JP6483196B2 - High pressure fuel supply pump - Google Patents

Description

  The present invention relates to a high-pressure fuel supply pump that supplies high-pressure fuel to a fuel injection valve that injects fuel directly into a cylinder of an internal combustion engine, and more particularly to a high-pressure fuel pipe that includes an abnormally high discharge fuel pressure or a fuel accumulator chamber. A high-pressure fuel supply pump in which a safety valve (also called a relief valve) that opens when the pressure of the valve becomes abnormally high and returns fuel to the pressurizing chamber upstream of the discharge valve is incorporated in the main body of the high-pressure fuel supply pump About.

  In Japanese Patent Application Laid-Open No. 2004-138062, a fuel seat is provided in the center, a valve seat member having a seat surface formed around it, a valve body as a relief valve in contact with the seat surface, and the valve body as a seat A high-pressure fuel pump is described in which a relief valve mechanism composed of a spring member pressed against a surface is attached to a pump body so that the spring member is positioned on the pressurizing chamber side.

  In Japanese Patent No. 4415929, a valve seat is provided at the entrance of the pressurizing chamber side of the passage connecting the pressurizing chamber and the high-pressure passage, a relief valve is installed on the pressurizing chamber side of the valve seat, and the relief valve is A spring mechanism that biases the sheet toward the seat is provided on the high-pressure passage side.

JP 2004-138062 A Japanese Patent No. 4415929

  However, in the above prior art, the valve seat member of the discharge valve and the valve seat member of the relief valve are provided one each in two independent connection passages that connect the pressurizing chamber and the discharge passage. There has been a problem that a lot of man-hours are required for the machining work and the assembly work (particularly automatic assembly) of the two valves.

  An object of the present invention is to make it possible to install the valve seats of the relief valve and the discharge valve in one passage connecting the pressurizing chamber and the discharge passage.

An object of the present invention is to provide a discharge valve mechanism disposed on the discharge side of a pressurizing chamber in a high-pressure fuel supply pump, a high-pressure passage on the downstream side of the discharge valve mechanism, and a pressure in the high-pressure passage exceeding a set pressure. A relief valve mechanism that opens the valve to return the fuel, and a common valve seat member for the discharge valve mechanism and the relief valve mechanism, and is formed on the inner diameter side of the valve seat member, in the relief valve mechanism The valve seat member is formed with a first relief passage communicating with the downstream side and a second relief passage communicating with the high pressure passage by branching radially outward from the first relief passage. through a relief valve mechanism in communication with a downstream side of the high pressure passage and said relief valve mechanism,
Furthermore, one end is formed on the inner diameter side of the valve seat member and communicates with the pressurizing chamber, and the other end is formed on the inner diameter side of the valve seat member and communicates with the high-pressure passage, whereby the discharge valve mechanism is A plurality of discharge passages communicating with the pressurizing chamber and the high-pressure passage through the valve seat member. The plurality of discharge passages include the first relief passage and the plurality of second relief passages. Inclined with respect to the axial direction of the valve seat member to avoid,
Alternatively, a relief valve spring that biases the relief valve of the relief valve mechanism toward the relief valve seat portion of the valve seat member, and a relief valve that is disposed on the outer peripheral side of the relief valve spring, and the relief spring is disposed A relief valve body that constitutes a spring space, and the relief valve body and the valve seat member are fixed by press-fitting so that the relief valve mechanism and the valve seat member are configured as an integral unit, A discharge valve spring that urges the discharge valve of the discharge valve mechanism toward the discharge valve seat portion of the valve seat member; and a discharge valve spring that is disposed on an outer peripheral side of the discharge valve spring and in which the discharge valve spring is disposed A discharge valve body that constitutes a space, and the discharge valve body and the valve seat member are fixed by press-fitting, whereby the discharge valve mechanism and the relief valve A configuration and the valve seat member can be achieved in Rukoto constructed as an integral unit.

  According to the present invention configured as described above, the valve seats of the relief valve and the discharge valve can be configured by a single valve seat member, and the workability and assembly performance of the discharge valve and the relief valve are comprehensively improved.

1 is an overall longitudinal sectional view of a high-pressure fuel supply pump according to a first embodiment in which the present invention is implemented. It is the elements on larger scale for demonstrating the relief valve periphery of 1st Example by which this invention was implemented. It is a figure for demonstrating the assembly unit of the relief valve and discharge valve mechanism used for the Example of this invention. 1 is an example of a fuel supply system using a high-pressure fuel supply pump according to a first embodiment in which the present invention is implemented. It is a pressure waveform in each part in the high-pressure fuel supply pump of the first embodiment in which the present invention is implemented, and in the common rail. It is a figure for demonstrating the assembly unit of the relief valve and discharge valve mechanism of 2nd Example by which this invention was implemented.

  The present invention will be described in detail below based on embodiments shown in the drawings.

  The first embodiment of the present invention will be described below with reference to FIGS.

