JP6681487B2 - 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 directly injects fuel into a cylinder of an internal combustion engine, and particularly to a high-pressure fuel pipe including a fuel accumulator when the discharge fuel pressure is abnormally high. High-pressure fuel supply pump in which a safety valve (also called a relief valve) that opens when the pressure in the high-pressure fuel 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. Regarding

  In JP-A-2004-138062, a fuel passage is provided in the center and a seat surface is formed around the fuel passage, a valve body as a relief valve that abuts on the seat surface, and the valve body is seated. 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 located on the pressurizing chamber side.

  In Japanese Patent No. 4415929, a valve seat is provided at the inlet of the passage that connects the pressurizing chamber and the high-pressure passage, and a relief valve is installed on the pressurizing chamber side of the valve seat. It is described that a spring mechanism for urging the seat is provided on the high pressure passage side.

JP 2004-138062 A Japanese Patent No. 4415929

  However, in the above-mentioned conventional technique, the valve seat member of the discharge valve and the valve seat member of the relief valve are provided one by one in the two independent connection passages that connect the pressurizing chamber and the discharge passage. There is a problem that a lot of man-hours are required for the processing work of (1) and the assembling work of the two valves (especially automatic assembly).

  An object of the present invention is to enable the valve seats of the relief valve and the discharge valve to be installed in one passage connecting the pressurizing chamber and the discharge passage.

An object of the present invention is to provide a discharge valve mechanism provided on the discharge side of a pressurizing chamber, a high pressure passage provided on the downstream side of the discharge valve mechanism, and a relief valve due to a pressure difference between the high pressure passage and the pressurizing chamber. A relief valve mechanism that opens and returns the fuel on the high-pressure passage side to the pressurizing chamber, a discharge valve seat portion against which a discharge valve of the discharge valve mechanism is pressed, and a relief valve seat portion against which the relief valve of the relief valve mechanism is pressed. And a common valve seat member having, and the relief valve mechanism, the discharge valve mechanism, and the valve seat member are configured as one unit, and the relief valve mechanism includes the relief valve and the relief valve. comprising a relief valve spring that presses the valve seat, the load of the relief valve spring, the relief valve body of the relief valve mechanism provided on the outer peripheral side of the relief valve spring Against achievable with the Turkey is adjusted by mounting depth of the valve seat member. Alternatively, a first relief passage that is adjusted by a mounting depth of a relief valve spring stopper of the relief valve mechanism that receives the relief valve spring , is formed on an inner diameter side of the valve seat member, and communicates with a downstream side of the relief valve mechanism. And a second relief passage branching radially outward from the first relief passage to communicate with the high pressure passage, the second relief passage being formed in the valve seat member, and thus the high pressure passage through the relief valve mechanism. This can be achieved by communicating with the downstream side of the relief valve mechanism.

  According to the present invention thus configured, the valve seats of the relief valve and the discharge valve can be composed of one valve seat member, and the workability and the assemblability of the discharge valve and the relief valve are comprehensively improved.

It is the whole longitudinal section of the high-pressure fuel supply pump of the 1st example in which the present invention was implemented. It is a partial enlarged view for explaining the relief valve circumference of the 1st example in which the present 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. It is an example of a fuel supply system using the high-pressure fuel supply pump of the first embodiment of the present invention. 3 is a pressure waveform in each part in the high-pressure fuel supply pump and the common rail according to the first embodiment of the present invention. It is a figure for demonstrating the assembly unit of the relief valve and discharge valve mechanism of 2nd Example in which this invention was implemented.

  BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on embodiments shown in the drawings.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

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

  A portion surrounded by a broken line A shows the high-pressure pump main body, and the mechanism and parts shown in the broken line show 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 10a of the high-pressure pump 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 that constitutes 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. When the electromagnetic coil 30b is energized, the electromagnetic plunger 30c is moved to the right in FIG. 1 and the compressed state of the spring 33 is maintained. 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 pressure difference between the suction passage 10d (suction port 30a) and the pressurization chamber 11, the suction valve element 31 is urged by the biasing force of the spring 33. The suction port 32 is closed by being biased in the valve closing direction.

