JP2004116531A - High pressure feed pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high pressure feed pump capable of easily and accurately controlling a pumping flow rate without causing enlargement of a device or an increase of electric power. <P>SOLUTION: Low pressure fluid is sucked into a pressure chamber 23 formed by an inner wall face of a cylinder 2 and a plunger 21 end face via low pressure passages 14, 51a-51b, 52, 46, and 74a-74c, and pressurized fluid is pumped into a high pressure passage 33. A check valve 4 opening and closing the passages to the pressure chamber 23 is provided between the low pressure passages and the pressure chamber 23, and a solenoid valve 6 controlling a flow rate of the low pressure fluid fed into the pressure chamber 23 is provided upstream of the check valve 4. Since a suction amount of the low pressure fluid is controlled by the solenoid valve 6 and all of the low pressure fluid sucked into the pressure chamber 23 via the check valve 4 is pressurized and pumped in the system, pumping speed can be positively and inexpensively controlled by a simple composition. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a high-pressure supply pump used for pressure-feeding a high-pressure fluid in, for example, a common rail injection system of a diesel engine.

コ モ ン A common rail injection system is known as one of the systems for injecting fuel into a diesel engine. In the common rail injection system, a common accumulator pipe (common rail) communicating with each cylinder is provided, and a high-pressure supply pump supplies a required flow of high-pressure fuel to the cylinder to maintain a constant fuel pressure in the accumulator pipe. ing. The high-pressure fuel in the pressure accumulation pipe is injected into each cylinder by an injector at a predetermined timing (for example, Japanese Patent Application Laid-Open No. 64-73166).

FIG. 17 shows an example of a high-pressure supply pump used for such an application. A plunger 92 driven by a cam (not shown) is reciprocally fitted into a cylinder 91, and the inner wall surface of the cylinder 91 is A pressure chamber 93 is formed by the upper end surface of the plunger 92. An electromagnetic valve 94 is mounted above the pressure chamber 93. The electromagnetic valve 94 has a valve body 96 that opens and closes a space between the low-pressure passage 95 and the pressure chamber 93 formed therein.

The valve body 96 is in the valve-opening position in a state where power is not supplied to the coil 97, and when the plunger 92 is lowered, the fuel flows from the low-pressure supply pump (not shown) through the low-pressure passage 95 and the gap around the valve body 96 to the pressure chamber. 93 is introduced. When the coil 97 is energized, the valve body 96 is attracted upward, and its substantially conical tip sits on the seat portion 98 to close the valve. At the same time, the fuel in the pressure chamber 93 is pressurized by the rise of the plunger 92, and is sent to the pressure accumulating pipe through the passage 99 provided on the side wall of the pressure chamber 93.

By the way, since the force in the valve closing direction acts on the valve body 96 by the fuel pressure in the pressure chamber 93 while the plunger 92 is rising, once the valve body 96 is closed once, the energization to the coil 97 is stopped. Does not open. For this reason, in the high-pressure supply pump having the above-described configuration, the flow rate sent to the pressure accumulation pipe is controlled by so-called pre-stroke control that controls the valve closing timing. That is, after the plunger 92 moves to the ascent stroke, the valve is not closed immediately, the valve is kept open until the fuel in the pressure chamber 93 reaches a predetermined amount, and excess fuel is released to the low-pressure passage 95 side. Thereafter, by closing the valve and starting pressurization, a required amount of pressurized fluid is pressure-fed to the accumulator pipe.

However, when the oil feed rate of the pump increases with an increase in the engine speed, there arises a problem that the valve body 96 closes (self-closes) regardless of the valve closing signal. This is because when the plunger 92 is raised, the valve body 96 directly receives the dynamic pressure of the fuel in the pressure chamber 93 at the lower end surface, and flows toward the low-pressure passage 95 from the gap between the valve body 96 and the seat portion 98. This is due to receiving a force in the valve closing direction due to the throttle effect of the fuel, and the flow rate control may not be properly performed.

対 策 As a countermeasure, it is conceivable to increase the operating stroke of the valve body 96 or increase the return spring force of the valve body 96, but in any case, the valve closing response is reduced. In order to maintain valve-closing response, it is necessary to increase the amount of power supplied to the coil or increase the physical size to increase the attraction force of the solenoid valve, which increases the power cost and manufacturing cost of the solenoid valve. There was a problem.