  The configuration and operation of the system will be described with reference to the overall configuration diagram of the system shown in FIG.

  A portion surrounded by a broken line A indicates a high-pressure pump main body, and the mechanisms and components shown in the broken line indicate that the high-pressure pump main body 1 is integrally incorporated.

  The fuel in the fuel tank 20 is pumped up by the feed pump 21 and sent to the suction joint 10 a of the high-pressure pump main body 1 through the suction pipe 28.

  The fuel that has passed through the suction joint 10a reaches the suction port 30a of the electromagnetic suction valve 30 constituting the variable capacity mechanism via the pressure pulsation reducing mechanism 9 and the suction passage 10d. The pulsation preventing mechanism 9 will be described in detail later.

  The electromagnetic suction valve 30 includes an electromagnetic coil 30b, and when the electromagnetic coil 30b is energized, the compressed state of the spring 33 is maintained while the electromagnetic plunger 30c is moved rightward in FIG. A suction valve body 31 attached to the tip of the electromagnetic plunger 30c opens a suction port 32 connected to the pressurizing chamber 11 of the high-pressure pump.

  When the electromagnetic coil 30b is not energized and there is no fluid differential pressure between the suction passage 10d (suction port 30a) and the pressurizing chamber 11, the biasing force of the spring 33 causes the suction valve body 31 to The suction port 32 is energized in the valve closing direction and is closed.

  Specifically, it operates as follows.

  When the plunger 2 is displaced downward in FIG. 1 due to the rotation of the cam, which will be described later, and is in the suction process state, the volume of the pressurizing chamber 11 increases and the fuel pressure in the pressurizing chamber 11 decreases. When the fuel pressure in the pressurizing chamber 11 becomes lower than the pressure in the suction passage 10d (suction port 30a) in this step, the valve opening force (suction valve body 31 shown in FIG. 4), a force to be displaced to the right in FIG. 4 is generated.

  By the valve opening force due to this fluid differential pressure, the suction valve body 31 is set to open over the biasing force of the spring 33 and open the suction port 32.

  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 30, an electric current flows through the electromagnetic coil 30b of the electromagnetic intake valve 30, and the electromagnetic plunger 30c is generated by the magnetic biasing force. 1 moves to the left of FIG. 1 (right of FIG. 4), and the state where the spring 33 is compressed is maintained. As a result, the state in which the suction valve body 31 opens the suction port 32 is maintained.

  When the plunger 2 finishes the suction process and shifts to the compression process while maintaining the application state of the input voltage to the electromagnetic suction valve 30, when the plunger 2 moves to the compression process (a state of moving upward in FIG. 1). Since the energized state of the electromagnetic coil 30b is maintained, the magnetic biasing force is maintained, and the suction valve body 31 is still open.

  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 suction valve body 31 that is opened again, and the suction passage 10 d (suction). Since the pressure is returned to the port 30a), the pressure in the pressurizing chamber does not increase. This process is called a return process.

  In this state, when the control signal from the ECU 27 is canceled and the energization to the electromagnetic coil 30b is cut off, the magnetic biasing force acting on the electromagnetic plunger 30c is after a certain time (after magnetic and mechanical delay time). Erased. Since the biasing force by the spring 33 is acting on the suction valve body 31, the suction valve body 31 closes the suction port 32 by the biasing force by the spring 33 when the electromagnetic force acting on the electromagnetic plunger 30 c disappears. When the suction port 32 is closed, the fuel pressure in the pressurizing chamber 11 increases with the upward movement of the plunger 2 from this time. When the pressure in the high pressure passage 12 becomes equal to or higher than that, the high pressure discharge of the fuel remaining in the pressurizing chamber 11 is performed via the discharge valve mechanism 8 and supplied to the common rail 23. This process is called a discharge process. That is, the compression process of the plunger 2 (the ascending process from the lower start point to the upper start point) includes a return process and a discharge process.

  And the quantity of the high pressure fuel discharged can be controlled by controlling the timing which cancels | releases the electricity supply to the electromagnetic coil 30c of the electromagnetic suction valve 30. FIG. If the timing of releasing the energization of the electromagnetic coil 30c is advanced, the ratio of the return process in the compression process is small and the ratio of the discharge process is large. That is, the amount of fuel returned to the suction passage 10d (suction port 30a) is small, and the amount of fuel discharged at high pressure is large. On the other hand, if the timing of releasing the energization is delayed, the ratio of the return process in the compression process is large and the ratio of the discharge process is small. That is, the amount of fuel returned to the suction passage 10d (suction port 30a) is large, and the amount of fuel discharged at high pressure is small. The timing for releasing the energization of the electromagnetic coil 30c is controlled by a command from the ECU.

  By configuring as described above, the amount of fuel discharged at a high pressure can be controlled to the amount required by the internal combustion engine by controlling the timing of releasing the energization of the electromagnetic coil 30c.