  Specifically, it operates as follows.

  When the plunger 2 is displaced downward in FIG. 1 by the rotation of the cam 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. In this step, when the fuel pressure in the pressurizing chamber 11 becomes lower than the pressure in the suction passage 10d (suction port 30a), the suction valve body 31 has a valve opening force (the suction valve body 31 shown in FIG. 4) is generated on the left side of FIG.

  The suction valve body 31 is set to open the suction port 32 by overcoming the urging force of the spring 33 by the valve opening force due to the fluid pressure difference to open the valve.

  In this state, when a control signal from the engine control unit 27 (hereinafter referred to as ECU) is applied to the electromagnetic suction valve 30, a current flows through the electromagnetic coil 30b of the electromagnetic suction valve 30, and the electromagnetic urging force causes the electromagnetic plunger 30c. Moves to the left in FIG. 1 (to the right in FIG. 4), and the state in which the spring 33 is compressed is maintained. As a result, the state where 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 state where the input voltage is applied to the electromagnetic suction valve 30, when the plunger 2 shifts to the compression process (the state of moving upward in FIG. 1). Since the energization state of the electromagnetic coil 30b is maintained, the magnetic biasing force is maintained and the intake valve body 31 is still open.

  The volume of the pressurizing chamber 11 decreases with the compressive movement of the plunger 2. In this state, the fuel once sucked into the pressurizing chamber 11 again passes through the suction valve body 31 in the valve open state and the suction passage 10d (suction). Since it is returned to the port 30a), the pressure in the pressurizing chamber does not rise. This process is called a returning process.

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

  The amount of high-pressure fuel discharged can be controlled by controlling the timing at which the energization of the electromagnetic coil 30c of the electromagnetic suction valve 30 is released. If the timing of releasing the power supply to the electromagnetic coil 30c is advanced, the proportion of the returning step and the proportion of the discharging step in the compression step are small. That is, less fuel is returned to the suction passage 10d (suction port 30a), and more fuel is discharged under high pressure. On the other hand, if the timing of releasing the energization is delayed, the ratio of the returning process in the compression process is large and the ratio of the discharging process is small. That is, much fuel is returned to the suction passage 10d (suction port 30a), and less fuel is discharged under high pressure. The timing of releasing the power supply to the electromagnetic coil 30c is controlled by a command from the ECU.

  With the above configuration, the amount of fuel discharged at high pressure can be controlled to the amount required by the internal combustion engine by controlling the timing at which the power supply to the electromagnetic coil 30c is released.

  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, and when there is no fuel pressure difference between the pressurizing chamber 11 and the high pressure passage 12, the discharge valve 8b urges the discharge valve spring 8c. Thus, the valve is closed by being crimped onto the discharge valve seat portion 8a. 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 8b opens against the discharge valve spring 8c, and the fuel in the pressurizing chamber 11 is discharged. Then, the 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 introduced into the fuel intake port 10a 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 mounted on the common rail 23. The injectors 24 are mounted according to the number of cylinders of the internal combustion engine, and open / close valves according to the control signal of the ECU 27 to 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 with the discharge valve bypassed, separately from the discharge flow passage.

  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 becomes equal to or higher than a specified pressure, the relief valve 200b is relieved. The valve seat 200a is set apart from the valve seat 200a so that the valve is opened.

  When an abnormally high pressure is generated in the common rail 23 or the like due to a failure of the injector 24 or the like, and the differential pressure between the relief passage 200g and the pressurizing chamber 11 becomes equal to or higher than the valve opening pressure of the relief valve 200b, the relief valve 200b opens and the abnormally high pressure is generated. The fuel thus discharged is returned from the relief passage 200g to the pressurizing chamber 11, and the high-pressure pipes such as the common rail 23 are protected.

  The structure and operation of the high-pressure fuel pump will be described below in more detail with reference to FIGS.

