JP4640387B2 - High pressure pump and fuel supply device for internal combustion engine - Google Patents

Description

  The present invention relates to a high-pressure pump and a fuel supply device for an internal combustion engine, and more particularly to a high-pressure pump that further pressurizes and pressurizes already pressurized fuel and a fuel supply device for the internal combustion engine.

  Among internal combustion engines mounted on vehicles such as passenger cars and trucks, there is a direct injection type internal combustion engine that supplies fuel directly into the combustion chamber of each cylinder of the internal combustion engine. In such a fuel supply device for an internal combustion engine, the fuel in the fuel tank is pumped up by an electric low-pressure fuel pump and pressurized to a predetermined feed pressure, and the fuel is further pressurized by a high-pressure fuel pump, via a delivery pipe. Some are pumped to the fuel injection valve.

  In such a fuel supply device, when the pressure of the high-pressure fuel in the delivery pipe becomes a predetermined pressure, for example, about a dozen MPa or more due to an increase in the fuel pressure at the time of abnormality or when the engine is stopped, excess fuel in the delivery pipe is fueled. In order to return to the tank, there is a delivery pipe provided with a relief valve (for example, see Patent Document 1).

JP 2006-207451 A

  However, in the configuration in which the relief valve is provided in the delivery pipe, a drain pipe is required to return the relief fuel to the fuel tank, so that the cost is high and there is also a problem from occurrence of evacuation.

  Therefore, it is desirable to provide a relief valve in the high-pressure fuel pump and eliminate the relief piping. The valve opening pressure of the relief valve is the maximum of the injector in order to keep the fuel pressure at the valve opening pressure of the relief valve and enable direct fuel injection with the injector even when the fuel pressure control becomes impossible at the time of abnormality. It is desirable to set it below the operating fuel pressure.

  FIG. 5 is a diagram for explaining the fuel pressure of each part of a conventional fuel supply apparatus. The figure shows an example of (1) the fuel pressure at the outlet of the discharge valve, (2) the fuel pressure detected by the fuel pressure sensor, and (3) the fuel pressure at the inlet of the relief valve when the fuel is discharged at high speed. The horizontal axis represents the crank angle CA, and the vertical axis represents the fuel pressure (MPa).

  Here, instead of disposing a relief valve in the delivery pipe, if the relief valve is built in the high-pressure pump and the relief valve is disposed immediately after the discharge valve, the relief valve is Since the valve is opened each time by the surge pressure (pulsation fuel pressure) of the pressure supply, it becomes a system with low reliability against the wear of the relief valve and foreign matter.

  On the other hand, in the configuration in which the valve opening pressure of the relief valve is increased to the surge pressure, it is necessary to increase the maximum operating fuel pressure of the injector, and there is a problem that the injector needs to be enlarged and the cost is increased.

  The present invention has been made in view of the above, and an object of the present invention is to provide a high-pressure pump and an internal combustion engine fuel supply device capable of relieving fuel from a fuel injection means with a low-cost configuration.

  In addition, the present invention has been made in view of the above, and a high-pressure pump and an internal combustion engine capable of preventing a relief valve from being opened by a surge pressure (pulsation fuel pressure) generated by driving a high-pressure pump during pumping An object of the present invention is to provide an engine fuel supply device.

  In order to solve the above-described problems and achieve the object of the present invention, the present invention pressurizes fuel supplied through a low-pressure passage in a pressurizing chamber by reciprocation of a plunger, and passes through the high-pressure passage. A high pressure pump that pumps the fuel to the fuel injection means, a discharge valve for maintaining a constant fuel pressure of the fuel supplied to the fuel injection means, a relief valve connected to the inside of the discharge valve via a passage, and the relief A pilot valve that is connected between the downstream side of the valve and the low-pressure passage and whose valve opening pressure is set to be equal to or lower than the maximum operating fuel pressure of the fuel injection means.

  According to a preferred aspect of the present invention, the discharge valve and the back pressure chamber of the relief valve are connected by an orifice, and the valve opening pressure of the relief valve is changed to the valve opening pressure-surge pressure of the pilot valve. It is desirable to set.

