from the seat surface The high-pressure fuel supply pump according to claim 1,
The discharge valve seat has a tapered inner diameter formed from the seat surface to the press-fitting portion. The high-pressure fuel supply pump according to claim 1,
The discharge valve seat has a stepped portion that is a surface that intersects the press-fitting direction between the press-fit portion and the seat surface and inside the inner diameter of the seat surface,
The outer diameter of the press-fit portion is smaller than the outer diameter of the surface of the stepped portion.
High-pressure fuel supply pump

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