  A pressurizing chamber 11 is formed in 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 for guiding the forward / backward movement of the plunger 2 is attached so as to face the pressurizing chamber 11.

  The outer circumference of the cylinder 6 is held by the cylinder holder 7, and the male thread engraved on the outer circumference of the cylinder holder 7 is fixed to the pump body 1 by screwing it into the female thread engraved on the pump 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 direction of forward and backward movement.

  At the lower end of the plunger 2, a tappet 3 is provided which converts the rotational movement of a cam 5 attached to the camshaft of the engine into vertical movement and transmits the vertical movement to the plunger 2. The plunger 2 is pressed against the tappet 3 by a spring 4 via a retainer 15. As a result, the plunger 2 can be moved up and down (reciprocating) along with the rotational movement of the cam 5.

  Further, the plunger seal 13 held at the lower end of the inner circumference of the cylinder holder 7 is installed so as to slidably contact the outer circumference of the plunger 2 at the lower end of the cylinder 6 in the figure, whereby the plunger 2 and the cylinder The blow-by gap with 6 is sealed to prevent fuel from leaking to the outside. At the same time, the 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 reducing mechanism 9 that reduces the pressure pulsation generated in the pump from propagating 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) through the suction valve body 31 which is in the valve open state again due to the capacity control state, to the suction passage 10d (suction port 30a). The returned fuel causes pressure pulsation in the suction passage 10. However, the suction passage 10c as a damper chamber provided in the suction passage 10 (formed between the cup-shaped damper cover 14 and the annular recess formed on the outer periphery of the pump body) has a corrugated plate shape. Two disk-shaped metal diaphragms are joined at their outer circumference, and a metal damper 9 injected with an inert gas such as argon is attached inside, and pressure pulsation is reduced by expansion and contraction of this metal damper 9. To be done.

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

  The fuel pressurized in the pressurizing chamber 11 passes through a hole 200h provided at the center of the relief valve stopper 200f, passes through a gap between the spirally wound relief valve springs 200c, and seat members (relief valve seat portion 200a, discharge valve seat portion). 8a) through the discharge passage 8e provided to the discharge valve 8b.

  In the discharge valve 8b of the discharge valve unit configured as described above, when there is no fuel pressure difference between the pressurizing chamber 11 and the high pressure passage 12, the discharge valve 8b is applied to the discharge valve seat portion 8a by the urging force of the discharge valve spring 8c. It is 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 8b opens against the discharge valve spring 8c, and the fuel in the pressurizing chamber 11 is discharged from the discharge valve holder. High-pressure discharge is performed 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 acts as a check valve that limits the flow direction of fuel.

  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 portion 200a of the relief valve body 200d is fixed by press-fitting (welding) the relief valve seat portion 200a side of the valve seat member S into one end opening portion of the tubular 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 tubular relief valve body 200d, and the relief valve spring stopper 200f is inserted into the tubular relief valve body. The interior member is held inside the tubular relief valve body 200d by being press-fitted and fixed to the inner periphery of 200d. The pressing force of 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 prescribed value by the pressing force of the relief valve spring 200c. Note that 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 tubular relief valve body 200d, and the valve seat member S is tubular. The relief valve body 200d can also be fixed to the opening at one end. At this time, the pressure can be adjusted by the press-fitting positions of the tubular relief valve body 200d and the valve seat member S.

  A discharge valve seat portion 8a is formed on the opposite side of the valve seat member S from the relief valve seat portion 200a, and the discharge valve seat portion 8a and the relief valve seat portion 200a are configured by one valve seat member S. The discharge valve seat 8S is composed of an annular protrusion formed on the outer edge of the end of the valve seat member S. By fitting the inner peripheral surface of the cup-shaped discharge valve holder 8d on the open end side 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 plate type discharge valve 8b are mounted inside the discharge valve holder 8d, and the discharge valve spring 8c is configured to press the flat plate type discharge valve 8b against an annular discharge valve seat 8S. ing.