  In order to solve the above problems and achieve the object of the present invention, the present invention provides a low-pressure pump capable of pressurizing and feeding fuel to a predetermined feed pressure, and fuel supplied from the low-pressure pump to a plunger. A high-pressure pump that pressurizes and pumps in a pressurizing chamber by reciprocation; fuel injection means capable of injecting fuel pressurized by the high-pressure pump into a combustion chamber of an internal combustion engine; and the low-pressure pump and the high-pressure pump. A low-pressure passage for connection, and a high-pressure passage for connecting the high-pressure pump and the fuel injection means, wherein the high-pressure pump is a discharge valve for keeping the fuel pressure of the fuel supplied to the fuel injection means constant. A relief valve connected to the inside of the discharge valve via a passage, and a pilot connected to a downstream side of the relief valve and a low pressure passage, the valve opening pressure of which is set below the maximum operating fuel pressure of the fuel injection means With a valve And said that there was example.

  According to a preferred aspect of the present invention, the discharge valve and the back pressure chamber of the relief valve are connected by an orifice, and the valve opening pressure of the relief valve is changed to the valve opening pressure-surge pressure of the pilot valve. It is desirable to set.

  According to the high pressure pump of the present invention, in the high pressure pump that pressurizes the fuel supplied through the low pressure passage in the pressurizing chamber by the reciprocation of the plunger and pumps the fuel to the fuel injection means through the high pressure passage. A discharge valve for keeping the fuel pressure of the fuel supplied to the fuel injection means constant, a relief valve connected to the inside of the discharge valve via a passage, and connected between a downstream side of the relief valve and the low pressure passage. And a pilot valve whose valve opening pressure is set to be equal to or lower than the maximum operating fuel pressure of the fuel injection means, a high-pressure pump capable of relieving fuel from the fuel injection means with a low-cost configuration There is an effect that it can be provided.

  According to the high pressure pump of the present invention, the inside of the discharge valve and the back pressure chamber of the relief valve are connected by an orifice, and the opening pressure of the relief valve is set to the opening pressure-surge pressure of the pilot valve. Therefore, it is possible to provide a high-pressure pump that can prevent the relief valve from opening due to surge pressure (pulsation fuel pressure) generated by driving the high-pressure pump during pumping. Play.

  Embodiments of a fuel supply device for an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  In the present embodiment, a case will be described in which the present invention is applied to a high-pressure pump used in an in-cylinder injection (for example, 6-cylinder) gasoline engine mounted on an automobile and a fuel supply device for an internal combustion engine. FIG. 1 is a schematic configuration diagram of a fuel supply device for an internal combustion engine according to an embodiment of the present invention, and FIG. 2 is a diagram illustrating a schematic configuration of a discharge valve, a relief valve, and a pilot valve of the high-pressure fuel pump of FIG. .

  As shown in FIG. 1, the fuel supply device 1 of the present embodiment is pressurized by a fuel tank 10, a low-pressure feed pump 11 as a low-pressure pump that pressurizes fuel in the fuel tank 10, and the low-pressure feed pump 11. A high pressure fuel pump 20 as a high pressure pump for further pressurizing the fuel, a fuel injection mechanism 40 as a fuel injection means for injecting the pressurized fuel, and an ECU 70.

  The fuel tank 10 stores fuel supplied to the engine, and a low-pressure feed pump 11 is attached to the fuel tank 10.

  The low-pressure feed pump 11 can pressurize the fuel in the fuel tank 10 to a predetermined feed pressure (for example, about several hundred kPa) by an electric motor, and can pump the fuel as low-pressure fuel. The low-pressure feed pump 11 is connected to the suction port 21 of the high-pressure fuel pump 20 via a low-pressure fuel supply pipe 50 serving as a low-pressure passage. Further, the low pressure fuel supply pipe 50 is provided with a branching low pressure fuel return pipe 50a.

  The low pressure fuel return pipe 50 a has a proximal end branched from the low pressure fuel supply pipe 50 in the fuel tank 10, and a distal end is also located in the fuel tank 10. A low pressure adjusting valve 12 is provided on the low pressure fuel return pipe 50a. The low-pressure adjusting valve 12 is opened when the pressure of the fuel in the low-pressure fuel supply pipe 50 (hereinafter referred to as “fuel pressure”) becomes higher than the feed pressure, whereby the fuel discharged from the low-pressure feed pump 11 is discharged. Is returned to the fuel tank 10 through the low-pressure fuel return pipe 50a, and the fuel pressure in the low-pressure fuel supply pipe 50 can be kept constant. The low pressure fuel supply pipe 50 is branched to 50 b and connected to the downstream side of the pilot valve 33 of the high pressure fuel pump 20.

