WO2000057051A1

WO2000057051A1 - High-pressure plunger pump

Info

Publication number: WO2000057051A1
Application number: PCT/JP2000/001746
Authority: WO
Inventors: Kazuo Araki; Yukihiro Shoji; Kenichi Katoh; Yuji Egami
Original assignee: Nachi-Fujikoshi Corp.
Priority date: 1999-03-23
Filing date: 2000-03-22
Publication date: 2000-09-28
Also published as: GB0027159D0; GB2352780A; DE10081174T1

Abstract

A high-pressure plunger pump for high-pressure fuel pump capable of varying a pump discharge rate thereof, wherein a small back pressure chamber (62) is provided to close the end parts of sliding holes (8, 108, 208) for suction check valve discs (51, 151, 251), the small back pressure chamber (62) communicates with a feed fuel path (4) selectively by opening and closing its port hole (61) by drive parts (71, 471) of small solenoid switching valves (7, 407) and, when the suction check valve discs are operated, the feed fuel discharged through the port hole (61) of the small back pressure chamber (62) is discharged to a suction port (26) of a pump chamber (2) so as to replace the feed fuel inside the small back pressure chamber (62) sequentially with new one, whereby, because a small solenoid switching valve may be used, a high-speed response is enabled, production cost can also be minimized, follow-up to electric signals can be made accurate, and a pump discharge can be controlled precisely.

Description

Description High pressure plunger pump Technical field

The present invention relates to a high-pressure plunger and a high-pressure plunger pump capable of variably controlling a discharge rate suitable for controlling a high-pressure fluid, and more particularly to a control method of a high-pressure plunger-pump, for example, a discharge rate for pumping high-pressure fuel into an accumulator or a common rail. The present invention relates to a variable discharge rate control mechanism for a high-pressure plunger pump that can be used for a variable high-pressure fuel pump. Background art

As a fuel injection device that supplies fuel to diesel engines and gasoline engines, high-pressure fuel is stored in a pressure accumulator or a pressure accumulating pipe called a common rail shown in FIG. 7, and this pressure accumulating fuel is injected into the engine through an electromagnetic injector. A high-pressure fuel pump used in the system is disclosed in Japanese Patent Application Laid-Open Nos. 6-257533 and 1-73166.

In the conventional high-pressure fuel pump described in Japanese Patent Application Laid-Open No. 6-257533, a sub-valve directly driven by a switching solenoid valve opens and closes a port of a back pressure chamber of a suction check valve body, thereby causing a back pressure. The suction check valve body hates the main valve chamber according to the pressure difference between the main valve chamber and the pump chamber and the biasing force of the main valve spring, thereby controlling the main valve chamber and the main valve chamber. The effective pumping stroke in the pumping stroke of the pump plunger is adjusted by opening and closing the pump chambers and adjusting the valve closing timing of the suction chuck. Disclosure of the invention

However, for example, as in the case of internal combustion engines for vehicles, the operating conditions change significantly with time, high-speed rotation, high pressure fuel pumps with pressures of 200 to 400 MPa, etc. When an increase in stroke is required, this type of suction check valve has a large auxiliary that is directly driven by the switching solenoid valve. As a result, a large switching solenoid valve was required, and there were problems with high-speed response and stable operation.

The object of the present invention has been made in view of the above-described problems. In spite of an increase in the size and speed of an engine, the size of a switching solenoid valve is reduced, and wear and leakage of a valve body and a valve seat of the switching solenoid valve are reduced. The object is to provide a high-pressure plunger pump that is a high-pressure fuel pump that can prevent high-speed response, achieve low production cost, accurately follow electric signals, and precisely control the pump discharge rate. .

(1) In order to achieve the above object, the present invention relates to a pump plunger formed in a pump housing and reciprocating via a cam mechanism urged by a spring force, and a pump pressurized by the pump plunger. A high-pressure plunger pump pumped by a suction check and a discharge valve connected to a discharge port of the pump chamber, which are disposed at a suction port of the pump chamber and communicate with the feed fuel passage. A small back pressure chamber having a main body for closing the sliding hole of the suction check valve housing into which the check valve element is fitted is provided. A port hole communicating with the fuel passage, wherein the port hole is selectively communicated with the feed fuel passage by opening and closing a drive unit of the small electromagnetic switching valve; When the suction check valve body is operated, the switching valve is operated by an electric signal given in synchronization with the stroke of the pump plunger, so that the drive unit of the switching valve closes the port hole of the small back pressure chamber, Controlling the valve opening position even if it receives the check valve spring force and the pressure of the pump chamber, which urges the suction check valve body in the closing direction, thereby making the pump discharge amount variable, and The fuel passage communicates with a suction port of the pump chamber, and when the suction check valve body operates, feed fuel discharged from a port hole of the small back pressure chamber is supplied to the suction port of the pump chamber. The high pressure plunger pump is characterized in that the fuel is discharged so that the feed fuel in the small back pressure chamber is sequentially replaced. In this case, the small port hole of the small back pressure chamber, which closes the end of the sliding hole of the suction check valve body, is pilot operated by a small solenoid-operated switching valve, and suction is performed by the pressure generated in the compression stroke of the pump plunger. Choi Since the force against the force to close the lock valve can be strengthened and a small solenoid-operated switching valve is sufficient, high-speed response is possible, the manufacturing cost is kept low, and precision with respect to electrical signals is reduced. It is possible to follow up, control the pump discharge rate precisely, and feed the fuel discharged from the port of the small back pressure chamber to the suction port of the pump chamber when the suction check valve is activated. The feed fuel in the back pressure chamber is sequentially replaced, and more precise pump discharge control can be performed.