  On the inner diameter side of the discharge valve seat 8S, one end is opened to the pressurizing chamber 11 side, and the other end 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 central portion. Specifically, one end of the discharge passage 8e is opened at a portion located radially outward from a center portion of the end portion of the valve seat member S on the pressurizing chamber 11 side where the relief passage 200gS is opened. Then, 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, which is located on the inner diameter side of the discharge valve seat 8a formed on the outer edge of the valve seat member S. There is. As a result, the discharge passage 8e is formed as a straight pipe passage that is inclined with respect to the central axis of the sheet member S in the longitudinal direction by the difference between the radial positions of the opening positions at both ends. Accordingly, the necessary 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 has a straight pipe portion 200gS whose one end is open to the relief valve seat portion 200S formed at the end of the valve seat member S on the pressure 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 portion of the relief valve body 200d, and is connected to the high pressure passage 12 through an 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 including the discharge valve mechanism 8 and the relief valve mechanism 200 which is unitized in this way is formed by pressing the outer periphery of the relief valve body 200d of the unit VU into the inner peripheral wall of the cylindrical opening 11A provided in the pump body 1. Fixed. Then, the discharge joint 12a is arranged 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 the high-pressure fuel to the common rail 23, and the high-pressure passage 12 is formed inside.

  In this way, by integrating the relief valve mechanism 200 with the discharge valve mechanism 8, the increase in the volume of the pressurizing chamber 11 can be suppressed to the minimum. Further, since the diameter of the relief valve mechanism 200 is smaller than the axial dimension, the relief valve mechanism 200 crosses the plunger 2 as in the present embodiment as compared with the case where the relief valve is arranged in the same direction as the plunger 2 of the high-pressure fuel supply pump. By arranging in the same direction, the dimension of the plunger 2 of the high-pressure fuel supply pump in the same reciprocating direction can be reduced.

  Further, since the fuel flowing from the pressurizing chamber 11 to the discharge valve mechanism 8 always passes through the inside of the relief valve mechanism 200, bubbles of air or vaporized fuel are likely to be discharged from the discharge valve 8a particularly at the time of engine startup. Prevents deterioration of compression function due to air bubbles. It also suppresses the occurrence of cavitation. That is, when the relief passage is formed at a position away from the discharge fuel passage as in the conventional case, when the bubbles of vaporized fuel stay in the relief passage, the bubbles are not removed until the relief valve opens, and the compression function is reduced. It was a cause of deterioration and cavitation. In the present embodiment, since the gas passes through the inside of the relief valve mechanism 200, that is, around the relief valve spring 200c and the ball valve holder 200e at the same time when the engine is started, the vaporized fuel bubbles accumulated in the portion of the relief valve mechanism 200 are promptly 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 body 1, the amount of passage machining of the pump body 1 can be reduced, and the productivity in terms of both machining and assemblability can be improved. Further, since the relief valve mechanism 200 and the discharge valve mechanism 8 can be incorporated in the automation line at the same time, the number of man-hours for the automation line is reduced.

  FIG. 4 shows an example of pressure waveforms at various portions when the fuel is normally pressurized to a high pressure by the high-pressure fuel supply pump and is being pressure-fed to the common rail 23. 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 upward, a pressure overshoot occurs in the pressurizing chamber 11 from the moment when the returning process shifts to the pressurizing process to immediately thereafter. 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 equal to or 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, the 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 the damage of the high-pressure passage portion including the common rail 23 due to the abnormal high pressure from the downstream side of the discharge valve mechanism 8 is installed in the discharge joint 12a of the high-pressure fuel supply pump, the flow rate due to the malfunction occurs. It is possible to obtain a high-pressure fuel supply pump that does not decrease and the volume efficiency does not decrease.

  Next, the case where an abnormally high pressure is generated in the high pressure passage portion 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. Then, when the pressure in the pressurizing chamber becomes higher than the pressure in the discharge channel, the discharge valve opens and the fuel is discharged from the pressurizing chamber to the discharge channel. From the moment the discharge valve opens to the moment immediately after, the pressure in the pressurizing chamber overshoots to a very high pressure.

