JP6233181B2 - Fuel supply device for internal combustion engine - Google Patents

Description

  The present invention is an internal combustion engine that includes a fuel pump that pumps fuel to be supplied to a fuel injection valve of an internal combustion engine from a fuel tank and discharges the fuel to the fuel injection valve side, and a check valve provided downstream of the fuel pump. The present invention relates to an engine fuel supply device.

  For example, in Patent Document 1 below, a check valve is provided on the downstream side of a fuel pump that pumps up fuel in a fuel tank and supplies it to a fuel injection valve, and a fuel pressure in a downstream fuel passage is provided downstream of the check valve. A fuel supply device is described that includes a relief valve that returns fuel to the fuel tank when the fuel cell becomes excessively high. Here, the check valve is for preventing the back flow of fuel from the fuel injection valve side to the fuel pump side.

JP 2013-245635 A

  In the case of the above fuel supply device, when pressure pulsation occurs in the fuel supply passage downstream of the check valve, the check valve is closed because the pressure on the downstream side of the check valve becomes higher than the pressure on the upstream side. The inventors have found that the supply accuracy of the fuel supplied from the fuel pump to the fuel injection valve may be lowered.

  The present invention has been made in view of such circumstances, and an object thereof is to pump a fuel from a fuel tank and discharge it to the fuel injection valve side, and a check valve provided on the downstream side of the fuel pump. It is an object of the present invention to provide a fuel supply device for an internal combustion engine that can suitably suppress closing of a check valve due to pressure pulsation.

Hereinafter, means for solving the above-described problems and the effects thereof will be described. The invention according to claim 1 of the present invention is based on the following technical idea 1: “Opening when the fuel pressure upstream of the check valve and downstream of the fuel pump is equal to or higher than a predetermined pressure. The fuel pump is “operated based on the target value variably set as the target value of the fuel pressure downstream of the check valve”. And the sum of the value obtained by multiplying the area of the downstream pressure receiving surface by the minimum value of the target value and the force exerted by the valve closing assisting member on the check valve is that of the upstream pressure receiving surface. This corresponds to a correction of a point that is larger than the value obtained by multiplying the area by the predetermined pressure.
Technical idea 1: A fuel pump that pumps fuel to be supplied to a fuel injection valve of an internal combustion engine from a fuel tank and discharges the fuel to the fuel injection valve side, and a check valve provided on the downstream side of the fuel pump. The check valve communicates between the upstream side that is the fuel pump side and the downstream side that is the fuel injection valve side, a valve body that opens and closes the communication path, and a direction that blocks the communication path And a valve closing assisting member that exerts a displacement force on the valve body, and closes when the fuel pump is stopped. The valve body is a pressure receiving surface located on the upstream side of the check valve. A force in the valve opening direction is exerted by the pressure applied to the upstream pressure receiving surface, and a force in the valve closing direction is exerted by the pressure applied to the downstream pressure receiving surface, which is a pressure receiving surface located on the downstream side of the check valve. Above the area of the side pressure-receiving surface The fuel supply system for an internal combustion engine towards the area of the side pressure-receiving surface is set to a small value.

  In the above device, when the fuel is discharged from the fuel pump and the check valve is open, the valve body has a force in the direction for closing the check valve as a force by the valve closing auxiliary member and the downstream side. While the force applied by the fuel is exerted on the pressure receiving surface, the force applied by the fuel is exerted on the upstream pressure receiving surface as the force in the direction of opening the check valve. Here, in the above device, since the area of the downstream pressure receiving surface is smaller than the area of the upstream pressure receiving surface, the fuel on the upstream pressure receiving surface is greater than the force by the valve closing assisting member and the force applied by the fuel to the downstream pressure receiving surface. The force applied by can be increased. In this case, even if a force due to pressure pulsation is applied to the downstream pressure receiving surface, it is possible to suitably suppress the occurrence of a situation where the check valve closes.