  The high-pressure fuel pump 20 can be driven by the rotation of the crankshaft of the engine. The high-pressure fuel pump 20 pressurizes the low-pressure fuel that has already been pressurized by the low-pressure feed pump 11 to a high pressure (for example, about several tens of kPa). This is a metering type high-pressure pump for supplying fuel to the fuel injection mechanism 40 as fuel. Further, the high-pressure fuel pump 20 has a discharge valve 31 connected to a delivery pipe 42 of a fuel injection mechanism 40 described later via a high-pressure fuel supply pipe 60 serving as a high-pressure passage.

  The high-pressure fuel pump 20 includes a casing 23, a plunger 24, a pressurizing chamber 25, a spill valve 26 as a metering valve, a spring 27 as an urging means, a solenoid 28, a discharge valve 31, and a relief valve. 32 and a pilot valve 33.

  The casing 23 is formed in a cylindrical shape, and a suction port 21 for sucking low-pressure fuel is formed at one end portion thereof, and a discharge port 22 for discharging high-pressure fuel is formed on a side surface portion. The plunger 24 is supported in the casing 23 so as to be able to reciprocate. The pressurizing chamber 25 is a space for pressurizing the fuel, and is defined by one end surface of the plunger 24 and the inner surface of the casing 23. The discharge port 22 is formed so as to communicate with the pressurizing chamber 25. The spill valve 26 is provided at the suction port 21 of the casing 23, can move in the axial direction of the casing 23, and can open and close the suction port 21, thereby communicating the suction port 21 and the pressurizing chamber 25. be able to.

  The spill valve 26 is biased by a spring 27 in a direction in which the suction port 21 can be opened, and can be opened and closed by applying a suction force in a direction in which the suction port 21 can be closed by a solenoid 28. Composed. The solenoid 28 is electrically connected to the ECU 70, and energization of the solenoid 28 is controlled by a control signal transmitted from the ECU 70.

  The spill valve 26 is a so-called normally open spill valve. That is, when the solenoid 28 is not energized, the spill valve 26 is separated from the suction port 25 by the spring 27 (on the pressurizing chamber 25 side). The intake port 21 is opened (valve open state), and fuel can flow through the intake port 21.

  On the other hand, when the solenoid 28 is energized, the spill valve 26 is sucked by the solenoid 28 in a direction approaching the suction port 21 (direction of the solenoid 28), and the suction port 21 is closed (closed state). Inhalation and outflow of fuel through the port 21 are blocked. As a result, even if the solenoid 28 is disconnected, the suction port 21 is maintained in an open state, so that full-pressure feeding is not continued and damage to the fuel supply system is minimized. be able to.

  The plunger 24 is formed in a cylindrical shape whose outer diameter is slightly smaller than the inner diameter of the casing 23, and is provided so as to be able to reciprocate with respect to the casing 23. Further, the plunger 24 forms a pressurizing chamber 25 on one end surface side and is urged so as to be pressed against a cam 29 provided on the other end surface side by a spring (not shown). The cam 29 is fixed to a camshaft 30, and the camshaft 30 rotates in conjunction with the rotation of a crankshaft of an engine (not shown) via a mechanism (not shown). The cam 29 rotates together with the cam shaft 30, whereby the plunger 24 is pressed by the cam 29 and reciprocates with respect to the casing 23.

  The pressurizing chamber 25 is capable of sucking fuel from the suction port 21 by changing its volume in accordance with the reciprocating motion of the plunger 24, and further pressurizing the sucked fuel and can be pumped from the discharge port 22. Here, the reciprocating movement of the plunger 24 includes a suction stroke in which the plunger 24 moves in the direction of increasing the volume of the pressurizing chamber 25 and a pressure-feeding stroke in which the plunger 24 moves in a direction of decreasing the volume. In the intake stroke, the volume of the pressurizing chamber 25 increases as the plunger 24 moves to the cam 29 side. At this time, the ECU 70 controls the solenoid 28 to a non-energized state and opens the intake port 21. The internal fuel pressure decreases, the suction input for sucking fuel acts in the pressurizing chamber, and the low pressure fuel in the low pressure fuel supply pipe 50 can be sucked into the pressurizing chamber 25 through the suction port 21.

