JP2010185459A - High-pressure fuel pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-pressure fuel pump capable of reducing pressure pulsation in low-pressure piping caused by operation of the high-pressure fuel pump. <P>SOLUTION: In the high-pressure fuel pump, an inlet auxiliary chamber whose volume varies through reciprocation of a plunger is provided on an opposite side of a compression chamber. An accumulator is disposed in a fuel inlet passage between the inlet valve and the inlet side pipe line. The inlet auxiliary chamber and the compression chamber are connected to the inlet side pipe line via the accumulator. With this structure, the accumulator can effectively reduce pulsation of fuel returning from the compression chamber to the inlet passage, pulsation of fuel flowing from the inlet auxiliary chamber to the inlet passage, and pulsation flowing from a low-pressure pipe to the accumulator. This can prevent the pulsation from being easily transmitted to the low-pressure piping. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a plunger-type high-pressure fuel pump used in a fuel supply system for an internal combustion engine, and more particularly to a plunger-type high-pressure fuel pump that can effectively reduce pressure pulsation in a low-pressure pipe.

  In recent years, direct injection engines (in-cylinder injection internal combustion engines) have been developed for the purpose of improving the exhaust emission and fuel consumption of automobiles from the viewpoint of environmental conservation. This in-cylinder injection internal combustion engine is an internal combustion engine of a type in which fuel injection by a fuel injection valve is directly performed in a combustion chamber of a cylinder, and by reducing the particle size of fuel injected from the fuel injection valve, the injected fuel Combustion is promoted to reduce specific substances in exhaust gas and improve fuel efficiency.

  Here, in order to reduce the particle size of the fuel injected from the fuel injection valve, means for increasing the pressure of the fuel is required. For this reason, a high-pressure fuel pump that pumps high-pressure fuel to the fuel injection valve is required. A technique has been proposed (see, for example, Patent Document 1).

  In the technique described in Patent Document 1, when the flow control of the high-pressure fuel supplied according to the fuel injection amount of the fuel injection valve is performed, the driving force of the high-pressure fuel pump is reduced and the flow control valve does not operate. It also supplies fuel. Two types of intake valves, normally open and normally closed, are described as flow control mechanisms. In either case, high-pressure fuel is controlled by manipulating the timing at which the intake valve closes during the discharge process. The volume of the fuel pressurized by the pump is adjusted.

JP 2000-8997 A

  However, since the above-described high-pressure fuel pump repeats intermittent intake and discharge of fuel, pressure pulsation occurs in the upstream and downstream pipes. For example, on the low-pressure pipe side, the high-pressure pump supplies fuel to the pressurizing chamber. The pressure decreases when sucked into the fuel, and the pressure increases when the pressure chamber returns to the fuel inlet side.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a high-pressure fuel pump that can reduce pressure pulsation in low-pressure piping caused by the operation of the high-pressure fuel pump. .

  In order to achieve the above object, the high-pressure fuel pump of the present invention is provided with a suction sub chamber whose volume changes as the plunger reciprocates on the side opposite to the pressurizing chamber, and a suction valve, a suction side pipe line, An accumulator was provided in the fuel suction passage between the suction sub chamber and the suction sub chamber and the pressurizing chamber.

  According to the present invention configured as described above, the pulsation of fuel returning from the pressurizing chamber to the suction passage by the accumulator, the pulsation of fuel flowing from the suction subchamber, and the pulsation of fuel flowing from the low-pressure pump to the accumulator are effective. These pulsations can be hardly transmitted to the low-pressure piping.

1 is an overall configuration diagram of a fuel supply system for an internal combustion engine according to an embodiment of the present invention. The timing chart which shows the flow velocity change of the plunger pump in this invention. Schematic which shows the flow of the fuel in 0% discharge mode. Schematic which shows the flow of the fuel in 100% discharge mode. The graph which shows the relationship between volume ratio and flow velocity difference (DELTA) Q. Another embodiment to which the present invention is applied.