  This high pressure also propagates in the discharge passage, and the pressure in the discharge passage also overshoots at the same timing.

  If the outlet of the relief valve is connected to the suction passage, the pressure difference between the inlet and outlet of the relief valve will be larger than the opening pressure of the relief valve due to the pressure overshoot in the discharge passage. And 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 passage is at the inlet of the relief valve. To work.

  Here, since pressure overshoots occur at the same timing in the pressurizing chamber and in the discharge passage, the pressure difference between the inlet and the 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 intake passage, fuel flows from the intake passage into the pressurizing chamber. To do. Then, when the volume of the pressurizing chamber starts to decrease due to the movement of the plunger again, the fuel is pressurized to a high pressure and discharged by the above mechanism.

  Here, if the fuel injection valve fails, that is, the injection function stops 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 gradually, an abnormality will be detected by the pressure sensor provided on the common rail, and the safety function that controls the displacement control mechanism provided in the suction passage to reduce the discharge amount will operate. High pressure cannot be dealt with by feedback control using this pressure sensor.

  Also, if the capacity control mechanism provided in the intake port or overflow passage fails and does not function as it was 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 abnormally high pressure cannot be eliminated because the capacity control mechanism itself is out of order.

  Further, when the injection of the injector is stopped after the engine is stopped or while the engine is running, it is usually possible that the fuel in the common rail will rise in pressure due to thermal expansion due to the heat on the engine side.

  When such an abnormally 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 inlet of the relief valve, that is, the discharge flow path becomes the pressure at the outlet of the relief valve, that is, the pressure of the pressurizing chamber. When the pressure exceeds the valve opening pressure of the relief valve, the valve opens, and the fuel having an abnormally high pressure in the discharge passage is returned to the pressurizing chamber. As a result, even when an abnormally high pressure is generated, the pressure does not exceed the specified high pressure, and the high-pressure piping system is 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 between the inlet and the outlet of the relief valve 102 is set by the mechanism described above during the discharge process. Since the above pressure difference does not occur, the relief valve does not open accidentally due to the peak pressure during the discharge process.

  In the suction process and the return process, the fuel pressure in the pressurizing chamber 11 drops to the same low pressure as the suction pipe 28. On the other hand, the pressure in the relief passage 200g has risen to the same pressure as the common rail 23. When the differential pressure between the relief passage 200g and the pressurizing chamber becomes equal to or higher than the valve opening pressure of the relief valve 200b, the relief valve 200b opens and the fuel having an abnormally high pressure is returned from the relief chamber 200b to the pressurizing chamber 11. The high-pressure pipes such as the common rail 23 are 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 relief valve opening pressure must be higher than that. If the valve opening pressure is set below that, the relief valve will open even if the fuel is normally pressurized by the high-pressure fuel supply pump. This malfunction of the relief valve causes a decrease in the discharge amount of the high-pressure fuel supply pump and a decrease in energy efficiency.

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

  However, when the relief spring is provided in the pressurizing chamber or the relief passage on the pressurizing chamber side, the relief spring becomes larger, and the volume of the pressurizing chamber or the volume of the chamber communicating with the pressurizing chamber increases accordingly. Will be done.

  Since the high-pressure fuel supply pump reduces the volume in the pressurizing chamber by the movement of the plunger and compresses the fuel to pressurize and discharge the fuel to a high pressure, the increase in the volume of the pressurizing chamber is correspondingly large. Since the fuel must be pressurized to a high pressure, there is a problem that the high-pressure fuel supply pump causes a reduction in compression rate and a reduction in energy efficiency.

  Furthermore, it becomes impossible to pressurize the fuel required for the internal combustion engine to a high pressure. In this embodiment, the increase of the volume of the pressurizing chamber can be minimized by integrating the discharge valve and the relief valve.