  On the other hand, in the pressure feeding stroke, the volume of the pressurizing chamber 25 is reduced by the plunger 24 moving to the spill valve 26 side. At this time, the ECU 70 controls the solenoid 28 to be in an energized state and closes the suction port 21. The internal fuel pressure rises, the pressing force for pressing the fuel acts in the pressurizing chamber, and the high pressure fuel pressurized to a predetermined pressure is discharged from the discharge port 22 through the high pressure fuel supply pipe 60 to the fuel injection mechanism 40. Can be pumped. Further, by adjusting the energization timing of the solenoid 28, that is, the closing timing of the suction port 21, the amount of fuel sucked can be adjusted.

  The discharge valve 31 is mounted between the discharge port 22 and the high-pressure fuel supply pipe 60 and is used to keep the fuel pressure of the fuel supplied to the delivery pipe 42 constant. As shown in FIGS. 1 and 2, the discharge valve 31 includes a valve body 31a that can close the opening, and a spring 31b that urges the valve body 31a in the valve closing direction. When the pressure of the low-pressure fuel in the pressurizing chamber 25 of the high-pressure fuel pump 20 becomes equal to or higher than a predetermined pressure (for example, about several tens of KPa), the discharge valve 31 opens the valve body 31a and the fuel is supplied to the high-pressure fuel supply pipe 60. Can pass through.

  Further, the inside of the discharge valve 31 is connected to the inlet of the relief valve 32 by a passage 31d, and is connected to the back pressure chamber 32 of the relief valve 32 by an orifice 31e. The sectional area of the orifice 31e is set smaller than the sectional area of the passage 31d.

  The relief valve 32 forms a relief passage in cooperation with the pilot valve 33. As shown in FIGS. 1 and 2, the relief valve 32 includes a valve body 32a that can close the opening, a spring 32b that urges the valve body 32a in the valve closing direction, an inside of the discharge valve 31, and an orifice. The back pressure chamber 32c connected by 31e is provided. A pilot valve 33 is connected to the downstream side of the relief valve 32. The valve opening pressure of the relief valve 32 is set to a predetermined pressure P3 = the valve opening pressure P2 of the pilot valve 33—the surge pressure P1.

  The pilot valve 33 is mounted between the downstream side of the relief valve 32 and the low pressure fuel supply pipe 50b. As shown in FIGS. 1 and 2, the pilot valve 33 includes a valve body 33 a that can close the opening and a spring 33 b that biases the valve body 33 a in the valve closing direction. The valve opening pressure of the pilot valve 33 is set to a predetermined pressure P2 (for example, about ten and several MPa) that is equal to or lower than the maximum operating fuel pressure of the injector 41.

  The fuel injection mechanism 40 includes the above-described delivery pipe 42 and the above-described plurality of injectors 41 connected to the delivery pipe 42. More specifically, one injector 41 is provided for each of the combustion chambers provided corresponding to the cylinders of the engine (six in the example shown in the figure). The delivery pipe 42 includes a first delivery pipe 42a and a second delivery pipe 42b, and three injectors 41 are connected to each of the first delivery pipe 42a and the second delivery pipe 42b. In the fuel injection mechanism 40, the first delivery pipe 42 a is connected to the high-pressure fuel supply pipe 60, and the first delivery pipe 42 a and the second delivery pipe 42 b are connected by the connection pipe 43. The fuel pressure sensor 44 is provided in the first delivery pipe 42a, detects the fuel pressure in the delivery pipe 42, and outputs the detected fuel pressure to the ECU 70.

  The ECU 70 drives the high-pressure fuel pump 20 based on the fuel pressure detected by the fuel pressure sensor 44 so that the fuel pressure becomes a predetermined pressure, and the injection timing and the injection amount of the fuel injected from each injector 41 depending on the operating state. To control.