(2) In the above (1), preferably, the small back pressure chamber has an inner diameter smaller than the inner diameter of the sliding hole, and has a small volume.

Thus, by operating the pilot by the small solenoid-operated directional control valve, it is possible to further increase the force that resists the force that closes the suction check due to the pressure generated in the compression stroke of the pump plunger. Can be a small electromagnetic switching valve.

(3) In the above (2), preferably, both surfaces having different taper angles from the taper angles of the seal portions are provided between the seal portions of the pump housing and the suction check valve housing for closing the pump chamber. A pump comprising: a hollow metal spring receiver having a double-sided sealing surface having a taper angle formed therein; and a suction check valve spring disposed between a large diameter portion of the suction check valve body and the spring receiver. The pressure oil in the room can be sealed to the seal part of the pump housing and the seal part of the suction check valve housing.

This reduces the size of the pump chamber which the pump housing and the suction check valve housing shut off, reduces leakage of pressurized oil, and receives each of the seal portions with a double-sided sealing surface having a different double-sided taper angle. Thus, since the sealing portions are in line contact with each other, processing accuracy such as flatness and surface roughness is not required, and the holding force is small, so that the structure is completely sealed.

(4) In the above (3), preferably, the material of the hollow metal spring receiver having the double-sided sealing surfaces is made of a material softer than the hardness of the material of each seal portion of the pump housing and the suction valve housing. By deforming the seal parts of the suction check valve, the paging and the pump housing, it is possible to more reliably seal the pressure oil in the pump chamber and to suppress a decrease in volumetric efficiency.

(5) In the above (4), preferably, the suction check valve housing slides. The cylindrical portion of the suction check valve body that fits into the hole has substantially the same diameter as the large-diameter portion, thereby facilitating processing accuracy.

(6) In the above (5), preferably, a hollow seal ring member having a double-sided sealing surface having a double-sided taper angle between the suction check valve housing of the suction check valve and the cup-shaped small back pressure chamber main body. Since the small back pressure chamber is provided, the small back pressure chamber can be more securely sealed from the pump chamber, and a decrease in volumetric efficiency can be suppressed.

(7) In the above (1) or (3), preferably, the switching valve is a NO (normally open) type switching valve, and when an electric signal is ON, a driving portion of the switching valve is connected to the small-back pressure chamber. The port hole was closed, and when the electric signal was turned off, the drive unit of the switching valve opened the port hole of the small back pressure chamber so as to communicate with the feed fuel passage.

With this configuration, when the pump plunger is in the suction process, the small back pressure chamber that communicates with the sliding hole of the suction check valve body communicates with the low-pressure pressurized feed fuel passage. The drive unit of the small electromagnetic switching valve that is activated by an electric signal from the ECU is open. Due to the differential pressure between the suction negative pressure and the feed pressure generated by the suction operation due to the expansion of the volume of the pump chamber accompanying the movement of the pump brander, the suction chuck valve is piled on the spring force attached to the suction chuck valve. The sheet is pushed open and the fluid is guided from the suction port to the pump chamber to fill the pump chamber. At this time, the suction check valve will automatically open. ^ The spring attached to the suction check valve will cause the differential pressure between the pressure on the feed side and the pressure in the pump chamber to be determined by the spring force. Pressure, so that the influence of the flow caused by the inflow and outflow of the feed fluid into and out of the small back pressure chamber for controlling the suction and discharge of the pump chamber that generates high pressure and the suction check valve element is reduced. Operation is stabilized. Another advantage is that the opening / closing timing of the suction check valve can be changed with respect to the electric signal from the ECU by changing the spring f.

(8) In the above (1) or (3), preferably, the switching valve is an NC (normally closed) type switching valve, and when the electric signal is ON, the drive unit of the switching valve closes the port hole of the small back pressure chamber. It may be so arranged that it communicates with the feed fuel passage so that the drive unit of the switching valve closes the port hole of the small back pressure chamber when the electric signal is OFF.