The system block diagram concerning one Embodiment. Sectional drawing which shows the cross-sectional structure at the time of valve closing of the non-return valve concerning the embodiment. Sectional drawing which shows the cross-sectional structure at the time of valve opening of the non-return valve concerning the embodiment.

Hereinafter, an embodiment of a fuel supply device for an internal combustion engine will be described with reference to the drawings.
As shown in FIG. 1, the fuel tank 10 is filled with gasoline fuel. Connected to the fuel tank 10 is a low-pressure fuel passage 12 which is a passage for supplying fuel filled in the fuel tank 10 to the internal combustion engine. A low-pressure delivery pipe 14 is connected to the low-pressure fuel passage 12, and the low-pressure delivery pipe 14 is provided with a port fuel injection valve 15 that injects fuel into the intake port of each cylinder.

  A branch passage 13 is connected to the low pressure fuel passage 12. The branch passage 13 is provided with a high-pressure fuel pump 16 that sucks, pressurizes, and discharges fuel flowing into the branch passage 13. The high-pressure fuel pump 16 is an engine-driven pump. Specifically, the high-pressure fuel pump 16 includes a plunger 20 that repeats reciprocation in the cylinder 19 in accordance with the rotation of the camshaft 18. A pressurizing chamber 21 that is a space defined by the cylinder 19 and the plunger 20 is connected to the branch passage 13 via an electromagnetic valve 22. Then, when the volume of the pressurizing chamber 21 is enlarged in a state where the electromagnetic valve 22 is opened, the fuel in the branch passage 13 is sucked into the pressurizing chamber 21. When the volume in the pressurizing chamber 21 is reduced, the fuel in the pressurizing chamber 21 is pressurized and discharged to the high-pressure fuel passage 24 by closing the electromagnetic valve 22. Here, the fuel discharge amount is adjusted by the closing timing of the electromagnetic valve 22. That is, as the closing timing of the electromagnetic valve 22 is delayed, the amount of fuel returned from the pressurizing chamber 21 to the branch passage 13 increases and the discharge amount decreases.

  The high pressure fuel passage 24 is connected to a high pressure side delivery pipe 26. The high-pressure delivery pipe 26 is provided with an in-cylinder fuel injection valve 27 that directly injects fuel into the combustion chamber of each cylinder.

  The fuel tank 10 is provided with an electronically controlled feed pump 30 that pumps up and discharges fuel in the fuel tank 10. Specifically, the feed pump 30 pumps up the fuel in the suction container 31 in the fuel tank 10. A check valve 32 is provided at the fuel discharge port of the feed pump 30, and the downstream of the check valve 32 is connected to a discharge passage 34 via a filter 33. The discharge passage 34 is connected to the low pressure fuel passage 12 via a check valve 36. Here, the check valve 36 is for restricting the inflow of fuel from the downstream side (low pressure fuel passage 12 side) to the upstream side (discharge passage 34 side).

  A relief valve 38 is connected to the low pressure fuel passage 12. The relief valve 38 is opened when the pressure of the low-pressure fuel passage 12 becomes equal to or higher than a specified pressure, and allows the low-pressure fuel passage 12 to communicate with the fuel tank 10.

  A branch passage 40 is provided in the discharge passage 34, and the branch passage 40 is connected to a residual pressure holding valve 42. The residual pressure holding valve 42 is opened when the pressure exceeds a predetermined pressure lower than the specified pressure. In the present embodiment, the predetermined pressure is set so that the residual pressure holding valve 42 is opened particularly when the feed pump 30 is discharging the fuel to supply the fuel to the internal combustion engine. .