Further, in the high-pressure supply pump having the above-described configuration, the flow path to the pressure chamber 93 is opened and closed by the electromagnetic valve 94, and a certain time is required until the valve body 96 sits and closes the flow path in response to the valve closing signal. Therefore, usually, the operation response time is calculated in advance to control the valve closing timing. However, when the rotation speed of the engine increases and the oil feed rate of the pump increases, the opening and closing operation cannot be performed in time, and there is a possibility that sufficient control cannot be performed.

Therefore, an object of the present invention is to make it possible to easily and reliably control the flow rate of pressure-supplying to a pressure accumulating pipe even in a state where the engine speed is increased and the oil supply rate of the pump is high, and furthermore, the size of the apparatus is increased and the electric power is increased. It is not accompanied by. Another object of the present invention is to eliminate a problem such as a response delay caused by using an electromagnetic valve for opening and closing the flow path.

In the configuration of the first aspect of the present invention, the high-pressure supply pump is configured such that a plunger is inserted into the cylinder so as to be able to reciprocate, and a pressure chamber is formed by the inner wall surface of the cylinder and the end face of the plunger. The low-pressure fluid introduced from the passage is pressurized by the reciprocating motion of the plunger and is sent to the high-pressure passage. The pressure chamber is provided between the pressure chamber and the low-pressure passage, opens the pressure chamber and the low-pressure passage when the low-pressure fluid is sucked into the pressure chamber, and pressurizes the low-pressure fluid sucked into the pressure chamber. A first valve that closes between the pressure chamber and the low-pressure passage from the start to the completion of the pressurization of the pressurized fluid to the high-pressure passage; and a first valve disposed in the low-pressure passage upstream of the first valve. A second valve for controlling a flow rate of the low-pressure fluid supplied to the pressure chamber via the first valve.

In the above configuration, the suction of the low-pressure fluid is performed by opening the first valve and operating the second valve when the plunger is lowered, and a predetermined amount of the low-pressure fluid controlled by the second valve is provided by: It is introduced into the pressure chamber via the first valve. When the first valve is closed and the plunger starts to rise, the low-pressure fluid in the pressure chamber is pressurized and sent to the high-pressure passage.

In the above configuration, the low-pressure passage leading to the pressure chamber is provided with two valves, a second valve that controls the suction amount of the low-pressure fluid and a first valve that opens and closes the passage, and the pressure chamber passes through the second valve. And a suction amount control system in which all the low-pressure fluid introduced into the high-pressure passage is pressurized and sent to the high-pressure passage. Therefore, there is no need to open the passage for a certain period of time when the plunger is raised, unlike the conventional pre-stroke control in which the suction amount is controlled and the passage is opened and closed with one valve. That is, the valve may be closed immediately after the end of the suction, and the self-closing problem of the conventional valve body does not occur. Therefore, there is no need to increase the size of the device for preventing self-closing or increase the electric power, and it is possible to easily and reliably control the flow rate of pressure-feeding to the high-pressure passage with a simple configuration.

In the configuration of claim 2, the first valve is a check valve configured to flow the fluid only in the direction from the low-pressure passage to the pressure chamber and to block the flow of the fluid in the opposite direction. . As described above, by using the check valve for opening and closing the passage to the pressure chamber, a desired operation can be easily realized, and the structure can be simplified and the cost can be reduced. Further, there is no problem such as a response delay to a valve closing signal as in the case of using a conventional solenoid valve, and the reliability is high.

According to a third aspect of the present invention, the second valve is an electromagnetic valve that controls a flow rate of a fluid by controlling an opening and closing time of a valve body driven by an electromagnetic coil. The second valve does not receive the fluid pressure in the pressure chamber, so that the use of the solenoid valve does not cause a problem as in the related art, and can be reduced in size.

According to a fourth aspect of the present invention, the second valve may be a throttle valve that controls a flow rate by adjusting an opening degree of a valve body.

According to a fifth aspect of the present invention, there is provided means for eliminating a pressure difference acting on both end faces of the valve body. Thereby, the fluid pressure is prevented from acting on the second valve, and the operability is improved.

According to a sixth aspect of the present invention, the valve opening direction of the valve body is different from the fluid flow direction at the time of valve opening. Accordingly, it is possible to prevent a force in the valve opening direction from acting when the valve body is closed, thereby preventing an operation failure or the like.