(9) In the above (1) or (3), preferably, the pump plunger When the stroke position is detected, the speed of the reciprocating stroke movement of the pump plunger is near the highest speed, or is set in advance according to the rotation near the time when the suction check valve body reaches the maximum suction stroke. By energizing (or de-energizing) the switching valve with the delay time or timing, the port of the small back pressure chamber is closed, so that the seat portion of the suction check valve is kept open. You may. With this configuration, the suction check valve element has the property of having the maximum stroke near the point where the speed of the suction stroke movement of the pump plunger is the fastest or near the point where the suction check ^ reaches the maximum suction stroke. This is a fixed timing determined according to the shaft rotation speed, and is called delay time or delay timing. When the switching valve is energized (or de-energized) near this maximum stroke and the fluid in the small back pressure chamber that communicates with the sliding hole of the suction check valve is closed, the seat of the suction check ^ opens. It is kept as a valve. At this time, the rotation of the input camshaft or the position of the plunger is detected, and the small electromagnetic switching valve is driven to open and close the port of the small back pressure chamber with a delay timing or delay time set in advance by the ECU. This makes it possible to make the discharge amount variable, and it is necessary to precisely and variably control the discharge flow rate, which is significantly different from conventional mechanisms.

When the switching valve is energized (or de-energized) and the port is opened, the suction check valve is pressed by the spring force that presses the suction check valve to the sheet side and the pressure generated in the pump plunger by the compression of the pump plunger. The valve body moves to the seat side of the suction check valve housing and sits down, becoming a seat state, and the pump chamber is sealed. When the pump plunger further strokes, the pressure in the pump chamber further rises, and when the pressure in the pump plunger chamber becomes higher than the opening pressure of the discharge check valve, the pressurized fluid is discharged through the discharge check valve. At this time, it is possible to stop the energization of the switching valve from the ECU at any time during the stroke of the compression stroke. Since the amount of fluid to be compressed changes accordingly, it is possible to control the variable discharge flow rate.

(10) Preferably, a pump plunger, which is formed in the pump housing and is reciprocated by a spring force and reciprocates via a force mechanism, a pump chamber pressurized by the pump plunger, and a suction port of the pump chamber Suction valve connected to the feed fuel passage and a discharge port connected to the discharge port of the pump chamber. A back valve having a cap-shaped small back pressure chamber body for closing an end of a sliding hole of a suction check valve housing in which the suction check valve body is fitted. The small back pressure chamber has a port hole communicating with the feed fuel passage, and the port hole is selectively communicated with the feed fuel passage by opening and closing a drive unit of the small electromagnetic switching valve. When the suction check valve body is operated, the switching valve is operated by an electric signal given in synchronization with the stroke of the pump plunger, so that the driving portion of the switching valve operates the small back pressure chamber. By closing the port hole, the suction check is urged in the closing direction.Control is performed so that the valve opening position can be maintained even when the check valve spring force and the pressure in the pump chamber are received. The pump discharge amount is variable, and the feed fuel passage is communicated with a suction port of the pump chamber. When the suction chinic operates, the feed fuel discharged from the port hole of the small back pressure chamber is discharged. Is discharged to the suction port of the pump chamber so that the feed fuel in the small back pressure chamber is sequentially replaced. The small back pressure chamber has an inner diameter smaller than the inner diameter of the sliding hole, and has a small volume. A double-sided sealing surface having a double-sided taper angle having a taper angle different from the taper angle of each of the seal portions is provided between each seal portion of the pump housing and the suction check valve housing for closing the pump chamber. And a suction check valve spring disposed between the formed hollow metal spring receiver and the large-diameter portion and the spring receiver. The seal part of the jig and the seal part of the suction chuck valve housing can be sealed, and the material of the hollow metal spring receiver having the double-sided sealing surface is made of a material of the pump housing and the suction chuck valve housing. The cylindrical portion of the suction check valve body, which is made softer and harder than the hardness of the material of the pipe portion and is fitted into the sliding hole of the suction check valve housing, has substantially the same diameter as the large diameter portion. A high-pressure plunger pump having a hollow sealing ring member having a double-sided taper angle and a double-sided taper angle is provided between the suction check valve housing of the check valve and the main body of the small back pressure chamber. As a result, the configuration and effects described in (1) to (6) are obtained. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is an enlarged sectional view of a main part of a high-pressure plunger pump according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of a high-pressure plunger pump according to a second embodiment of the present invention.

FIG. 3 is a schematic sectional view of the entire high-pressure plunger pump according to the third embodiment of the present invention.

FIG. 4 is an enlarged sectional view of a main part of a suction check valve and a small electromagnetic switching valve of a high-pressure plunger pump according to a fourth embodiment of the present invention.

FIG. 5 is an enlarged sectional view of a main part of a suction check valve and a small electromagnetic switching valve of a high-pressure plunger pump according to a fifth embodiment of the present invention.

FIG. 6 is an explanatory diagram showing the concept of delay time / timing.