  A return passage 44 for returning the fuel pumped up by the feed pump 30 to the suction container 31 is connected downstream of the residual pressure holding valve 42. Jet pumps 46 and 48 are connected to the return passage 44. For this reason, during the period in which the feed pump 30 discharges fuel to supply fuel to the internal combustion engine, the residual pressure holding valve 42 is opened, and the fuel that has flowed into the branch passage 40 passes through the return passage 44 to the intake container. Return to 31. Thus, when the remaining amount of fuel in the fuel tank 10 is small, a negative pressure is generated in the vicinity of the jet pump 46, so that the fuel in the vicinity of the jet pump 46 is sucked and sucked into the suction container 31 side. On the other hand, a communication passage 50 is connected in the vicinity of the jet pump 48. Therefore, when the remaining amount of fuel in the fuel tank 10 is small, a negative pressure is generated in the vicinity of the jet pump 48 when the fuel is returned to the suction container 31 via the return passage 44. The communication passage 50 is connected to a filter 52 disposed at a position away from the feed pump 30 in the fuel tank 10. For this reason, when a negative pressure is generated in the vicinity of the jet pump 48, the fuel at a position separated from the feed pump 30 is sucked into the communication passage 50 through the filter 52 and eventually merges with the fuel flowing in the return passage 44. It flows into the container 31 for inhalation.

As described above, the residual pressure holding valve 42, the return passage 44, and the jet pumps 46 and 48 have a function of collecting the fuel in the fuel tank 10 in the suction container 31.
The ECU 54 is an electronic control device that electronically operates the electromagnetic valve 22, the port fuel injection valve 15, the in-cylinder fuel injection valve 27, and the feed pump 30. Here, the ECU 54 variably controls the discharge amount by operating the rotational speed of the feed pump 30. In particular, the ECU 54 variably controls the discharge amount of the feed pump 30 according to the fuel consumed by the port fuel injection valve 15 and the in-cylinder fuel injection valve 27. Specifically, control is performed to bring the discharge amount of the feed pump 30 close to the amount of fuel consumed by the port fuel injection valve 15 and the in-cylinder fuel injection valve 27 and the amount of fuel returned to the vicinity of the fuel tank 10 via the residual pressure holding valve 42. I do. At this time, the ECU 54 controls the fuel pressure in the low pressure side delivery pipe 14 to a target value and variably sets the target value.

  This is to operate the feed pump 30 by the operation amount for controlling the fuel pressure in the low pressure side delivery pipe 14 to the target value and the operation amount for controlling the fuel pressure in the high pressure side delivery pipe 26 to the target value. Can be done. Here, the operation amount for controlling the fuel pressure in the low pressure side delivery pipe 14 to the target value may be calculated from the open loop operation amount and the feedback operation amount. Here, the feedback operation amount is an operation amount for feedback-controlling the detection value of the low-pressure side fuel pressure sensor 56 that detects the fuel pressure in the low-pressure side delivery pipe 14 to the target value. Further, the operation amount for controlling the fuel pressure in the high-pressure delivery pipe 26 to the target value may be calculated from the open loop operation amount and the feedback operation amount. Here, the feedback operation amount is an operation amount for feedback-controlling the detection value of the high-pressure side fuel pressure sensor 58 that detects the fuel pressure in the high-pressure side delivery pipe 26 to the target value.

  The fuel pressure in the low-pressure fuel passage 12 becomes a target value of the fuel pressure in the low-pressure delivery pipe 14 except for pressure pulsation. For this reason, in order to maintain high controllability of the fuel pressure in the low-pressure delivery pipe 14, the specified pressure at which the relief valve 38 opens is set higher than the target value of the fuel pressure in the low-pressure delivery pipe 14. There is a need.

  Further, in order to open the residual pressure holding valve 42 when fuel is being supplied by the feed pump 30, the predetermined pressure for opening the residual pressure holding valve 42 is set to the low pressure side delivery pipe 14. The fuel pressure must be lower than the target value.

  Here, in the present embodiment, the specified pressure is set to “500 kPa or more”, desirably “500 to 700 kPa”, more desirably “550 to 700 kPa”, and the predetermined pressure is “500 kPa or more”, desirably “500”. ˜700 kPa ”, more desirably“ 550 kPa to 700 kPa ”.