In the configuration of claim 7, control means for controlling the energization of the solenoid valve is provided, and the control means controls the energization timing so that the solenoid valve starts opening when the plunger is at the maximum lift position. I do. After energization, the solenoid valve has a response delay before opening the valve.For example, if the energization timing is late, the plunger lift amount differs between cycles, and the pumping amount may not be stable. The above-mentioned problem can be solved by calculating an energization timing corresponding to each rotation speed and energizing the electromagnetic valve so that the electromagnetic valve starts opening when the plunger is at the maximum lift position.

Hereinafter, a first embodiment in which the high-pressure supply pump of the present invention is applied to a common rail injection system of a diesel engine will be described with reference to FIGS. In FIG. 2, the engine E is provided with a plurality of injectors I corresponding to the combustion chambers of the respective cylinders, and these injectors I are connected to a common high-pressure accumulator pipe, a so-called common rail R, for each cylinder. Injection of fuel from the injector I into each combustion chamber of the engine E is controlled by ON / OFF of an injection control solenoid valve B1, and while the solenoid valve B1 is open, fuel in the common rail R is injected by the injector I. It is injected into the engine E. Therefore, it is necessary to continuously accumulate a fuel having a high predetermined pressure corresponding to the fuel injection pressure in the common rail R. For this purpose, the high-pressure supply pump P of the present invention is connected via the supply pipe R1 and the discharge valve B2. You.

This high-pressure supply pump P pressurizes fuel sucked from the fuel tank T via a known low-pressure supply pump P1 to a high pressure, and controls the fuel in the common rail R to a high pressure. The common rail R is provided with a pressure sensor S1 for detecting a common rail pressure, and an electronic control unit ECU serving as control means for controlling the system receives a signal from the pressure sensor S1 in advance according to a load or a rotation speed. The discharge amount of the high-pressure supply pump P is determined so as to have the set optimal value, and a control signal is output to the discharge control device P2. Further, information on the number of revolutions and load is input to the electronic control unit ECU from, for example, the engine speed sensor S2 and the load sensor S3, and the electronic control unit ECU determines the optimum value according to the engine state determined by these signals. The injection timing and injection amount (injection period) are determined and a control signal is output to the injection amount control solenoid valve B1.

Next, the high-pressure supply pump P will be described with reference to FIG. In the figure, a cam chamber 11 is formed in a lower end portion of a pump housing 1, and a cam 13 is arranged in the cam chamber 11 around a cam shaft 12 that rotates at a speed half the engine speed. I have. The cam 13 has an elliptical shape and makes a rising stroke of two degrees per rotation of the cam shaft 12.

シ リ ン ダ A cylinder 2 is mounted above the cam chamber 11 of the pump housing 1, and a plunger 21 is reciprocally and slidably fitted in the cylinder 2. The plunger 21 has a cam roller 22, and the cam roller 22 slides on the cam 13.

In the conventional high-pressure supply pump, a spring for constantly pressing the plunger 21 against the cam 13 is often provided. However, the high-pressure supply pump of the present invention employs a suction amount control method. When the pressure chamber 23 descends to the lowest point, cavitation may occur due to the pressure reduction of the pressure chamber 23 described later. Therefore, in the present invention, no spring is provided, and the reciprocating movement of the plunger 21 is performed by a cam lift by rotation of the cam shaft 12 at the time of pressure feeding, and is performed by the pressure (feed pressure) of low-pressure fuel at the time of suction. Therefore, when the suction amount is small, the plunger 21 moves in the direction of the cam 13 only for the supply of the low-pressure fuel, and the cam roller 22 and the cam 13 are separated.

(4) The space formed by the upper end surface of the plunger 21 and the inner peripheral surface of the cylinder 2 is a pressure chamber 23, and pressurizes the fuel supplied therein by raising the plunger 21. The pressurized fuel is pressure-fed from a discharge hole 24 penetrating the side wall of the cylinder 2 to a common rail R (FIG. 2) as a pressure accumulation pipe via a discharge valve 3 fixed to the side wall of the pump housing 1. The discharge valve 3 has a valve body 31 and a return spring 32 for urging the valve body 31 in a valve closing direction. When the pressurized fuel exceeds a predetermined pressure, the discharge valve 3 opens against the spring force of the return spring 32 to increase the pressure. Discharge is performed to a discharge passage 33 which is a passage.