FIG. 7 is a block diagram showing a schematic configuration of a common rail fuel injection device using the high-pressure plunger pump of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an enlarged sectional view of a main part of a high-pressure plunger pump according to a first embodiment of the present invention. This high-pressure plunger pump 1 is a conventional common-rail type fuel injection device shown in FIG. It is used as a high-pressure fuel pump of a hydraulic pressure generator of the type. In the conventional common rail fuel injection device shown in FIG. 7, fuel in a fuel tank 11 is sent by a fuel feed pump 12 to a high-pressure plunger pump 13 which is a high-pressure fuel pump. The fuel sent from 12 is pressurized to high-pressure fuel of about 100 MPa corresponding to the injection pressure, and this high-pressure fuel is sent to a common rail 16 via a discharge check valve 14 and a discharge pipe 15. A plurality of distribution pipes 17 are connected to the common rail 16, and each distribution pipe 17 is connected to an electromagnetic injector 19 installed in each cylinder of the engine 18. When the electromagnetic control valve 20 is actuated, the electromagnetic injector 19 opens an injector (not shown), and high-pressure fuel in the common rail 16 is supplied to each cylinder of the engine 18 via the injector 19. It is designed to be injected. Electromagnetic control of injector 19 The valve 20 is controlled by an electronic control unit ECU 21. The ECU 21 receives information on the engine speed and load state from, for example, the engine speed sensor 22 and the load sensor 23, determines the operating state of the engine based on these signals, and optimizes the engine according to the operating state of the engine. An injection timing and an injection amount are calculated and a control signal is issued to the electromagnetic control valve 20. Therefore, an optimal injection timing and an optimal injection amount of fuel are injected into each cylinder of the engine 18 according to the operating state of the engine. Also, the fuel consumed by the injection drops in the common rail 16 and the fuel pressure in the common rail 16 must be constantly maintained at a pressure corresponding to the injection pressure to compensate for the consumption. There is. For this reason, the fuel of the above consumption is supplied from the high-pressure plunger pump 13 to the common rail 16. That is, the common rail 16 is provided with a pressure sensor 24 for detecting the fuel pressure in the common rail, and the ECU 21 sends a command signal to the high-pressure plunger pump 13 by a signal from the pressure sensor 24, The discharge amount of the plunger pump 13 is controlled. Therefore, the high-pressure plunger pump 13 must be a pump capable of controlling the discharge amount according to the engine load and the number of revolutions. For this reason, this type of high-pressure pump is described in each of the above publications. Is adopted.

FIG. 1 shows a high-pressure plunger pump 1 according to a first embodiment of the present invention, which is reciprocated via a cam mechanism (not shown) urged by a spring force (not shown) formed in a pump housing 50. The pump plunger 3 that moves, the pump chamber 2 to which the pump plunger 3 pressurizes, the suction check valve body 51 disposed in the suction port 26 of the pump chamber 2 and communicated with the feed fuel passage 4, and the discharge port 27 of the pump chamber 2 A pump is actuated by the discharge check valve 30 connected to. The small back pressure chamber main body 6 is provided with a small volume pressure-type back pressure chamber body 6 that closes the end of the sliding hole 52 of the suction check valve nosing 50 into which the suction check valve 51 is fitted. Is the feed fuel passage

The small back pressure chamber 62 in the small back pressure chamber main body 6 has an inner diameter smaller than the inner diameter of the sliding hole 8. The small back pressure chamber 62 in the small back pressure chamber body 6 is selectively connected to the feed fuel and the fuel passage 4 by opening and closing the port hole 61 by opening and closing the rod 71, which is the drive unit of the small electromagnetic switching valve 7. To be. The small solenoid-operated switching valve 7 has a solenoid coil 72, a fixed magnetic pole 73 fixed to a pressure-resistant tube 76, and a rod 71, which is a driving unit, fixed by a spring 75. It has a movable magnetic pole 74 that is energized and reciprocates within a pressure-resistant tube 76. When the suction check valve element 51 is operated, the switching valve 7 is operated by an electric signal (not shown) provided in synchronization with the stroke of the pump plunger 3, so that the rod 71, which is the driving unit of the switching valve 7, has a small height. By closing the port hole 61 of the pressure chamber 62, control is performed so that the valve can be maintained in the open position even when receiving the force of the check valve spring 54 that urges the suction check valve body 51 in the closing direction and the pressure of the pump chamber 2. As a result, the pump discharge amount is variable, and the feed fuel passage 4 is communicated with the suction port 26 of the pump chamber 2. When the suction check valve body 51 is operated, the port hole 61 of the small back pressure chamber 62 is operated. Is discharged to the suction port 26 of the pump chamber 2 so that the feed fuel in the small back pressure chamber 62 is sequentially replaced. In the lower part of the pump housing 50 in the drawing, a force is formed, for example, as shown at 64 in FIG. The suction check valve spring 54 is guided by a spring guide 53 supported by a snap ring 59 on the suction check valve body 51 and urges the suction check # 51 upward. A clearance is provided between the cylindrical portion 56 of the suction check valve element 51 and the sliding hole 8 that slides so that even if the pressure in the small back pressure chamber 62 increases, the amount of leakage is small. The small electromagnetic switching valve 7 shown in Fig. 1 is N 1 type

(Normal 'open type') Switching valve. When the electric signal is ON, the movable electrode 74 is stuck to the fixed electrode 73 by the force of the spring 75, and the rod 71 of the switching valve 7 is connected to the small back pressure chamber 62. The port hole 61 is closed, and when OFF, the rod 71 is returned upward together with the movable electrode 74 by the force of the spring 74 so that the port hole 61 of the small back pressure chamber 62 communicates with the feed fuel passage 4. ing.