  The check valve 36 is provided in association with variably setting the target value of the fuel pressure in the low pressure side delivery pipe 14. That is, in the case of the above configuration, when the feed pump 30 is stopped, the residual pressure holding valve 42 is also closed. Here, when the check valve 36 is not provided, the fuel pressure in the low pressure fuel passage 12 is reduced to about the predetermined pressure that opens the residual pressure holding valve 42. In this case, as described above, the predetermined pressure cannot be increased due to variably setting the target value of the fuel pressure in the low-pressure delivery pipe 14, so the vapor pressure of the fuel decreases. For this reason, we are anxious about vapor generating during dead soak. On the other hand, since the check valve 36 is provided, the fuel pressure in the low pressure fuel passage 12 can be maintained at a value higher than the predetermined pressure, so that the generation of vapor can be suppressed.

  By the way, when the high-pressure fuel pump 16 is provided, the high-pressure fuel pump 16 sucks fuel from the branch passage 13 or discharges the sucked fuel to the branch passage 13, thereby causing pressure pulsation in the low-pressure fuel passage 12. . In particular, during the period in which the in-cylinder fuel injection valve 27 does not inject fuel, almost all of the fuel once sucked into the pressurizing chamber 21 is expelled into the branch passage 13 so that pressure pulsation becomes significant.

  Here, when pressure pulsation occurs in the high-pressure fuel pump 16, the check valve 36 closes due to the pressure on the downstream side of the check valve 36 becoming higher than the pressure on the upstream side. Controllability may be reduced. That is, when the check valve 36 is closed, the relationship between the rotation speed of the feed pump 30 and the discharge amount is lost, so that depending on the rotation speed of the feed pump 30 set by the ECU 54 to control the discharge amount of the feed pump 30. The target discharge amount will not be achieved.

  The phenomenon in which the check valve 36 closes is particularly caused by the fact that the specified pressure for opening the relief valve 38 needs to be higher than the target value of the fuel pressure in the low-pressure delivery pipe 14 variably set. It tends to occur. This is because it is difficult to release the pressure pulsation energy to the fuel tank 10 side by opening the relief valve 38. When the check valve 36 is closed, the check valve 36 becomes a fixed end of the pressure pulsation, so that a resonance phenomenon occurs, which may cause a problem of sound and vibration due to the pulsation. That is, resonance occurs when the phase of the pressure pulsation caused by the intake and discharge of fuel from the high-pressure fuel pump 16 and the reflected wave of the pressure pulsation at the check valve 36 coincide. When resonance occurs, the pressure pulsation at that time may cause a problem of sound and vibration.

Therefore, in this embodiment, the structure of the check valve 36 is set as follows.
FIG. 2 shows a cross-sectional structure of the check valve 36 according to the present embodiment. In particular, FIG. 2 is a cross-sectional view of the check valve 36 in a closed state.

  As illustrated, the check valve 36 includes a communication passage 60 connected to the discharge passage 34 and the low-pressure fuel passage 12. The check valve 36 includes a valve body 62 and a valve seat 64, and closes when the valve body 62 is seated on the valve seat 64. The check valve 36 includes a coil spring 66 having ends fixed to the valve body 62 and the fixed portion 68. The coil spring 66 presses the valve body 62 against the valve seat 64 by elastic force.

  According to such a configuration, when the fuel is not discharged from the feed pump 30, the pressure on the discharge passage 34 side decreases, so that the valve body 62 is added to the upstream pressure receiving surface 62 a that is the upstream pressure receiving surface. The force is smaller than the force exerted by the fuel and the coil spring 66 on the downstream pressure receiving surface 62b, which is the downstream pressure receiving surface of the valve body 62. Accordingly, the valve body 62 is seated on the valve seat 64, and the discharge passage 34 side that is the upstream side of the communication passage 60 is blocked by the valve body 62.

FIG. 3 shows a cross-sectional view when the check valve 36 is opened.
As illustrated, when the valve body 62 is separated from the valve seat 64, the discharge passage 34 and the communication passage 60 communicate with each other, and the check valve 36 is opened.