逆 A check valve 4 serving as a first valve is disposed above the pressure chamber 23 via a stopper 41 so as to close an upper opening thereof. The check valve 4 includes a flow path 43 that vertically passes through the housing 42 and a ball-shaped valve body 44 that opens and closes the flow path 43. The flow path 43 expands downward in the middle to form a conical seat surface 45, and when the valve body 44 held on the stopper 41 moves upward and sits on the seat surface 45, The channel 43 is closed.

ス ト ッ パ The stopper 41 has communication holes 41a and 41b at a plurality of positions on the plate surface. The fuel can flow between the flow passage 43 and the pressure chamber 23 through the communication holes 41a and 41b, and the valve body 44 flows backward from the pressure chamber 23 by the communication hole 41b at the center of the stopper 41. It is designed to be easily affected by the dynamic pressure of the fuel. The stopper 41, the check valve 4, and the cylinder 2 are screwed from above the check valve 4 with the lock adapter 5 having a threaded portion formed on the outer periphery thereof. Be pinched.

A feed passage 52 is formed in the lock adapter 5 to communicate a fuel reservoir 51a formed between the pump housing 1 and the fuel reservoir 51b formed between the housing 42 of the check valve 4 and the fuel reservoir 51a. . Low-pressure fuel is introduced into the feed passage 52 from the introduction pipe 14 provided in the wall of the pump housing 1 via a fuel reservoir 51a, and the fuel flows into the flow passage 46 in the check valve 4 facing the fuel reservoir 51b, which will be described later. The liquid is introduced into the flow path 43 through the flow path in the solenoid valve 6. The flow path from the flow path 43 to the introduction pipe 14 forms a low-pressure flow path.

電磁 Above the check valve 4, a solenoid valve 6 for flow control, which is a second valve, is provided. FIGS. 3A and 3B show details of the solenoid valve 6. The solenoid valve 6 has a housing 61 containing a coil 62, and a valve body 71 fitted and fixed to the lower end thereof. The bolt is fixed to the upper surface of the lock adapter 5 by a flange 63 provided on the outer periphery of the housing 61 (see FIG. 1). At this time, the valve body 71 penetrates the center of the lock adapter 5 and faces the check valve 4.

In FIG. 3A, the valve body 71 holds a needle valve 73 slidably in the up-down direction in a cylinder 72 formed at the center in the axial direction. An annular flow path 74a is formed around the lower end of the needle valve 73, a flow path 74b communicating with the flow path 46 of the check valve 4 is opened on a side surface of the flow path 74a, and a lower surface is formed on the lower surface. A flow path 74c communicating with the flow path 43 of the check valve 4 is open (see FIG. 1). A substantially conical seat surface 75 is formed at the open end of the flow passage 74c, and a substantially conical tip of the needle valve 73 is seated on the seat surface 75 to allow the passage between the flow passages 74a and 74c. It is made to close.

Here, as shown in FIG. 3B, the needle valve 73 has a diameter (φd1) of the sliding portion 73a and a diameter (φd2) of the seat edge portion 73b (the contact edge with the seat surface 75 when the valve is closed). ) Is equal to At this time, since the fuel supplied into the flow path 74a around the needle valve 73 balances the force pushing the needle valve 73 upward and the force pushing the needle valve 73 downward, no hydraulic action force is generated by the feed fuel. In addition, a filter 76 is usually provided in the flow path 74b to prevent a foreign substance from entering between the needle valve 73 and the seat surface 75 to always open the valve. The filter 76 may be made of, for example, a metal mesh and its opening may be smaller than the passage area at the time of the maximum lift when the needle valve 73 is opened. The filter 76 is not limited to the inside of the flow path 74b, and may be installed anywhere in the low-pressure flow path from the fuel tank T to the solenoid valve 6.

3 (b), the angle θ1 formed by the distal end of the needle valve 73 is set to be about 1 ° larger than the angle θ2 formed by the seat surface 75 of the valve body 71. Thereby, the adhesion of the seat edge portion when the valve is closed is improved, and wear can be prevented.