In operation, the feed fuel passage 4 provided in the pump housing 28 is turned on by a fuel pump (not shown) with a key switch (not shown) turned on, and a pressure of about 0.3 MPa set by a relief valve (not shown) before the engine is started. Has been added. When the pump plunger 3 descends, the negative pressure in the pump chamber 2 overcomes the force of the suction check valve spring 54, and feed fuel is introduced into the pump chamber 2 from the suction port 26. When the pump plunger 3 rises while the port hole 61 of the small back pressure chamber 62 is open, the large diameter portion 55 of the suction check valve body 51 closes the suction port 26 and is pressurized in the pump chamber 56. The high-pressure fuel pushes and opens the check valve body 32 of the discharge check valve 30, whereby the high-pressure fuel pressurized in the pump chamber 56 is sent to the common rail 16 shown in FIG. In the present invention configured as described above and shown in FIG. 1, the small port hole 61 of the small back pressure chamber 62 having a small volume closing the end of the sliding hole 8 of the suction check valve body 51 is connected to the small electromagnetic switching valve 7. By performing the pilot operation, the force generated in the compression stroke of the pump plunger 3 can increase the force against the force for closing the suction check valve element 51, and the small electromagnetic switching valve 7 can be used. , High-speed response, low manufacturing cost, precise tracking of electrical signals, precise pump discharge control, and small back pressure chamber when the power and suction The feed fuel discharged from the port hole 61 of 62 is sent out to the suction port 26 of the pump chamber 2, and the feed fuel in the small back pressure chamber 62 is sequentially replaced. Precise pump discharge control Can be.

FIG. 2 is an enlarged sectional view of a main part of a high-pressure plunger-pump according to a second embodiment of the present invention. In the present embodiment, each taper different from the taper angle of each of the seal portions 89 and 92 is provided between the seal portions 89 and 92 of the pump housing 150 and the suction check valve housing 152 for closing the pump chamber 2. Hollow metal spring receiver 88 formed with double-sided taper angled double-sided sealing surfaces 90, 91 and suction check valve spring 84 disposed between large-diameter portion 155 and spring receiver 88. The pressure oil in the pump chamber 2 can be sealed to the seal portions 89 and 92 of the pump nozzle 150 and the suction check valve housing 152.

According to the embodiment shown in FIG. 2, the pump chamber 150 and the seal chambers 89 and 92 of the suction check valve housing 152 are closed to reduce the size of the pump chamber, which reduces the leakage of pressurized oil. By receiving on both sides sealing surfaces 90, 91 having different taper angles with different taper angles, each sealing part 89, 92 comes in line contact, so processing accuracy such as flatness and surface roughness is not required. In addition, the holding force is small and the structure is completely sealed.

In the embodiment of FIG. 2, the spring receiver 88 has a taper angle (25 to 45 °) on both sides, and the taper angle is larger than the taper angle (2 to 10 °) of the pump housing 150 and the check valve housing 152. The check valve housing 152 and the pump housing 150 are sealed by the sealing portions 89 and 92 inside the pump housing 150 by the tightening force of the screw portions 93 of the pump housing 150. Spring receiver The material hardness of 88 is set to be lower (300 to 450 HV) than the hardness (HV 1000) of the pump housing 150 and the check valve housing 152, which causes deformation at each seal part 89, 92 to ensure Sealing can suppress a decrease in volumetric efficiency. FIG. 3 is a schematic sectional view of the entire high-pressure plunger pump according to the third embodiment of the present invention. 2 except that the cylindrical portion 256 that fits into the sliding hole 208 of the suction check valve housing 205 of the suction check valve 205 has substantially the same diameter as the large-diameter portion 155. It has the same structure as. A cylinder hole 66 is installed in the pump housing 250 to convert rotational motion into linear motion by rotation of a cam 64 fixed to a shaft 63, and the pump plunger 3 can reciprocate in the cylinder hole 66. It is inserted in. When the shaft 63 is rotated by an external power (not shown), the outer ring 165 is rotated via the bearing 65 mounted on the cam 64, and the pump plunger 3 in contact with the bearing 65 is reciprocated in the cylinder hole 66. . The reciprocating stroke of the pump plunger 3 is determined by the height difference of the cam 64. 12 is a feed pump and 67 is a relief valve. In the suction check valve 205 shown in FIG. 3, the cylindrical portion 256 that fits into the sliding hole 208 of the check valve housing 252 has substantially the same diameter as the large-diameter portion 155, thereby facilitating processing accuracy. The upper part of Fig. 3 shows a state in which the pump plunger 3 is at the bottom dead center, and the fluid in the pump chamber 2 is before compression starts. The lower part of FIG. 3 shows a state in which the pump plunger 3 is at the top dead center, and the fluid in the pump chamber 2 is discharged from the discharge port 27 through the discharge check valve 30 to a residual pressure state. Therefore, the large-diameter portion 256 of the suction check valve body 251 is seated on the seating portion of the check valve housing 252 to close the discharge port 27. At this time, the small electromagnetic switching valve 7 is not supplied with the electric signal from the ECU 21 in FIG. 7 and the port hole 61 of the small back pressure chamber 62 is open. Therefore, the fluid in the small back pressure chamber 62 communicates with the feed fuel passage 4.