[Example 1]
Examples of the present invention will be described below.
First, the configuration of a fuel supply system using a plunger-type high-pressure fuel pump, which is a variable displacement fuel pump according to this embodiment, will be described with reference to FIG. A fuel suction passage 10, a discharge passage 11, and a pressurizing chamber 12 are formed in the pump body 1. A plunger 2 as a pressurizing member is slidably held in a cylinder portion 63 inside the pump body 1. The plunger 2 has a small diameter portion 2 a and a large diameter portion 2 b, and the large diameter portion 2 b forms a part of the pressurizing chamber 12. As the plunger 2 reciprocates according to the rotating cam 100, the volume of the pressurizing chamber 12 changes. A suction valve 5 is provided in the fuel suction passage 10 and a discharge valve 6 is provided in the discharge passage 11, each of which serves as a check valve that restricts the direction of fuel flow by a structure that is held in one direction by a spring. The electromagnetic actuator 8 is held by the pump body 1 and includes a solenoid coil 90, a rod 91, and a spring 92. A biasing force is applied to the rod 91 in a direction in which the intake valve 5 is opened by the spring 92 in a state where a drive signal is not applied to the electromagnetic actuator 8. Since the biasing force of the spring 92 is set to be larger than the biasing force of the spring of the suction valve 5, the suction valve 5 is in an open state as shown in FIG. Become.

  A seal member 60 is slidably contacted with the small diameter portion 2a of the plunger 2, and the seal member prevents the fuel in the suction sub chamber 61 from leaking to the cam 100 side. As the plunger 2 reciprocates, the volume of the suction sub chamber 61 changes. The communication channel 62 communicates the suction sub chamber 61 and the fuel suction passage 10 and allows fuel to pass as the suction sub chamber 61 increases or decreases.

  The fuel drawn from the tank 50 by the low pressure pump 51 is adjusted to a constant pressure by the pressure regulator 52 and guided to the fuel inlet of the pump body 1. The fuel pressurized by the pump body 1 is pumped to the common rail 53 from the fuel discharge port. An injector 54, a pressure sensor 56, and a safety valve 58 are attached to the common rail 53. The safety valve 58 opens when the fuel pressure in the common rail 53 exceeds a predetermined value, and prevents damage to the high-pressure piping system. The injectors 54 are installed according to the number of cylinders of the engine, and inject fuel by a signal from the controller 57. The pressure sensor 56 sends the acquired pressure data to the controller 57.

  The controller 57 calculates an appropriate amount of fuel to be injected, fuel pressure, etc. based on engine state quantities (crank rotation angle, throttle opening, engine speed, fuel pressure, etc.) obtained from various sensors. The timing and flow rate for driving 54 are calculated and a drive signal is output. In the controller 57, there are cases where the host controller that calculates the command value and the controller that directly outputs the drive signal to the pump / injector are separate units. Also good.

  The plunger 2 reciprocates according to the cam 100 rotated by an engine camshaft or the like to increase or decrease the volumes of the pressurizing chamber 12 and the suction sub chamber 61. When the plunger 2 moves upward in FIG. 1, the volume of the pressurizing chamber 12 decreases and the volume of the suction sub chamber 61 increases. On the other hand, when the plunger 2 moves downward in FIG. 1, the volume of the pressurizing chamber 12 increases and the volume of the suction subchamber 61 decreases. The pressurizing chamber 12 and the suction sub chamber 61 are connected via a communication channel 62, and the fuel sucked into the pressurizing chamber 12 or a part of the fuel discharged from the chamber 12 is discharged from the suction sub chamber 61. The fuel is structured to be the fuel to be sucked or the fuel sucked into the chamber 61. For this reason, the amount of fuel flowing into or out of the fuel intake passage 10 is configured to be smaller than the amount of fuel sucked into or discharged from the pressurization chamber 12. Yes.