Here, in order to maintain the check valve 36 in the open state, the following expression (c1) is established using the area S1 of the downstream pressure receiving surface 62b and the area S2 of the upstream pressure receiving surface 62a. Is required. The control fuel pressure is a target value of the fuel pressure in the low pressure side delivery pipe 14.
S1 × (control fuel pressure + pulsation) + (elastic force of coil spring 66) <S2 × (control fuel pressure)
... (c1)
Here, in the present embodiment, due to the structure, there is a relationship of “S2> S1” between the area S2 of the upstream pressure receiving surface 62a and the area S1 of the downstream pressure receiving surface 62b. For this reason, it becomes easy to satisfy the conditions defined by the above formula. Incidentally, in the present embodiment, the check valve 36 is closed when the feed pump 30 is stopped, and in order to prevent the fuel from flowing from the low pressure fuel passage 12 to the discharge passage 34, the following equation (c2) is further reduced. Make it happen.
S1 × (minimum value of control fuel pressure) + (elastic force of coil spring 66)> S2 × (predetermined pressure) (c2)
Next, the operation of this embodiment will be described.

  When fuel is supplied from the feed pump 30 to the internal combustion engine and the internal combustion engine is driven, the plunger 20 of the high-pressure fuel pump 16 reciprocates in the cylinder 19. Here, when fuel is sucked into the pressurizing chamber 21 from the branch passage 13 and then returned to the branch passage 13, pressure pulsation occurs in the low-pressure fuel passage 12. However, since the force due to the pulsation and the force due to the control fuel pressure are intended to close the valve body 62, the area S1 of the downstream pressure receiving surface 62b is smaller than the area S2 of the upstream pressure receiving surface 62a, so the upstream side Compared to the force exerted on the pressure receiving surface 62a, it is difficult to increase. For this reason, the check valve 36 can be maintained in an open state, and as a result, the controllability of fuel supply can be maintained high.

According to this embodiment described above, the following effects can be obtained.
(1) By making the area S2 of the upstream pressure receiving surface 62a larger than the area S1 of the downstream pressure receiving surface 62b, the check valve 36 is maintained in the open state even when pressure pulsation occurs. Can do.

  (2) The area S2 of the upstream pressure receiving surface 62a and the area S1 of the downstream pressure receiving surface 62b are set so as to satisfy the above formula (c2). Thereby, the check valve 36 can be closed when the feed pump 30 is stopped, and as a result, generation of vapor from the low-pressure fuel passage 12 can be suppressed.

<Correspondence between technical idea and embodiment>
Hereinafter, a representative correspondence relationship between the technical idea described in the above “Means for Solving the Problems” and the embodiment will be described.

Fuel pump 30, check valve 36, valve closing assist member 66
<Other embodiments>
The above embodiment may be modified as follows.

  The elastic body that fixes the valve body 62 in the closed position when the feed pump 30 does not discharge fuel is not limited to the coil spring 66 but may be a leaf spring, rubber, or the like. Further, the elastic body is not limited to the one connected to the downstream pressure receiving surface 62 b of the valve body 62. For example, it may be connected to the upstream pressure receiving surface 62a side. In this case, for example, instead of the cylindrical valve seat 64, a part of the cylindrical shape may be deleted and an elastic body may be disposed in the deleted space. The valve closing assisting member that exerts a force in the valve closing direction on the valve body 62 is not limited to an elastic body, and may be a permanent magnet, for example. In this case, for example, the valve closing auxiliary member can be configured by configuring the valve body 62 and the valve seat 64 with permanent magnets.

  The communication path 60 is not limited to one and may be a plurality. Further, for example, the communication passage 60 may be an annular member having the displacement direction of the valve body 62 as an axis. In this case, the communication passage 60 covers the periphery of the region where the valve body 62 and the coil spring 66 are disposed.