When the pump plunger 3 starts rising from the lower state in FIG. 3 and moves to the suction stroke, the volume of the pump chamber 2 increases and the pressure decreases. At this time, the pressure of the pump chamber becomes lower than the pressure of the feed-side suction port 27. When the pressure difference is greater than the clamping pressure set by the force of the spring 254 attached to the suction check valve 251, the suction check valve 251 is pushed open. Therefore, the large-diameter sheet portion 255 of the suction check valve element is separated from the seating portion, and the flow of the feed-side suction port 27 is reduced. The body flows into the pump chamber 2. When the pump plunger 3 further continues the suction process, the suction check valve element 251 reaches the maximum suction stroke near the point where the speed of the stroke movement of the pump plunger 3 becomes the highest. The switching valve 7 is energized by an electric signal from the ECU 21 at the timing when the suction check valve body 251 reaches the maximum suction stroke, and the small back pressure chamber 62 communicating with the suction check valve body 251 is turned on. By closing 61, the large-diameter portion 255 of the suction tip ^: 251 is kept open. That is, the stroke position of the pump plunger 3 is detected, and the rotation of the pump plunger 3 near the maximum reciprocating stroke speed or near the suction check ^ 251 reaching the maximum suction stroke is determined according to the rotation. By energizing (or de-energizing) the switching valve with a preset delay time or timing and closing the port hole 61 of the small back pressure chamber 62, the suction chuck ^: the large-diameter portion 255 of the 251 remains open It was kept.

Here, the timing is the time point at the stroke position corresponding to the movement of the pump plunger. The stroke position of the pump plunger such as the rotation angle of the cam shaft and the rotation angle of the input shaft is detected and converted into an electric signal. It is something that can be processed to specify the time point. Figure 6 shows an example of the delay time. Figure 6 (1) shows the concept of repetition of the suction and pumping steps in the stroke process of the pump plunger. The displacement X indicates the stroke position. FIG. 6 shows one cycle of the repetition of the suction step and the pumping step of the pump plunger. Figure 6 (2) shows an example of the characteristics of the automatic opening and closing of the suction check valve when the switching valve drive is open. Fig. 6 (3) shows a state in which the drive unit of the switching valve is closed by an electric signal to close the small back pressure chamber and the suction check valve body is kept open near the maximum stroke of the suction chuck. Similarly, FIG. 6 (4) shows a state in which the drive unit of the switching valve is closed by an electric signal to close the small back pressure chamber near the maximum stroke of the suction check valve body, and the suction check valve body is kept open. Indicates that the open state ratio can be changed by the ON time (or timing).

When the suction chuck 251 reaches the maximum suction stroke, the switching valve 7 is energized and the port 61 of the small back pressure chamber 62 communicating with the suction check valve 251 is closed.

When -3 reaches the top dead center and moves downward, the volume of pump chamber 2 is increased. The pressure decreases and the pressure in the pump chamber 2 increases, increasing the pressure. In such a compression stroke, when the pressure in the pump chamber 2 rises and becomes higher than the pressure Pf on the feed side and the pressure obtained by adding the force of the suction check valve spring 254, the flow pressurized in the pump chamber 2 is increased. The body is pushed back to the feed side pressurized by the feed pump 212 through the communication hole 94, the gap between the large diameter portion 255 and the seating portion, the suction port 27 and the feed fuel passage 4. The pressure of the feed fuel passage 4 is kept constant by the relief valve 67 connected to the feed fuel passage 4. Therefore, even if the fuel is pressurized in the pump chamber 2, the feed fuel is not pumped to the common rail 16 shown in FIG. 7 through the discharge port 27 and the discharge tick valve 30.