  If the electromagnetic actuator 8 is operated during the discharge process of the plunger 2 to close the suction valve 5, the pressure in the pressurizing chamber 12 rises, whereby the discharge valve 6 is automatically opened and the fuel is supplied to the common rail 53. To pump. The suction valve 5 is automatically opened when the pressure in the pressurizing chamber 12 becomes lower than the fuel inlet, but the closing is determined by the operation of the electromagnetic actuator 8.

  When a drive signal is given from the controller 57, the electromagnetic actuator 8 generates a magnetic field by causing a current to flow through the solenoid coil 90 and pulls the rod 91 biased by the spring 92. Then, since the engagement between the suction valve 5 and the rod 91 is released, the suction valve 5 becomes an automatic valve that opens and closes in synchronization with the reciprocating motion of the plunger 2. That is, during the discharge process, the suction valve 5 is closed, and the fuel corresponding to the volume reduction of the pressurizing chamber 12 is pushed and opened to the common rail 53 by pushing the discharge valve 6 open.

  On the other hand, in a state where a drive signal is not applied to the electromagnetic actuator 8, the rod 91 is engaged with the suction valve 5 by the biasing force of the spring 92, and the suction valve 5 is held in the open state. This pressure is maintained at a low pressure almost equal to that of the fuel inlet even during the discharge process, and the discharge valve 6 cannot be opened. As a result, the fuel corresponding to the volume reduction of the pressurizing chamber 12 is returned to the fuel introduction port side through the suction valve 5, and the pump discharge flow rate to the discharge passage can be made zero.

  When a drive signal is given to the electromagnetic actuator 8 in the middle of the discharge process, the rod 91 is displaced, the engagement with the intake valve 5 is released, the valve 5 is closed, and fuel is supplied to the common rail 53 from the middle of the discharge process. Pumping is started. Once the pumping starts, the pressure in the pressurizing chamber 12 has increased. Therefore, even if the drive signal for the electromagnetic actuator 8 is turned off after that, the suction valve 5 remains closed and is synchronized with the start of the next suction process. And automatically opens the valve. In this way, by adjusting the timing for supplying the drive signal to the electromagnetic actuator 8, the pump discharge flow rate can be variably adjusted within the range of 0 to the maximum discharge amount.

  Further, the pressure of the common rail 53 can be maintained at a substantially constant value by calculating an appropriate discharge timing by the controller 57 based on the signal from the pressure sensor 56 and giving a drive signal to the electromagnetic actuator 8.

  Here, the reciprocating motion of the plunger 2 causes the fuel to be sucked in or discharged from the fuel suction passage 10, so that pressure pulsation occurs in the fuel suction passage 10 and the upstream piping. When the pressurizing chamber 12 sucks fuel, the suction subchamber 61 discharges the fuel and reduces the flow rate of the fuel flowing into the fuel suction passage 10, and as a result, the fuel suction flow path and the upstream pipe pressure decrease. Reduce. In addition, when the pressurizing chamber 12 discharges fuel, the suction subchamber 61 reduces the flow rate of the fuel that sucks in the fuel and flows out of the fuel suction passage 10, and increases the pressure in the fuel suction passage and its upstream side. Reduce. The suction subchamber has a function that contributes to reduction of pulsation on the fuel suction passage 10 and its upstream side based on the principle described above.

Next, the pulsation reducing effect exhibited by the present invention will be described with reference to FIG.
FIG. 2 shows an example of a drive timing chart of the high-pressure fuel pump in the present invention. 2 indicates the operation of the plunger 2 in FIG. The ascending process indicates a pressurizing process, and the descending process indicates an inhaling process. The “pressurization chamber flow velocity” in the second stage in FIG. 2 indicates the flow velocity (unit: m ³ / s, etc.) of the fuel flowing out / inflow from the pressurization chamber 12 to the low pressure side. When the pump drive signal is not given, the fuel flows out from the pressurizing chamber while the plunger 2 is raised, and the fuel flows into the pressurizing chamber while the plunger 2 is lowered.