  A discharge valve mechanism 8 is provided at the outlet of the pressurizing chamber 11. The discharge valve mechanism 8 includes a discharge valve seat portion 8a, a discharge valve 8b, and a discharge valve spring 8c. When there is no fuel differential pressure in the pressurizing chamber 11 and the high pressure passage 12, the discharge valve 8b is biased by the discharge valve spring 8c. Thus, it is pressed against the discharge valve seat portion 8a and is in a closed state. Only when the fuel pressure in the pressurizing chamber 11 becomes higher than the fuel pressure in the high-pressure passage 12, the discharge valve 8 b opens against the discharge valve spring 8 c, and the fuel in the pressurizing chamber 11 passes through the high-pressure passage 12. After that, high pressure is discharged to the common rail 23. At this time, the fuel passes through the inside of the relief valve mechanism 200 and flows to the discharge valve 8a, but the relief valve itself remains closed, and the valve opening operation is not performed.

  Thus, the fuel guided to the fuel inlet 10 a is pressurized to a high pressure by the reciprocating motion of the plunger 2 in the pressurizing chamber 11 of the pump body 1, and is pumped from the high pressure passage 12 to the common rail 23.

  An injector 24 and a pressure sensor 26 are attached to the common rail 23. The injectors 24 are mounted in accordance with the number of cylinders of the internal combustion engine, open and close according to the control signal of the ECU 27, and inject fuel directly into the cylinders.

  The discharge valve seat portion 8a is further provided with a relief passage 200g that communicates the downstream side of the discharge valve 8b and the pressurizing chamber 11, bypassing the discharge valve, separately from the discharge flow path.

  The relief passage 200g is provided with a relief valve 200b that restricts the flow of fuel in only one direction from the discharge passage to the pressurizing chamber 11. The relief valve 200b is pressed against the relief valve seat portion 200a by a relief spring 200c that generates a pressing force. When the pressure difference between the pressurizing chamber and the relief passage exceeds a specified pressure, the relief valve 200b is relieved. The valve seat part 200a is set so as to be opened away from the valve seat part 200a.

  When an abnormally high pressure occurs in the common rail 23 or the like due to a failure of the injector 24 or the like, when the differential pressure between the relief passage 200g and the pressurizing chamber 11 exceeds the valve opening pressure of the relief valve 200b, the relief valve 200b opens and the abnormally high pressure is generated. The fuel thus obtained is returned from the relief passage 200g to the pressurizing chamber 11, and the high-pressure section piping such as the common rail 23 is protected.

  Hereinafter, the configuration and operation of the high-pressure fuel pump will be described in more detail with reference to FIGS.

  A pressurizing chamber 11 is formed at the center of the pump body, and an electromagnetic suction valve 30 for supplying fuel to the pressurizing chamber 11 and a discharge valve for discharging fuel from the pressurizing chamber 11 to the high-pressure passage 12. A mechanism 8 is provided. A cylinder 6 that guides the forward / backward movement of the plunger 2 is attached so as to face the pressurizing chamber 11.

  The cylinder 6 has an outer periphery held by a cylinder holder 7 and is fixed to the pump main body 1 by screwing a male screw engraved on the outer periphery of the cylinder holder 7 into a female screw engraved in the pump main body 1. The cylinder 6 holds the plunger 2 that moves forward and backward in the pressurizing chamber so as to be slidable along the forward and backward movement direction.

  The lower end of the plunger 2 is provided with a tappet 3 that converts the rotational motion of the cam 5 attached to the camshaft of the engine into a vertical motion and transmits it to the plunger 2. The plunger 2 is pressure-bonded to the tappet 3 by a spring 4 through a retainer 15. Thereby, the plunger 2 can be moved back and forth (reciprocated) up and down with the rotational movement of the cam 5.

  Further, the plunger seal 13 held at the lower end of the inner periphery of the cylinder holder 7 is installed in a state of slidably contacting the outer periphery of the plunger 2 at the lower end of the cylinder 6 in the figure. The blow-by gap between 6 and 6 is sealed to prevent fuel from leaking outside. At the same time, lubricating oil (including engine oil) that lubricates the sliding portion in the engine room is prevented from flowing into the pump body 1 through the blow-by gap.

  The damper cover 14 is provided with a pressure pulsation reduction mechanism 9 that reduces the pressure pulsation generated in the pump from spreading to the fuel pipe 28.

  When the fuel once sucked into the pressurizing chamber 11 is returned to the suction passage 10d (suction port 30a) again through the opened valve body 31 due to the capacity control state, to the suction passage 10d (suction port 30a). Pressure pulsation is generated in the suction passage 10 by the returned fuel. However, the suction passage 10c (formed between the cup-shaped damper cover 14 and the annular recess formed on the outer periphery of the pump body) as a damper chamber provided in the suction passage 10 has a corrugated plate shape. Two disk-shaped metal diaphragms are joined at the outer periphery, and a metal damper 9 into which an inert gas such as argon is injected is attached. Pressure pulsation is absorbed and reduced by the metal damper 9 expanding and contracting. Is done.