  Further, since the fuel flowing from the pressurizing chamber 11 to the discharge valve always passes through the inside of the relief valve mechanism, bubbles of air or vaporized fuel are likely to be discharged from the discharge valve, especially when the engine is started, and the compression function by the bubbles is achieved. Can be prevented.

  The 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 in FIG. 3 of the first embodiment, and the relief valve spring 200c is received by the bottom surface integrally formed with the relief valve body 200d.

  The relief valve seat portion 200a (a component integrated with the discharge valve seat portion 8a) is fixed to the relief valve body 200d by press fitting or the like. 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 side of the discharge valve mechanism 8 and the low-pressure fuel passage upstream of the intake valve 32 is provided, and the second relief passage is higher than the operation set pressure of the relief valve mechanism 200 described above. If a second relief valve mechanism with a set pressure is installed, a safer system can be obtained.

  The orifice 200Y shown in FIG. 4 is for damping 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 of solving the following problems of the prior art.
(1) Since the relief valve mechanism is installed in the pressurizing chamber or a passage leading to the pressurizing chamber, the volume of the pressurizing chamber becomes large and the compression efficiency decreases.
(2) Furthermore, the spring mechanism part of the relief valve connected to the pressurizing chamber becomes a blind alley, making it difficult for air or vaporized fuel bubbles to escape, further reducing the compression function.

  In the present embodiment, even if a relief valve mechanism that returns abnormally high pressure fuel in the high pressure passage to the pressurizing chamber is installed in the pump body, the bubbles in the compression chamber are well removed, and the compression efficiency is high, that is, the energy efficiency is high, and the boosting pressure is high. A high-pressure fuel pump with high capacity can be provided.

  According to the present embodiment, when an abnormally high pressure is generated 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 become abnormal. It is possible to provide a high-pressure fuel pump having a high compression rate, that is, energy efficiency, while maintaining the effect of not being damaged by high pressure.

  The mode of implementation of this example is summarized as follows.

[Embodiment 1]
In a high-pressure fuel supply pump including 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 set so that fuel from the pressurizing chamber flows through the relief valve mechanism to the discharge valve.

[Embodiment 2]
In what is described in Embodiment 1,
The high-pressure fuel supply pump, wherein the discharge valve seat and the relief valve seat are formed by one component.

[Embodiment 3]
In what is described in Embodiment 1,
A high-pressure fuel supply pump, wherein one or more passages to the discharge valve seat are formed in the discharge valve seat or the relief valve seat.

[Embodiment 4]
In what is described in Embodiment 1,
A high-pressure fuel supply pump, wherein one or more passages to the relief valve discharge valve seat are formed in the discharge valve seat or the relief valve seat.

[Embodiment 5]
In what is described in Embodiment 1,
A 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,
A high-pressure fuel supply pump, wherein an assembly unit of the relief valve mechanism and the discharge valve mechanism is mounted from inside the pressurizing chamber.

[Embodiment 7]
In what is described in embodiment 5,
A high-pressure fuel supply pump, wherein the 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,
A high-pressure fuel supply pump, characterized in that 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]
In what is described in Embodiment 1,
A high-pressure fuel supply pump, wherein the relief passage opens to a side peripheral surface of the pressurizing chamber.

[Embodiment 11]
In what is described in Embodiment 1,
A high-pressure fuel supply pump, wherein the return passage opens to the top surface of the pressurizing chamber.

[Embodiment 12]
In what is described in Embodiment 1,
A plurality of the relief passages provided with the relief valve mechanism are provided,
A high-pressure fuel supply pump, wherein at least one of the relief passages has an outlet opening to a low-pressure passage.

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

[Embodiment 14]
In what is described in Embodiment 1,
A high-pressure fuel supply pump, wherein the valve drive mechanism includes an electromagnetic drive mechanism.

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

  The capacity control mechanism is not affected by the model or installation position of the capacity control mechanism, and can be implemented by any type of capacity control mechanism.