  A “pump drive signal” shown in the fourth row in FIG. 2 indicates a signal for driving the electromagnetic actuator 8. When the pump drive signal is given at a certain timing, the rod 91 is displaced to release the engagement of the suction valve 5, and the suction valve 5 is closed at the timing of "suction valve displacement" shown in the fifth stage of FIG. I speak. As a result, the fuel in the pressurizing chamber 12 is discharged to the high pressure side. On the other hand, before the intake valve 5 is closed, the fuel is discharged to the low pressure side. By changing the timing at which the pump drive signal is applied, the timing at which the intake valve 5 is closed can be changed, and the amount of fuel discharged to the high pressure side can be adjusted. As a result, the amount of fuel discharged to the low pressure side also changes. The “suction sub chamber flow velocity” in the third stage in FIG. 2 indicates the flow velocity of the fuel flowing in / out of the suction sub chamber 61. Since the increase / decrease in the volume of the suction sub-chamber 61 is in the opposite phase to the increase / decrease in the pressurization chamber 12, as shown in the drawing, the increase / decrease direction of the suction sub-chamber flow velocity is opposite to that of the pressurization chamber flow velocity.

  The “suction passage flow velocity” in the sixth stage in FIG. 2 indicates the flow velocity of the fuel that finally enters and exits the fuel suction passage 10. When the suction passage flow velocity is positive, that is, when fuel flows into the suction passage 10, the fuel pressure in the suction passage 10 increases. The suction passage flow velocity is the sum of the pressurization chamber flow velocity shown in the second stage of FIG. 2 and the suction sub-chamber flow velocity shown in the third stage. Before the suction valve 5 is closed in the discharge process, fuel flows out from the pressurizing chamber 12 and part of the fuel flows into the suction sub chamber 61. Therefore, the amount of fuel flowing out into the fuel suction passage 10 is the difference between the amount flowing out from the pressurizing chamber 12 and the amount flowing into the suction sub chamber. On the other hand, after the intake valve 5 is closed, the pressurizing chamber 12 is shut off from the fuel intake passage 10 by the intake valve 5, so that only the fuel sucked by the intake subchamber 61 is sucked from the fuel intake passage 10. . The difference between the maximum value and the minimum value of the suction passage flow velocity is defined as ΔQ. The larger this ΔQ, the larger the pressure pulsation on the low-pressure pipe side, and this can be used as an evaluation index of pulsation.

Next, the operation mode of the pump will be described with reference to FIGS. 3 and 4.
The fuel flow in the suction and discharge process when the pump discharge amount is 0% is shown in FIGS. 3a and 3b. In the suction process shown in FIG. 3 a, the fuel flows out from the suction subchamber 61 at the same time as the fuel flows into the pressurizing chamber 12. At this time, the flow rate of the fuel flowing in from the fuel suction passage 10 is the difference between the flow rate into the pressurizing chamber 12 and the flow rate from the suction sub chamber 61. On the other hand, at the time of the discharge process shown in FIG. 3B, all the fuel in the pressurizing chamber 12 flows out to the low pressure side, and at the same time, the fuel flows into the suction sub chamber 61. At this time, the flow rate of the fuel flowing out into the fuel suction passage 10 is the difference between the flow rate from the pressurizing chamber 12 and the flow rate into the suction sub chamber 61.

  FIGS. 4a and 4b show the fuel flow in the suction and discharge processes when the pump discharge amount is 100%. At the time of the suction process shown in FIG. 4a, the fuel flows out from the suction subchamber 61 at the same time as the fuel flows into the pressurizing chamber 12, as in the case of 0% discharge. On the other hand, in the discharge process shown in FIG. 4B, the fuel in the pressurizing chamber 12 is discharged to the discharge passage 11 side. Therefore, only the fuel sucked by the suction sub chamber 61 flows out from the fuel suction passage 10 on the low pressure side.