  The discharge valve mechanism 8 and the relief valve mechanism 200 are integrated by the discharge valve seat portion 8a and the relief valve seat portion 200a being constituted by one sheet member, and are formed into a cylindrical discharge opening portion formed in the pressurizing chamber 11. The inside of 11A is press-fitted from the outside toward the pressurizing chamber 11, and is held inside the cylindrical discharge opening 11A.

  The fuel pressurized in the pressurizing chamber 11 passes through a hole 200h provided in the center of the relief valve stopper 200f, passes through a gap between the string-like relief valve springs 200c, and passes through the seat member (relief valve seat portion 200a, discharge valve seat portion). It flows to the discharge valve 8b through the discharge passage 8e provided in 8a).

  The discharge valve 8b of the discharge valve unit configured as described above has the discharge valve 8b applied to the discharge valve seat portion 8a by the biasing force of the discharge valve spring 8c when there is no fuel differential pressure in the pressurizing chamber 11 and the high pressure passage 12. Crimped and closed. Only when the fuel pressure in the pressurizing chamber 11 becomes higher than the fuel pressure in the high pressure passage 12, the discharge valve 8 b opens against the discharge valve spring 8 c, and the fuel in the pressurizing chamber 11 is discharged from the discharge valve holder. High pressure is discharged to the common rail 23 through the high pressure passage 12 through the passage hole provided in 8d. At this time, the fuel passes through the inside of the relief valve mechanism 200 and flows to the discharge valve, but the relief valve itself remains closed, and the relief valve 200b does not open.

  With the above configuration, the discharge valve mechanism 8 functions as a check valve that restricts the direction of fuel flow.

  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 relief valve seat portion 200a, a relief valve 200b, a relief valve spring 200c, a relief valve body 200d, a ball valve holder 200e, and a relief spring stopper 200f.

  The relief valve seat part 200a is pressed by the relief valve body 200d by press-fitting and fixing (welding) the relief valve seat part 200a side of the valve seat member S to one end opening of the cylindrical relief valve body 200d. Siege around. Then, the relief valve 200b, the ball valve holder 200e, and the relief valve spring 200c are inserted into the relief valve body 200d from the other end side of the cylindrical relief valve body 200d, and the relief valve spring stopper 200f is inserted into the cylindrical relief valve body. The interior member is held inside the cylindrical relief valve body 200d by being press-fitted into and fixed to the inner periphery of 200d. The pressing force by the relief spring 200c can be set by the press-fitting position of the relief valve spring stopper 200f. The valve opening pressure of the relief valve 200b is determined to a specified value by the pressing force by the relief valve spring 200c. The relief valve spring stopper 200f is first press-fitted and fixed, and the relief valve spring 200c, the ball valve holder 200e, and the relief valve 200b are set in the cylindrical relief valve body 200d, and the valve seat member S is formed in the cylindrical shape. It can also be fixed to one end opening of the relief valve body 200d. At this time, it can be adjusted by the press-fitting position of the cylindrical relief valve body 200d and the valve seat member S.

  On the opposite side of the valve seat member S from the relief valve seat portion 200a, a discharge valve seat portion 8a is formed, and the discharge valve seat portion 8a and the relief valve seat portion 200a are constituted by one valve seat member S. The discharge valve seat 8S is composed of an annular projection formed on the outer edge of the end of the valve seat member S. By fitting the open end side inner peripheral surface of the cup-type discharge valve holder 8d to the outer periphery of the valve seat member S and fixing it by welding or the like, the discharge valve holder 8d surrounds the periphery of the discharge valve seat portion 8a. A discharge valve spring 8c and a flat discharge valve 8b are mounted inside the discharge valve holder 8d, and the flat discharge valve 8b is pressed against the annular discharge valve seat 8S by the discharge valve spring 8c. ing.

  On the inner diameter side of the discharge valve seat 8S, the other end of the discharge passage 8e having one end opened to the pressurizing chamber 11 side is opened. The discharge passage 8e is formed as a plurality of passages inclined around the relief passage 200gS, avoiding the relief passage 200gS formed in the center. Specifically, one end of the discharge passage 8e opens at a portion located radially outward from the central portion where the relief passage 200gS at the end of the valve seat member S on the pressure chamber 11 side opens. The other end of the discharge passage 8e is opened at the end of the valve seat member S on the side opposite to the pressurizing chamber 11 and located on the inner diameter side of the discharge valve seat portion 8a that protrudes from the outer edge of the valve seat member S. Yes. As a result, the discharge passage 8e is formed as a straight pipe passage that is inclined with respect to the central axis in the longitudinal direction of the sheet member S by the difference between the radial positions of the opening positions at both ends. Thus, the required passage cross-sectional area of the discharge passage 8e can be secured without increasing the diameter of the valve seat member S on the discharge valve seat portion 8a side.