  In the fuel supply device 1 configured as described above, when the engine is started, the low-pressure feed pump 11 is driven to pressurize the fuel in the fuel tank 10, and the low-pressure fuel is supplied to the high-pressure fuel pump via the low-pressure fuel supply pipe 50. The high pressure fuel pump 20 further pressurizes the low pressure fuel, and can supply the high pressure fuel to the first delivery pipe 42a and the second delivery pipe 42b via the high pressure fuel supply pipe 60. 41 can inject the high-pressure fuel in the first delivery pipe 42a and the second delivery pipe 42b into the combustion chamber of the engine. At this time, the ECU 70 drives and controls the high-pressure fuel pump 20 based on the fuel pressure detected by the fuel pressure sensor 44, and maintains the fuel pressure in the first delivery pipe 42a and the second delivery pipe 42b at a predetermined pressure.

  Next, operations of the discharge valve 31, the relief valve 32, and the pilot valve 33 of the high-pressure fuel pump 20 will be described with reference to FIGS. FIG. 3 is a diagram for explaining the case where the high-pressure fuel pump 20 is operating normally, and FIG. 4 is a diagram for explaining the operation of the high-pressure fuel pump 20 when the fuel pressure is abnormal.

  In FIG. 3, when the high-pressure fuel pump 20 is normal, the relief valve 32 need not be opened by the surge pressure (pulsation fuel pressure) of the fuel during pressure feeding (see FIG. 5). In the present embodiment, as described above, the back pressure chamber 32c of the relief valve 32 and the inside of the discharge valve 31 are connected by the orifice 31e so that the relief valve 32 does not open due to surge pressure during pressure feeding. In addition, the pilot valve 33 is connected in series, and the opening pressure of the relief valve 32 is set to a predetermined pressure P3 (= the opening pressure P2 of the pilot valve 33—the surge pressure P1).

  During the pressure feeding, (1) when the discharge valve 31 is opened, the high pressure fuel is supplied from the high pressure fuel pump 20 to the first delivery pipe 42a and the second delivery pipe 42b through the high pressure fuel supply pipe 60. (2) Since the surge pressure at the time of pumping is instantaneous, the surge pressure is reduced by the orifice 31e and transmitted to the back pressure chamber 32c of the relief valve 32, so that the fuel pressure in the back pressure chamber 32c is not increased. 33 does not open. For this reason, the relief valve 32 does not open, and fuel does not relieve from the high pressure fuel supply pipe 60 (delivery pipe 42) to the low pressure fuel supply pipe 50b.

  In FIG. 4, when the fuel pressure of the high-pressure fuel pump 20 is abnormal, the fuel pressure of the delivery pipe 42 continues to rise. (2) When the fuel pressure in the back pressure chamber 32c of the relief valve 32 exceeds the valve opening pressure P2 of the pilot valve 33, the pilot valve 33 is opened. (3) When the pilot valve 33 is opened, the fuel pressure in the back pressure chamber 32c of the relief valve 32 is reduced, and (4) the pressure acting on the valve body 32a of the relief valve 32 is a predetermined pressure P3 (= opening of the pilot valve 33). When the pressure P2-surge pressure P1) is reached, the relief valve 32 is opened. As a result, (5) the fuel is relieved from the high pressure fuel supply pipe 60 (delivery pipe 42) to the low pressure fuel supply pipe 50b via the relief valve 32 and the pilot valve 33.

  As described above, according to this embodiment, the high-pressure fuel pump 20 includes the discharge valve 31 for keeping the fuel pressure of the fuel supplied to the fuel injection mechanism 40 constant, the inside of the discharge valve 31 and the passage 31d. Connected to the downstream side of the relief valve 32 and the low-pressure fuel supply passage 50b, and the valve opening pressure is set to a predetermined pressure P2 that is equal to or lower than the maximum operating fuel pressure of the fuel injection means 40. 33, the relief piping from the fuel injection mechanism 40 to the fuel tank 10 can be eliminated, and the fuel having an abnormal fuel pressure can be relieved with a low-cost configuration.

  Further, according to the present embodiment, the inside of the discharge valve 31 and the back pressure chamber 32c of the relief valve 32 are connected by the orifice 31e, and the valve opening pressure P3 of the relief valve 32 is changed to the valve opening pressure P2-surge of the pilot valve 33. Since the pressure P1 is set, it is possible to prevent the relief valve 32 from being opened due to the surge pressure (pulsation fuel pressure) of the fuel during pressure feeding.