  Next, the displacement volume of the pressurizing chamber 12 and the suction subchamber 61 that can reduce the pulsation on the low-pressure piping side most effectively will be described using mathematical expressions. That is, the relationship of the volume that minimizes the flow rate difference ΔQ will be described. As described above, the flow velocity in the fuel intake passage 10 varies depending on the operation mode of the pump. Since the high-pressure fuel pump of the present invention is a variable displacement type, there is an optimum value in consideration of each operation mode.

Assuming that the cross-sectional area of the large-diameter portion of the plunger 2 is A ₁ and the cross-sectional area of the small-diameter portion is A ₂ , the cross-sectional area A ₃ that contributes to the displacement volume of the suction sub chamber 61 is (Equation 1).

The maximum flow rate Q _in of the fuel flowing into the fuel intake passage 10 during the intake process is expressed by (Expression 2), where v is the maximum speed of the plunger 2 during the intake process.

Maximum flow rate Q _out of the fuel flowing into the fuel inlet passage 10 during the discharge process varies by the discharge mode. In the 0% discharge mode, when the maximum speed of the plunger 2 at the time of the discharge process is v, it is expressed by (Equation 3).

On the other hand, in the 100% discharge mode, maximum flow rate _{Q out} of the fuel flowing into the fuel inlet passage 10 during the discharge process is represented by the equation (4).

The flow velocity difference ΔQ of the fuel flowing into and out of the fuel intake passage 10 can be obtained by subtracting the minimum value from the maximum values of Q _in and Q _out . The flow rate difference ΔQ in the 0% discharge mode is obtained by subtracting (Equation 2) from (Equation 3).

Further, the flow rate difference ΔQ in the 100% discharge mode is the larger one of (Equation 2) and (Equation 4).

FIG. 5 shows a graph in which the flow rate difference in the 0% discharge mode (Equation 5), the flow rate difference in the 100% discharge mode (Equation 6), and the maximum values thereof are superimposed. In the case of 0% ejection, ΔQ tends to decrease as the volume ratio (A ₃ / A ₁ ) approaches 1. On the other hand, in the case of 100% ejection, ΔQ takes the minimum value when the volume ratio (A ₃ / A ₁ ) is 0.5. That is, it can be seen that even if ΔQ of the 100% discharge mode is reduced at a certain volume ratio (A ₃ / A ₁ ), the 0% discharge mode may not be reduced. When examining the volume ratio (A ₃ / A ₁ ) that minimizes ΔQ in the entire region from 0% discharge to 100% discharge, it is necessary to obtain the minimum value of the maximum values of (Equation 5) and (Equation 6). That is, the minimum value of (Expression 7) is obtained.

The minimum value of the above (Expression 7) makes ΔQ minimum at the position where the thick solid line is bent in FIG. 5, that is, at the volume ratio (A ₃ / A ₁ ) = 2/3. That is, when the ratio of the displacement volume of the suction sub chamber 61 and the pressurizing chamber 12 is 2: 3, theoretically, the pressure pulsation of the low pressure pipe can be minimized.

となる。すなわち、プランジャ２の小径部分と大径部分の断面積の比率を１：３とする時、理論上、低圧配管の圧力脈動を最小とすることができる。 And at this theoretical optimum point, the cross-sectional area A ₂ of the small diameter portion is given by (Equation 1)

It becomes. That is, when the ratio of the cross-sectional area of the small diameter portion and the large diameter portion of the plunger 2 is 1: 3, theoretically, the pressure pulsation of the low pressure pipe can be minimized.

  However, since the above ratio is a numerical value that is theoretically derived, if this value is approximately this value, a pulsation characteristic close to the minimum value can be obtained, and therefore it is not always necessary to accurately set this value. The ratio of the displacement volume of the suction sub chamber 61 and the pressurizing chamber 12 is described as optimal at 2: 3, but if it is approximately 2: 3, the pulsation characteristic close to the minimum value can be obtained, and similarly If the cross-sectional area ratio between the small diameter portion and the large diameter portion of the plunger 2 is also approximately 1: 3, a pulsation close to the minimum value can be obtained.