  On the other hand, the relief passage 200g formed in the central portion of the valve seat member S includes a single straight pipe portion 200gS that opens to the relief valve seat portion 200S formed at one end of the valve seat member S on the pressurizing chamber 11 side. Have. The straight pipe portion 200gS branches into a plurality of radial passages 200gR after passing through the discharge valve side end of the relief valve body 200d, and is connected to the high-pressure passage 12 through the opening on the outer periphery of the valve seat member S.

  Thus, the relief valve mechanism 200 and the discharge valve mechanism 8 are configured as one unit VU.

  The unit VU of the discharge valve mechanism 8 and the relief valve mechanism 200 that are unitized in this way is configured by pressing the outer periphery of the relief valve body 200d portion of the unit VU into the inner peripheral wall of the cylindrical opening 11A provided in the pump body 1. Fixed. Next, the discharge joint 12a is disposed so as to cover the discharge valve mechanism 8 of the unit VU, and is fixed to the pump body 1 by welding or screwing.

  The joint 12a serves as a pipe joint for flowing high-pressure fuel to the common rail 23, and the high-pressure passage 12 is formed therein.

  Thus, by integrating the relief valve mechanism 200 with the discharge valve mechanism 8, an increase in the volume of the pressurizing chamber 11 can be minimized. Further, since the diameter of the relief valve mechanism 200 is smaller than the dimension in the axial direction, it intersects the plunger 2 as in this embodiment, compared to the case where the relief valve is arranged in the same reciprocating direction of the plunger 2 of the high pressure fuel supply pump. The direction of the reciprocating same direction of the plunger 2 of the high-pressure fuel supply pump can be reduced by arranging in the direction.

  Furthermore, since the fuel flowing from the pressurizing chamber 11 to the discharge valve mechanism 8 always passes through the relief valve mechanism 200, air or vaporized fuel bubbles are likely to be discharged from the discharge valve 8a, particularly when the engine is started. Prevents deterioration of compression function due to air bubbles. In addition, the occurrence of cavitation is suppressed. That is, when the relief passage is formed at a position away from the discharge fuel passage as in the prior art, if bubbles of vaporized fuel stay in the relief passage, the bubbles are not excluded until the relief valve is opened, and the compression function is It was reduced and also caused cavitation. In this embodiment, the engine passes through the relief valve mechanism 200, that is, around the relief valve spring 200c and the ball valve holder 200e at the same time as the engine is started, so that bubbles of vaporized fuel staying in the relief valve mechanism 200 are quickly removed. Can be eliminated.

  Further, it is not necessary to separately incorporate the relief valve mechanism 200 and the discharge valve mechanism 8 into the pump main body 1, the amount of passage processing of the pump main body 1 can be reduced, and productivity in both processing and assembling can be improved. In addition, since the relief valve mechanism 200 and the discharge valve mechanism 8 can be incorporated in the automated line at the same time, the number of work steps in the automated line is reduced.

  FIG. 4 shows an example of the pressure waveform at each part when the fuel is normally pressurized to a high pressure and fed to the common rail 23 by the high-pressure fuel supply pump. The target fuel pressure of the common rail 23 is adjusted to 15 MPa (megapascal), and the valve opening pressure of the relief valve 200b is adjusted to 18 MPa (megapascal).

  While the plunger 2 is moving up, a pressure overshoot occurs in the pressurizing chamber 11 from the moment when the plunger 2 moves up to the pressurizing step. The pressure overshoot generated in the pressurizing chamber 11 propagates from the high pressure passage 12 to the relief passage 200g (S, R) and the relief valve 200b. As a result, a pressure higher than the valve opening pressure of the relief valve 200b is applied to the inlet of the relief valve 200b. On the other hand, since the outlet of the relief valve 200b is the pressurizing chamber 11, a pressure overshoot generated in the pressurizing chamber 11 acts on the outlet. The pressure overshoot in the pressurizing chamber 11 is larger than the pressure overshoot in the relief passage 200g. Therefore, since the resultant force of these pressure overshoots acts in the direction of closing the relief valve 200b, the relief valve 102 does not open.

  As described above, even if the relief valve mechanism 200 for preventing damage due to abnormally high pressure in the high-pressure passage including the common rail 23 from the downstream of the discharge valve mechanism 8 is installed in the discharge joint 12a of the high-pressure fuel supply pump, It is possible to obtain a high-pressure fuel supply pump that does not decrease and does not decrease volumetric efficiency.

  Next, a case where an abnormally high pressure occurs in the high-pressure passage including the common rail 23 from the downstream of the discharge valve mechanism 8 due to a failure of the injector 24 or the like will be described in detail.

  When the volume of the pressurizing chamber starts to decrease due to the movement of the plunger, the pressure in the pressurizing chamber increases as the volume decreases. When the pressure in the pressurizing chamber finally becomes higher than the pressure in the discharge passage, the discharge valve opens and fuel is discharged from the pressurization chamber to the discharge passage. From the moment when the discharge valve is opened to immediately after, the pressure in the pressurizing chamber overshoots and becomes a very high pressure.