FIG. 4 is an enlarged cross-sectional view of a main part of a suction check valve and a small electromagnetic switching valve of a high-pressure plunger pump according to a fourth embodiment of the present invention. In particular, an NC (normally closed) switching valve is shown. Indicates 401. The small electromagnetic switching valve 7 shown in Figs. 1 and 3 is a NO type (normally open type) switching valve. When the electric signal is ON, the rod 71 of the switching valve 7 is connected to the port hole 61 of the small back pressure chamber 62. And the port hole 61 of the small back pressure chamber 62 communicates with the feed fuel passage 75 when it is OFF. On the other hand, the small electromagnetic switching valve 407 in FIG. 4 is an NC type switching valve, and when the electric signal is ON, the opening 471 of the switching valve 407 feeds the port hole 61 of the small back pressure chamber 62 to the fuel passage. It communicates with 404 and closes the port hole 61 of the small back pressure chamber 62 when it is OFF. The fixed magnetic pole 473 is fixed to a pressure-resistant tube 476, and the movable magnetic pole 474 is fixed to a rod 471. NC type (normally closed type) The switching valve must also be able to control the opening and closing timing of the suction pick-up valve in response to the electric signal so that the discharge flow rate corresponds to those shown in Figs. 1 and 3 Needless to say.

FIG. 5 is an enlarged sectional view of a main part of a suction check valve and a small electromagnetic switching valve of a high-pressure plunger-pump according to a fifth embodiment of the present invention. The suction check valve 505 of the fifth embodiment is a hollow seal ring member having double-sided sealing surfaces 97 and 98 having double-sided taper angles between the check valve housing 252 and the cup-shaped small back pressure chamber body 6. 95 is provided. 96 is a hollow hole. With such a configuration, the small back pressure chamber 62 is more reliably sealed with respect to the pump chamber 2 and a reduction in volumetric efficiency is suppressed, the electric signal can be followed more precisely, and the pump discharge amount can be precisely controlled. Industrial applicability

According to the present invention, in a variable discharge amount control system of a high pressure plunger-pump which can be used for a variable discharge high pressure fuel pump for pumping high pressure fuel into an accumulator or a common rail, a pilot operation is performed by a small electromagnetic switching valve. , High-speed response is possible, manufacturing costs are kept low, it is possible to precisely follow the electric signal, it is possible to precisely control the discharge rate of the pump, and when the suction check valve element operates, the small back pressure chamber po The feed fuel discharged from the through hole is sent to the suction port of the pump chamber, and the feed fuel in the small back pressure chamber is sequentially replaced, so that the pump discharge amount can be controlled more precisely.

Claims

The scope of the claims

1. The pump plunger (3) and the pump plunger (3) formed in the pump housing (50) and reciprocated by the spring (9) force and reciprocating via the cam mechanism (9) pressurize. Pump chamber (2), suction check valve (51, 151, 251) and pump chamber (2) located at the suction port (26) of the pump chamber (2) and connected to the feed fuel passage (4) A discharge check valve (30) connected to a discharge port (27) of the high pressure plunger pump operated by the suction check valve body (51, 151, 251). A small back pressure chamber (62) having a cup-shaped small back pressure chamber body (6) for closing the end of the sliding hole (8, 108, 208) of (52, 152, 252) is provided. The small back pressure chamber (62) has a port hole (61) communicating with the feed fuel passage (4), and the port hole (61) is small. Opening and closing of the drive unit (71, 471) of the electromagnetic switching valve (7, 407) enables selective communication with the feed fuel passage (4), and the suction check valve body (51, 151, 251) When the switching valve (7, 407) is actuated by an electric signal given in synchronization with the stroke of the pump plunger (3) when the valve operates, the drive unit (71, 471) of the switching valve (7, 407) is actuated. By closing the port hole (61) of the small back pressure chamber (62), the suction check ^ (51, 151, 251) is urged in the closing direction (54, i54, 254). The pump discharge amount is variably controlled by controlling the valve opening position even when receiving the force of the pump chamber (2) and the pressure of the pump chamber (2). 2) is connected to the suction port (26). When the suction check valve operates, the fuel discharged from the port hole (61) of the small back pressure chamber (62) is discharged. High-pressure plunger pump but which is characterized in that is discharged to the suction port (26) of the pump chamber (2) is Fi once fuel in the small back pressure chamber (62) is adapted be successively replaced.

2. The high-pressure plunger pump according to claim 1,

The high-pressure plunger pump, wherein the small back pressure chamber (62) has an inner diameter smaller than the inner diameter of the sliding hole (8, 108, 208).

3. The high-pressure plunger pump according to claim 2,

The tape of each of the seals (89, 92) is inserted between the seals (89, 92) of the pump housing (150, 250) and the suction check valve housing (152, 252) which closes the pump chamber (2). A hollow metal spring receiver having a double-sided sealing surface (90, 91) having a taper angle on both sides having a different taper angle from the angle, and a large-diameter portion (155, 255) of the suction check valve body and a spring receiver ( 88), and a suction check valve spring (84) disposed between the pump housing (2) and the pump housing (50) and the suction check valve housing (52, 152, 252) A high-pressure plunger pump characterized by being able to seal against each seal part (89, 92).