  Finally, the detailed structure of a variable displacement fuel pump according to another embodiment to which the present invention is applied will be described with reference to FIG. The plunger 2c is slidably held by a cylinder 63c at the large diameter portion 2e. The pressurizing chamber 12c is formed by the pump body 68c, the plunger 2c, and the like. The cylinder 63c is pressed against the pump body 68c by the cylinder holder 64c. The cylinder holder 64c is pressed against the cylinder holder 64c by the flange holder 66c. The flange holder 64c is fixed to the pump body 68c by screws or press-fitting and presses the flange holder 64c. A seal member 60c is slidably contacted with the small diameter portion 2d of the plunger 2c, and the seal member 60c is fixed to the cylinder holder 64c.

  A suction sub chamber 61c is formed by the cylinder holder 64c, the plunger small diameter portion 2d, and the seal member 60c. The fuel in the suction sub chamber 61c is sealed from external leakage by the seal member 60c and the O-ring 67c. The suction sub chamber 61c communicates with the fuel suction passage 10c through the communication channel 62c. A throttle portion 70c is formed in a part of the communication channel 62c by a part of the cylinder 63c and the cylinder holder 64c. A pulsation absorbing chamber 69c is provided between the fuel suction passage 10c and the pressurizing chamber 12c, and an accumulator 65c is installed there. A suction valve 5c is provided between the pulsation absorbing chamber 69c and the pressurizing chamber 12c to limit the fuel flow direction. The opening / closing operation of the intake valve 5c is controlled by the actuator 8c. Although omitted in FIG. 6, a discharge valve is provided between the pressurizing chamber 12c and the discharge passage.

  When the plunger 2c reciprocates, the volume in the suction sub chamber 61c increases and decreases, and the fuel flows into and out of the pulsation absorption chamber 69c through the communication flow path 62c. On the other hand, fuel also flows into and out of the pulsation absorbing chamber from the pressurizing chamber 12c. These fuel inflows and inflows are subtracted in the pulsation absorption chamber 12c, and the surplus contributes to the generation of pressure pulsation, but the pulsation is reduced by the accumulator 65c. Providing an orifice, choke, or the like in the fuel intake passage 10c is more desirable because it can reduce the propagation of the pressure pulsation in the pulsation absorption chamber 69c to the upstream pipe (low pressure pipe).

  As can be understood from the above description, the plunger type high-pressure fuel pump according to this embodiment is provided with a suction sub chamber whose volume is changed by the reciprocating movement of the plunger on the side opposite to the pressurizing chamber, and A fuel that is provided with a passage that communicates the sub chamber and the suction side pipe line, and preferably has a volume ratio of the suction sub chamber and the pressurization chamber of 2: 3, so that the fuel is sucked or discharged between the pressurization chamber and the suction passage. By effectively canceling out the fuel discharged or sucked between the suction sub chamber and the suction passage, the pressure pulsation of the low-pressure pipe communicating with the suction passage can be reduced.

The aspects of the above embodiment are summarized as follows.
The high-pressure fuel pump of the present embodiment is formed by a cylinder provided in the pump housing, a plunger slidably provided in the cylinder and reciprocating according to a rotating cam, and the plunger and the cylinder. A pressurizing chamber; a suction valve that opens and closes between the pressurizing chamber and the suction side pipe; a discharge valve that opens and closes between the pressurization chamber and the discharge side pipe; and an actuator that controls opening and closing of the suction valve A plunger-type high-pressure fuel pump having a suction sub chamber whose volume is changed by reciprocating movement of the plunger on the opposite side of the plunger from the pressurizing chamber, and communicating the suction sub chamber with the suction side pipe line. Provide a passage. By doing so, the plunger reciprocates and the fuel is sucked and discharged into the pressurizing chamber, and at the same time, the fuel is discharged and sucked into the suction subchamber. Reduce.