  In the above embodiment, the case where the present invention is applied to an in-cylinder direct injection type 6-cylinder gasoline engine mounted on an automobile has been described. The present invention is not limited to this, and can be applied to a gasoline engine having any other number of cylinders. Further, the present invention is not limited to a gasoline engine, but can be applied to other internal combustion engines such as a diesel engine. Furthermore, the engine to which the present invention is applicable is not limited to an automobile engine.

  Further, the configurations and connection forms of the discharge valve 31, the relief valve 32, and the pilot valve 33 are not limited to the above-described embodiments, and other configurations and connection forms may be employed.

  As described above, the high-pressure fuel pump and the fuel supply device for the internal combustion engine according to the present invention can be widely used for various high-pressure fuel pumps that pump fuel at high pressure.

1 is a schematic configuration diagram of a fuel supply device for an internal combustion engine according to an embodiment of the present invention. It is a figure which shows schematic structure of the discharge valve of a high pressure fuel pump, a relief valve, and a pilot valve. It is a figure for demonstrating the case where the high pressure fuel pump is operating normally. It is a figure for demonstrating the operation | movement at the time of the fuel pressure abnormality of a high pressure fuel pump. It is a figure for demonstrating the fuel pressure of each part of the conventional fuel supply apparatus.

Explanation of symbols

1 Fuel Supply Device 10 Fuel Tank 11 Low Pressure Feed Pump (Low Pressure Pump)
12 Low pressure regulating valve 20 High pressure fuel pump (high pressure pump)
21 Suction port 22 Discharge port 23 Casing 24 Plunger 25 Pressure chamber 26 Spill valve 27 Spring 28 Solenoid 29 Cam 30 Camshaft 31 Discharge valve 32 Relief valve 33 Pilot valve 40 Fuel injection mechanism (fuel injection means)
41 Injector 42 Delivery pipe 42a First delivery pipe 42b Second delivery pipe 44 Fuel pressure sensor 50 Low pressure fuel supply pipe (low pressure passage)
60 High-pressure fuel supply pipe (high-pressure passage)
70 ECU

Claims (4)

In a high-pressure pump that pressurizes fuel supplied through a low-pressure passage in a pressurizing chamber by reciprocation of a plunger and pumps the fuel to a fuel injection unit through a high-pressure passage
A discharge valve for keeping the fuel pressure of the fuel supplied to the fuel injection means constant;
A relief valve connected to the inside of the discharge valve via a passage;
A pilot valve connected between the downstream side of the relief valve and the low pressure passage, the valve opening pressure of which is set to be equal to or lower than the maximum operating fuel pressure of the fuel injection means;
A high-pressure pump comprising: Connecting the inside of the discharge valve and the back pressure chamber of the relief valve with an orifice;
The high-pressure pump according to claim 1, wherein a valve opening pressure of the relief valve is set to a valve opening pressure-surge pressure of the pilot valve. A low-pressure pump capable of pressurizing and feeding fuel to a predetermined feed pressure;
A high-pressure pump that pressurizes and feeds fuel supplied from the low-pressure pump in a pressurizing chamber by reciprocation of a plunger;
Fuel injection means capable of injecting fuel pressurized by the high-pressure pump into a combustion chamber of an internal combustion engine;
A low-pressure passage connecting the low-pressure pump and the high-pressure pump;
A high-pressure passage connecting the high-pressure pump and the fuel injection means;
With
The high-pressure pump is
A discharge valve for keeping the fuel pressure of the fuel supplied to the fuel injection means constant;
A relief valve connected to the inside of the discharge valve via a passage;
A pilot valve connected between the downstream side of the relief valve and the low pressure passage, the valve opening pressure of which is set to be equal to or lower than the maximum operating fuel pressure of the fuel injection means;
A fuel supply device for an internal combustion engine, comprising: Connecting the inside of the discharge valve and the back pressure chamber of the relief valve with an orifice;
4. The fuel supply device for an internal combustion engine according to claim 3, wherein a valve opening pressure of the relief valve is set to a valve opening pressure-surge pressure of the pilot valve.

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