  This high pressure is also propagated in the discharge channel, and the pressure in the discharge channel also overshoots at the same timing.

  If the outlet of the relief valve is connected to the suction flow path here, the pressure difference between the inlet and outlet of the relief valve becomes larger than the opening pressure of the relief valve due to pressure overshoot in the discharge flow path. As a result, the relief valve malfunctions.

  On the other hand, in the embodiment, since the outlet of the relief valve is connected to the pressurizing chamber, the pressure in the pressurizing chamber acts on the outlet of the relief valve, and the pressure in the discharge channel is applied to the inlet of the relief valve. Works.

  Here, since pressure overshoot occurs at the same timing in the pressurizing chamber and in the discharge flow path, the pressure difference between the inlet and outlet of the relief valve does not exceed the valve opening pressure of the relief valve. That is, the relief valve does not malfunction.

  When the volume of the pressurizing chamber starts to increase due to the movement of the plunger, the pressure in the pressurizing chamber decreases as the volume increases, and when the pressure becomes lower than the pressure in the suction passage, fuel flows into the pressurization chamber from the suction passage. To do. When the volume of the pressurizing chamber starts to decrease again due to the movement of the plunger, the fuel is pressurized to a high pressure and discharged by the above mechanism.

  Here, if the fuel injection valve malfunctions, that is, if the injection function is stopped and the fuel sent to the common rail cannot be supplied to the cylinder, the fuel accumulates between the discharge valve and the common rail, and the fuel pressure becomes abnormally high.

  In this case, if the pressure rises slowly, an abnormality is detected by the pressure sensor provided on the common rail, and a safety function is activated to control the capacity control mechanism provided in the suction passage to reduce the discharge amount. High pressure cannot be dealt with by feedback control using this pressure sensor.

  Also, if the capacity control mechanism provided in the suction port or overflow passage breaks down and does not function as it is at the maximum capacity, the discharge pressure becomes abnormally high in the operating state where not much fuel is required. Become.

  In this case, even if the common rail pressure sensor detects an abnormally high pressure, the capacity control mechanism itself is broken, and thus the abnormally high pressure cannot be eliminated.

  In addition, when the injection of the injector is stopped after the engine is stopped or during operation, the fuel in the common rail may normally increase in pressure due to thermal expansion due to the heat on the engine side.

  When such an abnormal high pressure occurs, the relief valve of the embodiment functions as a safety valve.

  When the volume of the pressurizing chamber starts to increase due to the movement of the plunger, the pressure in the pressurizing chamber decreases as the volume increases, and the pressure at the relief valve inlet, that is, the discharge flow path, becomes the pressure at the relief valve outlet, that is, the pressure in the pressurizing chamber. If the pressure becomes higher than the opening pressure of the relief valve, the valve is opened, and the fuel having an abnormally high pressure in the discharge passage is returned to the pressurizing chamber. As a result, even when an abnormal high pressure occurs, the pressure does not exceed the specified high pressure, and the high pressure piping system and the like are protected.

  In the case of the first embodiment in which the relief valve mechanism 200 is installed between the discharge valve mechanism 8 and the pressurizing chamber 11, the valve opening pressure is set between the inlet and the outlet of the relief valve 102 by the mechanism described above during the discharge process. Since the above pressure difference does not occur, the relief valve does not open accidentally at the peak pressure during the discharge process.

  In the suction process and the return process, the fuel pressure in the pressurizing chamber 11 decreases to the same low pressure as that of the suction pipe 28. On the other hand, the pressure in the relief passage 200g rises to the same pressure as that of the common rail 23. When the pressure difference between the relief passage 200g and the pressurizing chamber becomes equal to or higher than the opening pressure of the relief valve 200b, the relief valve 200b is opened, and the abnormally high pressure fuel is returned from the relief chamber 200b to the pressurizing chamber 11. High-pressure piping such as the common rail 23 is protected.

  The high-pressure fuel supply pump needs to pressurize the fuel to a very high pressure of several MPa to several tens of MPa, and the opening pressure of the relief valve must be higher. If the valve opening pressure is set below that, the relief valve opens even if the fuel is normally pressurized by the high-pressure fuel supply pump. This malfunction of the relief valve leads to a decrease in discharge amount and energy efficiency as a high-pressure fuel supply pump.

  Therefore, in order to set the valve opening pressure of the relief valve to such a very high pressure, it is necessary to increase the urging force by the relief spring, and the size of the relief spring must be increased.

  However, when a relief spring is provided in the pressure chamber or the relief passage on the pressure chamber side, the increase in the size of the relief spring increases the volume in the pressure chamber or the volume in the chamber that leads to the pressure chamber. Will be.

  The high pressure fuel supply pump reduces the volume in the pressurized chamber by the movement of the plunger and compresses the fuel to pressurize and discharge the fuel to a high pressure. The fuel had to be pressurized to a high pressure, and as a high-pressure fuel supply pump, there was a problem that the compression rate was lowered and the energy efficiency was lowered.