  More preferably, in the plunger type high-pressure fuel pump, the ratio of the displacement volume between the suction sub chamber and the pressurizing chamber is approximately 2: 3. Although details will be described later, by doing so, the fuel flow velocity to the low-pressure pipe is theoretically minimized in the entire operation mode of the pump, and the pressure pulsation of the low-pressure pipe can be effectively reduced.

  Alternatively, a cylinder provided in the pump housing, a plunger slidably provided in the cylinder and reciprocating according to a rotating cam, a pressurization chamber formed by the plunger and the cylinder, and pressurization A plunger-type high-pressure fuel pump comprising a suction valve that opens and closes between the chamber and the suction side pipe, a discharge valve that opens and closes between the pressurization chamber and the discharge side pipe, and an actuator that opens and closes the suction valve The plunger is formed of a large-diameter portion and a small-diameter portion, and a seal member is provided in sliding contact with the small-diameter portion, and a suction sub chamber formed by the small-diameter portion of the plunger and the seal member is provided. The plunger type high-pressure fuel pump is provided with a passage communicating between the chamber and the suction side pipe line.

  In this way, the suction sub chamber can be constituted by the small diameter portion of the plunger and the seal member, and the amount of leakage from the seal member can be reduced by reducing the diameter of the seal member.

  More preferably, the ratio of the cross-sectional area of the small diameter portion and the large diameter portion of the plunger is approximately 1: 3. By doing so, the ratio of the displacement volume of the suction sub chamber and the pressurizing chamber becomes approximately 2: 3, and the pressure pulsation of the low pressure pipe can be effectively reduced as described above.

  More preferably, a throttle portion such as an orifice is provided in a passage communicating between the suction sub chamber and the suction side pipe line. This makes it difficult for fuel to escape into the suction subchamber during the pump discharge process, and lowers the pressure in the suction subchamber. Then, in the next inhalation step, the plunger is sucked toward the inhalation subchamber side and is difficult to jump.

  More preferably, an accumulator is provided between the suction side pipe line and the suction valve. By doing so, the flow rate fluctuation entering and exiting the suction side conduit as described above is reduced, and the pressure pulsation can be absorbed before the accumulator propagates to the suction side conduit.

  In the plunger type high-pressure fuel pump configured as described above, the pressure pulsation in the low-pressure pipe is reduced by effectively canceling out the amount of fuel returning from the pressurization chamber to the low-pressure pipe into the suction sub-chamber. Can do.

  The present embodiment is effective for reducing pulsation in the entire region from a low engine load state to a high engine load state, that is, from a low fuel discharge amount to a high fuel discharge amount. Although the pressure pulsation of the low-pressure pipe may have a resonance point depending on the engine speed, the pressure pulsation can be reduced in any situation by minimizing the flow rate fluctuation from the inside of the pump, which becomes the excitation force. In addition, since the flow rate fluctuation inside the pump is reduced, there is a margin for lowering the performance of the accumulator. That is, the accumulator can be reduced in size and simplified. Further, since the fuel seal is performed at the small diameter portion of the plunger, the seal area is reduced as compared with the case where the fuel seal is performed at the large diameter portion. In the present invention, the ratio of the displacement volume between the suction sub chamber and the pressurizing chamber is set to 2: 3, but an equivalent pulsation reducing effect can be obtained as long as the ratio is substantially close thereto.

1 High-pressure fuel pump (main unit)
2 Plunger 2a Plunger small diameter portion 2b Plunger large diameter portion 3 Tappet 5 Suction valve 6 Discharge valve 8 Electromagnetic actuator 10 (Fuel) Suction passage 11 Discharge passage 12 Pressurization chamber 61 Suction subchamber 62 Communication flow passage 90 Solenoid coil 91 Rod 92 Spring 100 cams

Claims (9)