1 Pump body 2 Plunger 8 Discharge valve mechanism 11 Pressurizing chamber 24 Injector 30 Electromagnetic suction valve 200 Relief valve mechanism 200b Relief valve 200g Relief passage

Claims (7)

A discharge valve mechanism provided on the discharge side of the pressurizing chamber, a high pressure passage provided on the downstream side of the discharge valve mechanism, and a relief valve opened due to a pressure difference between the high pressure passage and the pressurizing chamber, and the high pressure passage side. A common one having a relief valve mechanism for returning the fuel to the pressurizing chamber, a discharge valve seat portion against which the discharge valve of the discharge valve mechanism is pressed, and a relief valve seat portion against which the relief valve of the relief valve mechanism is pressed. And two valve seat members,
The relief valve mechanism, the discharge valve mechanism, and the valve seat member are configured as one unit,
The relief valve mechanism includes a relief valve spring that presses the relief valve against the relief valve seat portion,
The high-pressure fuel supply pump, wherein the load of the relief valve spring is adjusted by the mounting depth of the valve seat member with respect to the relief valve body of the relief valve mechanism provided on the outer peripheral side of the relief valve spring. A discharge valve mechanism provided on the discharge side of the pressurizing chamber, a high pressure passage provided on the downstream side of the discharge valve mechanism, and a relief valve opened due to a pressure difference between the high pressure passage and the pressurizing chamber, and the high pressure passage side. A common one having a relief valve mechanism for returning the fuel to the pressurizing chamber, a discharge valve seat portion against which the discharge valve of the discharge valve mechanism is pressed, and a relief valve seat portion against which the relief valve of the relief valve mechanism is pressed. And two valve seat members,
The relief valve mechanism, the discharge valve mechanism, and the valve seat member are configured as one unit,
The relief valve mechanism includes a relief valve spring that presses the relief valve against the relief valve seat portion,
The load of the relief valve spring is adjusted by the mounting depth of the relief valve spring stopper of the relief valve mechanism that receives the relief valve spring ,
A first relief passage formed on the inner diameter side of the valve seat member and communicating with the downstream side of the relief valve mechanism, and a second relief passage branching radially outward from the first relief passage to communicate with the high pressure passage. A high-pressure fuel supply pump that forms a relief passage in the valve seat member so that the high-pressure passage communicates with the downstream side of the relief valve mechanism via the relief valve mechanism . The high-pressure fuel supply pump according to claim 1,
A high-pressure fuel supply pump, wherein a bottom surface for receiving the relief valve spring is integrally formed with the relief portion body. The high-pressure fuel supply pump according to claim 1,
A high-pressure fuel supply pump, wherein a relief valve spring stopper that receives the relief valve spring is fixed to an inner circumference of the relief valve body. The high-pressure fuel supply pump according to any one of claims 1 to 3 ,
A first relief passage formed on the inner diameter side of the valve seat member and communicating with the downstream side of the relief valve mechanism, and a second relief passage branching radially outward from the first relief passage to communicate with the high pressure passage. A high-pressure fuel supply pump that forms a relief passage in the valve seat member so that the high-pressure passage communicates with the downstream side of the relief valve mechanism via the relief valve mechanism. The high-pressure fuel supply pump according to claim 5,
A plurality of discharge passages, one end of which is open to the pressurizing chamber side and the other end of which is open to the inner diameter side of the discharge valve seat portion, are formed in the valve seat member,
The high-pressure fuel supply pump, wherein the plurality of discharge passages are formed to be inclined with respect to the axial direction of the valve seat member so as to avoid the first relief passage and the second relief passage. The high-pressure fuel supply pump according to any one of claims 1 to 4,
The discharge valve mechanism includes a discharge valve spring for pressing the discharge valve against the discharge valve seat portion, and the discharge valve holder provided on the outer peripheral side of the discharge valve spring,
A high-pressure fuel supply pump in which the inner peripheral surface of the discharge valve holder is fitted and fixed to the outer peripheral surface of the valve seat member.

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