  Furthermore, it becomes impossible to pressurize only the fuel required by the internal combustion engine to a high pressure. In this embodiment, the discharge valve and the relief valve are integrated to minimize the increase in the pressure chamber volume.

  Furthermore, since the fuel flowing from the pressurizing chamber 11 to the discharge valve always passes through the relief valve mechanism, air or vaporized fuel bubbles are likely to be discharged from the discharge valve, particularly when the engine is started. Can be prevented.

  A second embodiment will be described with reference to FIG.

  In the example shown in FIG. 6, there is no relief valve spring stopper 200f as shown in FIG. 3 of the first embodiment, and the relief valve spring 200c is received by the bottom surface formed integrally with the relief valve body 200d.

  The relief valve seat portion 200a (an integral part of the discharge valve seat portion 8a) is fixed to the relief valve body 200d by press-fitting or the like. The relief valve spring 200c is set depending on the depth of the relief valve seat portion 200a at this time. The load can be adjusted, and the relief valve opening pressure can be adjusted or changed.

  The above is an example of further reducing the number of parts and increasing the productivity, but the performance as a relief valve is the same as that of the first embodiment.

  A second relief passage that connects the downstream of the discharge valve mechanism 8 and the low-pressure fuel passage on the upstream side of the intake valve 32 is provided, and the second relief passage has a pressure higher than the operation set pressure of the relief valve mechanism 200 described above. A safer system can be obtained by installing the second relief valve mechanism of the set pressure.

  Further, the orifice 200Y shown in FIG. 4 dampens the peak pressure of the high pressure passage, and may be incorporated in the pump body, provided in the high pressure passage, or provided at the inlet of the relief passage.

The present embodiment described above has an effect that can solve the following problems of the prior art.
(1) Since the relief valve mechanism is installed in the pressurizing chamber or the passage leading to the pressurizing chamber, the volume of the pressurizing chamber increases and the compression efficiency decreases.
(2) Furthermore, the spring mechanism of the relief valve connected to the pressurizing chamber has a bag path shape, which makes it difficult for air or vaporized fuel bubbles to escape, and the compression function further decreases.

  In this embodiment, even if a relief valve mechanism for returning abnormally high-pressure fuel in the high-pressure passage to the pressurizing chamber is installed in the pump body, air bubbles in the compression chamber are improved and compression efficiency is high, that is, energy efficiency is high. A high-capacity high-pressure fuel pump can be provided.

  According to this embodiment, when an abnormally high pressure occurs due to a failure of the fuel injection valve, the fuel pressurized to an abnormally high pressure is released from the relief valve to the pressurizing chamber, and the piping and other equipment are abnormal. It is possible to provide a high-pressure fuel pump having a high compression ratio, that is, energy efficiency, while maintaining the effect of not being damaged by high pressure.

  The embodiments of the present embodiment are summarized as follows.

[Embodiment 1]
In a high-pressure fuel supply pump comprising a relief passage that returns abnormally high-pressure fuel from a high-pressure passage downstream of a discharge valve to a pressurizing chamber that pressurizes fuel, and a relief valve mechanism that opens and closes the relief passage.
A high-pressure fuel pump in which the fuel from the pressurizing chamber is set so that fuel flows to the discharge valve through the relief valve mechanism.

[Embodiment 2]
Embodiment 1
The high-pressure fuel supply pump, wherein the discharge valve seat and the relief valve seat are formed of a single component.

[Embodiment 3]
Embodiment 1
One or a plurality of passages to the discharge valve seat are formed in the discharge valve seat or the relief valve seat.

[Embodiment 4]
Embodiment 1
One or a plurality of passages to the relief valve discharge valve seat are formed in the discharge valve seat or the relief valve seat.

[Embodiment 5]
Embodiment 1
The high-pressure fuel supply pump, wherein the relief valve mechanism and the discharge valve mechanism form an independent unit as an assembly.

[Embodiment 6]
In what is described in embodiment 5,
An assembly unit of the relief valve mechanism and the discharge valve mechanism is mounted from the inside of the pressurizing chamber.

[Embodiment 7]
In what is described in embodiment 5,
An assembly unit of the relief valve mechanism and the discharge valve mechanism is mounted from the outside of the pump.

[Embodiment 8]
In what is described in embodiment 1,
A high-pressure fuel supply pump, wherein at least the relief valve or the discharge valve is mounted in a joint to a discharge pipe.

[Embodiment 9]
In what is described in embodiment 1,
The high-pressure fuel supply pump, wherein the spring load setting of the relief valve is adjusted by the mounting depth of the discharge valve seat or the relief valve seat.

[Embodiment 10]
Embodiment 1
The high-pressure fuel supply pump, wherein the relief passage is open to a side peripheral surface of the pressurizing chamber.

[Embodiment 11]
Embodiment 1
The high-pressure fuel supply pump, wherein the return passage is open to the top surface of the pressurizing chamber.