4. The high-pressure plunger pump according to claim 3,

The hardness of the material of the spring receiver (88) is made softer than the hardness of the material of each seal portion (89, 92) of the pump housing (150, 250) and the suction check valve housing (152, 252). , A high-pressure plunger pump characterized by ensuring a seamlessness.

5. The high-pressure plunger pump according to claim 4

A high-pressure plunger pump, wherein a cylindrical portion (256) fitted into a sliding hole (208) of the suction check valve housing (252) has substantially the same diameter as the large-diameter portion.

6. The high pressure plunger pump according to claim 5,

The suction check valve (505) has a double-sided sealing surface (97, 98) having a double-sided taper angle between the check valve nozzle (252) and the cup-shaped small back pressure chamber body (6). A high-pressure plunger pump characterized by having a ruling member (95).

7. The high-pressure plunger pump according to claim 1 or 3,

The switching valve (7) is a NO (normally open) type switching valve, and when the electric signal is 〇N, the driving portion (71) of the switching valve closes the port hole (61) of the small back pressure chamber (62). When it is OFF, the drive part (71) of the switching valve (7) is positioned in front of the port hole (61) of the small back pressure chamber (62). A high-pressure plunger pump characterized in that it communicates with the feed fuel passage (4).

8. The high-pressure plunger pump according to claim 1 or 3, wherein the switching valve (407) is an NC (normally closed) type switching valve, and the switching valve when the electric signal is ON.

The drive section (471) of the (407) communicates the port hole (61) of the small back pressure chamber (62) with the feed fuel passage (4). A high-pressure plunger pump characterized in that the port hole (61) is closed.

9. The high pressure plunger pump according to claim 1 or 3,

Detecting the stroke position of the pump plunger (3), and near the point where the speed of the reciprocating stroke movement of the pump plunger is the highest, the suction chuck valve body (51, 151, 251) sucks the maximum. When the stroke reaches the stroke, the switching valve is energized (or de-energized) with a delay time or timing set in advance according to the rotation, and the port of the small back pressure chamber is closed, so that suction is performed. High pressure plunger pump characterized in that Check ^: is held open with respect to the seat part

10. The pump plunger (3) and the pump plunger (3) formed in the pump housing (50) and reciprocated via the cam mechanism (9) urged by the spring (9) Pump chamber (2) to be pressurized, suction check valve (51, 151, 251) and pump chamber (2) arranged in the suction port (26) of the pump chamber (2) and communicated with the feed fuel passage (4). ), A discharge check valve (30) connected to the discharge port (27), and a high-pressure plunger pump that performs a pumping operation with the suction check valve (51, 151, 251) fitted with the suction check valve. A small back pressure chamber (62) having a cup-shaped small back pressure chamber body (6) for closing an end of a sliding hole (8, 108, 208) of the housing (52, 152, 252); The small back pressure chamber (62) has a port hole (61) communicating with the feed fuel passage (4), and the port hole (61) is small. Magnetic switching valve by opening and closing drive unit (7,407) (71,471) are to be selectively communicating with Fi once fuel passage (4), suction check valve (51,151,251) When the switching valve (7, 407) is actuated by an electric signal given in synchronization with the stroke of the pump plunger (3) when the valve operates, the drive unit (71, 471) of the switching valve (7, 407) is actuated. By closing the port hole (61) of the small back pressure chamber (62), the check valve spring (54, 154, 254) that urges the suction check valve body (51, 151, 251) in the closing direction The pump discharge amount is variably controlled by controlling the valve opening position even when receiving the force and the pressure of the pump chamber (2), and the feed fuel passage (4) is connected to the pump chamber (2). ) Is connected to the suction port (26), and the feed fuel discharged from the port hole (61) of the small back pressure chamber (62) when the suction check valve body operates is supplied to the pump chamber. The fuel is discharged to the suction port (26) of (2) and the feed fuel in the small back pressure chamber (62) is sequentially replaced. Each seal portion of the pump housing (150, 250) and the suction check valve housing (152, 252) having an inner diameter smaller than the inner diameter of the sliding hole (8, 108, 208) and closing the pump chamber (2). A hollow metal formed between (89, 92) and a double-sided sealing surface (90, 91) having a double-sided taper angle having a different taper angle from the taper angle of each of the seal portions (89, 92). And a suction check valve spring (84) disposed between the spring receiver and the large diameter portion (155) and the spring receiver (88), and pressurized oil in the pump chamber (2) is supplied to the pump housing (2). 50) and each of the seal portions (89, 92) of the suction check valve housing (52, 152, 252), and the hardness of the material of the spring receiver (88) is as follows. 250) and the material of each seal (89, 92) of the suction check valve housing (152, 252) The cylindrical part (256) that fits into the sliding hole (208) of the suction check valve housing (252) is made of a material that is softer than the hardness of the large diameter part (155). The suction check valve (505) has substantially the same diameter, and has a double-sided tapered angle between the check valve housing (252) and the cup-shaped small back pressure chamber body (6). A high-pressure plunger pump characterized by comprising a hollow sealing ring member (95) having the following structure.