It is not essential to provide the relief valve 38 downstream of the check valve 36. For example, a branch passage may be connected to the communication passage 60 and the relief valve 38 may be connected thereto.
The high-pressure fuel pump 16 is not limited to the one provided with an electronically controlled valve body that adjusts the fuel discharge amount, and may be provided with an electronically controlled valve body that adjusts the intake amount. Even in this case, if pressure pulsation occurs due to the intake of fuel from the high-pressure fuel pump 16, this may cause the check valve 36 to close. The setting is valid.

  In the above embodiment, the high pressure fuel pump 16 and the in-cylinder fuel injection valve 27 are provided, but the present invention is not limited thereto. When there is a possibility that the check valve 36 may be closed due to pressure pulsation caused by some factor such as pressure pulsation accompanying fuel injection of the port fuel injection valve 15, the check valve is set in the above-described embodiment or its modification. It is valid.

  It is not essential to provide the residual pressure holding valve 42. Even if this is not provided, as described in Patent Document 1, if a check valve is provided on the downstream side of the feed pump 30, if this is closed by pressure pulsation, the amount of fuel supplied Since controllability is reduced, the setting of the check valve in the above embodiment or its modification is effective.

  ・ The fuel is not limited to gasoline. Even if fuel other than gasoline is provided with a check valve on the downstream side of the feed pump 30, if this valve is closed by pressure pulsation, the controllability of the fuel supply amount is reduced, so the above-described embodiment and its modifications The check valve setting in the example is effective.

  DESCRIPTION OF SYMBOLS 10 ... Fuel tank, 12 ... Low pressure fuel passage, 13 ... Branch passage, 14 ... Low pressure side delivery pipe, 15 ... Port fuel injection valve, 16 ... High pressure fuel pump, 18 ... Cam shaft, 19 ... Cylinder, 20 ... Plunger, 21 DESCRIPTION OF SYMBOLS ... Pressure chamber, 22 ... Solenoid valve, 24 ... High pressure passage, 26 ... High pressure side delivery pipe, 27 ... In-cylinder fuel injection valve, 30 ... Feed pump, 31 ... Container for suction, 32 ... Check valve, 33 ... Filter 34 ... Discharge passage, 36 ... Check valve, 38 ... Relief valve, 40 ... Branch passage, 42 ... Residual pressure holding valve, 44 ... Return passage, 46, 48 ... Jet pump, 50 ... Communication passage, 52 ... Filter, 54 ... ECU, 56 ... Low pressure side fuel pressure sensor, 58 ... High pressure side fuel pressure sensor, 60 ... Communication passage, 62 ... Valve body, 62a ... Upstream pressure receiving surface, 62b ... Downstream pressure receiving surface, 64 ... Valve seat, 66 Coil spring, 68 ... fixed portion.

Claims (1)

A fuel pump that pumps fuel to be supplied to a fuel injection valve of an internal combustion engine from a fuel tank and discharges the fuel to the fuel injection valve side;
A check valve provided downstream of the fuel pump ;
A residual pressure holding valve upstream of the check valve and downstream of the fuel pump that opens at a predetermined pressure or higher and returns the fuel to the fuel tank ;
The fuel pump is operated based on the target value variably set as a target value of the fuel pressure downstream of the check valve,
The check valve is
A communication passage for communicating between the upstream side which is the fuel pump side and the downstream side which is the fuel injection valve side;
A valve body for opening and closing the communication passage;
A valve closing assisting member that exerts a force on the valve body to displace the communication passage in a direction to block the communication passage ;
The valve body is a pressure receiving surface located on the downstream side of the check valve by being subjected to a force in the valve opening direction by pressure applied to the upstream pressure receiving surface which is a pressure receiving surface located on the upstream side of the check valve. A force in the valve closing direction is exerted by the pressure applied to the downstream pressure receiving surface, and the area of the downstream pressure receiving surface is set to a smaller value than the area of the upstream pressure receiving surface ,
The sum of a value obtained by multiplying the area of the downstream pressure receiving surface by the minimum value of the target value and the force exerted by the valve closing assisting member on the check valve is the predetermined pressure on the area of the upstream pressure receiving surface. A fuel supply device for an internal combustion engine that is larger than a value obtained by multiplying .