[Embodiment 12]
Embodiment 1
A plurality of relief passages provided with the relief valve mechanism are provided;
At least one of the relief passages has an outlet opening in the low pressure passage.

[Embodiment 13]
Embodiment 12
The operating pressure of the relief valve mechanism provided in the relief passage opening in the low pressure passage is set higher than the operating pressure of the relief valve mechanism provided in the relief passage opening in the pressurizing chamber. Fuel supply pump.

[Embodiment 14]
Embodiment 1
A high-pressure fuel supply pump in which the valve drive mechanism includes an electromagnetic drive mechanism.

  Although the present invention has been described by taking a high-pressure fuel supply pump for a gasoline engine as an example, it can also be used for a high-pressure fuel supply pump for a diesel internal combustion engine.

  Further, the invention can be applied to any type equipped with a capacity control mechanism regardless of the type or installation position of the capacity control mechanism.

DESCRIPTION OF SYMBOLS 1 Pump main body 2 Plunger 8 Discharge valve mechanism 11 Pressurization chamber 24 Injector 30 Electromagnetic suction valve 200 Relief valve mechanism 200b Relief valve 200g Relief passage

Claims (7)

A discharge valve mechanism disposed on the discharge side of the pressurizing chamber, a downstream high-pressure passage in the discharge valve mechanism, and a relief valve mechanism that opens and returns fuel when the pressure in the high-pressure passage exceeds a set pressure And a common valve seat member for the discharge valve mechanism and the relief valve mechanism,
A first relief passage that is formed on the inner diameter side of the valve seat member and communicates with a downstream side of the relief valve mechanism, and a second branch that branches into a plurality radially outward from the first relief passage and communicates with the high-pressure passage. by the relief passage is formed in the valve seat member, and communicates the downstream side of the high pressure passage and said relief valve mechanism via the relief valve mechanism,
One end is formed on the inner diameter side of the valve seat member and communicates with the pressurizing chamber, and the other end is formed on the inner diameter side of the valve seat member and communicates with the high pressure passage through the discharge valve mechanism. A plurality of discharge passages communicating with the pressurizing chamber and the high pressure passage are formed in the valve seat member so that the plurality of discharge passages avoid the first relief passage and the plurality of second relief passages. And a high-pressure fuel supply pump that is inclined with respect to the axial direction of the valve seat member . The high-pressure fuel supply pump according to claim 1,
The first relief passage is a high-pressure fuel supply pump that is formed at a central portion in the radial direction of the valve seat member and communicates with a downstream side of the relief valve mechanism. The high-pressure fuel supply pump according to claim 2,
The high-pressure fuel supply pump, wherein the second relief passage is branched into a plurality of radial outer sides so as to be orthogonal to the first relief passage and communicates with the high-pressure passage. The high-pressure fuel supply pump according to claim 1 ,
The plurality of discharge passages are formed around the first relief passage so as to be inclined with respect to the axial direction of the valve seat member so as to avoid the first relief passage and the plurality of second relief passages. Fuel supply pump. The high-pressure fuel supply pump according to claim 1 ,
Each of the plurality of discharge passages is formed so that the other end on the high pressure passage side is located on the inner diameter side of the valve seat member with respect to one end on the pressure chamber side. pump. A discharge valve mechanism disposed on the discharge side of the pressurizing chamber, a downstream high-pressure passage in the discharge valve mechanism, and a relief valve mechanism that opens and returns fuel when the pressure in the high-pressure passage exceeds a set pressure And a common valve seat member for the discharge valve mechanism and the relief valve mechanism,
A first relief passage that is formed on the inner diameter side of the valve seat member and communicates with a downstream side of the relief valve mechanism, and a second branch that branches into a plurality radially outward from the first relief passage and communicates with the high-pressure passage. By forming a relief passage in the valve seat member, the high-pressure passage communicates with the downstream side of the relief valve mechanism via the relief valve mechanism,
A relief valve spring that biases the relief valve of the relief valve mechanism toward the relief valve seat portion of the valve seat member;
A relief valve body disposed on the outer peripheral side of the relief valve spring and constituting a relief valve spring space in which the relief spring is disposed,
The relief valve body and the valve seat member are fixed by press-fitting so that the relief valve mechanism and the valve seat member are configured as an integral unit ,
A discharge valve spring for biasing the discharge valve of the discharge valve mechanism toward the discharge valve seat portion of the valve seat member;
A discharge valve body disposed on the outer peripheral side of the discharge valve spring and constituting a discharge valve spring space in which the discharge valve spring is disposed,
The discharge valve body and said valve seat member by being press-fitted, the discharge valve mechanism, the relief valve mechanism and the valve high-pressure fuel supply pump seat and member Ru is constructed as an integral unit. The high-pressure fuel supply pump according to claim 6 ,
A high-pressure fuel supply pump in which a discharge joint that forms the high-pressure passage is configured separately from the integral unit.

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