A pressurizing chamber provided in the pump housing;
A plunger that reciprocates according to a rotating cam;
A suction valve that opens and closes between the pressurizing chamber and the suction side pipe;
A discharge valve for opening and closing between the pressurizing chamber and the discharge side pipe line;
An actuator for controlling opening and closing of the suction valve;
A suction subchamber that is provided on the opposite side of the plunger from the pressurizing chamber, and whose volume changes as the plunger reciprocates;
A pulsation absorbing chamber provided in a fuel suction passage between the suction valve and the suction side pipe;
An accumulator provided in the pulsation absorption chamber,
A plunger type high-pressure fuel pump in which the suction sub chamber and the pressurizing chamber are connected to the suction side pipe line via the pulsation absorption chamber. A pressurizing chamber provided in the pump housing;
A plunger that reciprocates according to a rotating cam;
A suction valve that opens and closes between the pressurizing chamber and the suction side pipe;
A discharge valve for opening and closing between the pressurizing chamber and the discharge side pipe line;
An actuator for controlling opening and closing of the suction valve;
A suction subchamber that is provided on the opposite side of the plunger from the pressurizing chamber, and whose volume changes as the plunger reciprocates;
A pulsation absorbing chamber provided in a fuel suction passage between the suction valve and the suction side pipe;
An accumulator provided in the pulsation absorption chamber,
The suction side conduit is connected to the pulsation absorption chamber, and thus fuel from the suction side conduit passes through the periphery of an accumulator provided in the pulsation absorption chamber, and the volume of the pressurization chamber increases, Fuel flows from the pulsation absorption chamber through the suction valve into the pressurization chamber, and if the suction valve is open when the volume of the pressurization chamber decreases, fuel flows from the pressurization chamber to the pulsation absorption chamber through the suction valve. return,
When the volume in the suction subchamber increases, the fuel in the pulsation absorption chamber flows out from the pulsation absorption chamber to the suction subchamber through the communication channel, and the communication in the communication due to the decrease in the volume in the suction subchamber. A plunger type high-pressure fuel pump in which fuel in the suction subchamber flows into the pulsation absorption chamber from the suction subchamber through a flow path. In one of claim 1 or claim 2,
The plunger is formed of a large-diameter portion and a small-diameter portion, and the small-diameter portion has a seal member that is in sliding contact with the outer periphery of the plunger,
The suction subchamber is formed by the small diameter portion of the plunger and the seal member;
A plunger-type high-pressure fuel pump, wherein a communication flow path communicating the suction sub chamber and the accumulator is formed along a longitudinal direction of the plunger. In one of claims 1 to 3,
A plunger-type high-pressure fuel pump in which a communication channel that communicates the pressurizing chamber and the accumulator is formed along the longitudinal direction of the plunger. In what was described in any one of Claims 1-4,
A plunger type high pressure fuel pump in which a low pressure pipe as the suction side pipe is connected to the pulsation absorbing chamber. In what was described in any one of Claims 1-5,
A plunger type high-pressure fuel pump in which the actuator is provided in a pump housing part opposite to a side where the plunger is located across the pressurizing chamber. In what was described in any one of Claims 1-6,
A plunger-type high-pressure fuel pump, wherein the actuator is attached to a side surface of the pump housing in a direction crossing the plunger. In what is described in any one of Claims 2-7,
A plunger type high pressure fuel pump in which the seal member is attached to the pump housing. A pressurizing chamber provided in the pump housing;
A plunger that reciprocates according to a rotating cam;
A suction valve that opens and closes between the pressurizing chamber and the suction side pipe;
A discharge valve for opening and closing between the pressurizing chamber and the discharge side pipe line;
An actuator for controlling opening and closing of the suction valve;
A pulsation absorbing chamber provided in a fuel intake passage formed in the pump housing between the intake valve and the intake side pipe;
An accumulator provided in the pulsation absorption chamber,
A plunger type high-pressure fuel pump, wherein the pressurizing chamber is connected to the suction side pipe line via the pulsation absorption chamber, and the suction side pipe as a low pressure pipe is connected to the pulsation absorption chamber.

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