An armature 64 is press-fitted and fixed to the upper end of the needle valve 73, and the armature 64 faces the stator 65 at a constant interval (12) (FIG. 3A). The coil 62 is arranged on the outer periphery of the stator 65, and a spring 67 is arranged in a spring chamber 66 provided inside the stator 65, and urges the armature 64 downward in the drawing.

In the state shown in FIG. 3A in which the coil 62 is not energized, the needle valve 73 integrated with the armature 64 is urged downward by the force of the spring 67, and its distal end is seated on the seat surface 75 of the volve body 71. (The valve is closed), and the flow path 74c serving as a communication path to the pressure chamber 23 (FIG. 1) is closed. As described above, the electromagnetic valve 6 is configured to be closed in a non-energized state, so that there is an effect that the fuel is not pumped when the coil is damaged.

When the armature 64 is attracted by the energization of the coil 62 and moves upward against the spring force of the spring 67, the tip of the needle valve 73 integrated therewith separates from the seat surface 75 (valve open), and the low-pressure flow path And the pressure chamber 23 is opened (FIG. 3B). The lift amount (11) at this time is determined by the distance between the upper end surface 73b of the needle valve and the shim 68 provided opposite thereto. Note that the distance (12) between the armature 64 and the stator 65 is 11 + 0.05 when the valve is closed, and 0.05 when the valve is open.

When the valve is opened, the armature 64 moves upward, and the volume of the spring chamber 66 is reduced accordingly. Therefore, it is necessary to communicate the spring chamber 66 with other parts so that the fuel in the spring chamber 66 can move. . In the present embodiment, the valve bodies 71 and the shim 68 are provided with flow paths 77 and 69 that penetrate the valve body 71 and the shim 68 in the up-down direction, and through a gap formed between the lower surface of the valve body 71 and the upper surface of the check valve 4 ( 1), the spring chamber 66 communicates with the flow path 74c below the needle valve 73. As shown in FIG. 3C, a gap is formed between the upper end of the needle valve 73 and the armature 64 so that a gap is formed between the needle valve 73 and the armature 64. Is communicated through.

This allows the fuel in the spring chamber 66 to move, and at the same time, the spring chamber 66 and the flow path 74c have the same pressure even if the pressure in the flow path 74c increases when the valve is opened. No operation is performed, and malfunction of the needle valve 73 can be prevented.

As a means for communicating the spring chamber 66 with the flow path 74c, a flow path 78 can be provided inside the needle valve 73 as shown in FIGS. 4A and 4B instead of the flow path 77. . At this time, the sliding part 73a of the needle valve 73 has a small diameter at the middle part, opens the flow passage 78 here, and further makes the upper part 73c polygonal, thereby communicating with the space 79 below the shim 68. .

Next, the operation of the high-pressure supply pump P according to the present embodiment will be described with reference to FIGS. FIGS. 5A and 5B show the fuel intake stroke. After the fuel pumping is completed, that is, the plunger 21 moves upward in the cylinder 2 by the rotation of the camshaft 12 and reaches the highest point. Is reached, the flow is started by energizing the flow control solenoid valve 6. When the needle valve 73 is opened by energization, the low-pressure fuel supplied from the low-pressure supply pump P1 (FIG. 2) is supplied to the introduction pipe 14, the fuel reservoir 51a, the feed passage 52, the fuel reservoir 51b, the channels 46, 74b, 74a, 74c sequentially flows into the flow passage 43 in the check valve 4. The check valve 4 is normally open as shown in the figure, and the fuel is introduced into the pressure chamber 23 through the communication hole 41 a of the stopper 41 from the gap between the valve body 44 and the seat surface 45. At this time, the plunger 21 is pushed down by the introduced fuel. This process is called a suction process. In this process, the cam roller 22 and the cam 13 are in sliding contact.

When the energization of the flow control solenoid valve 6 is stopped by a control signal from the electronic control unit ECU of FIG. 2, the needle valve 73 closes to close the flow path to the pressure chamber 23, and the suction ends. FIG. 5 (b)). When the suction is completed, the cam roller 22 and the cam 13 are separated because the plunger 21 is not further pushed down.

6 (a) and 6 (b) are views showing a fuel pressure-feeding process. After the suction is completed, the plunger 21 starts to rise again with the rotation of the cam 13, and at the same time, the valve body 44 of the check valve 4 is moved to the stopper. The fuel flows upward from the communication holes 41a and 41b in the direction of valve 41 to receive the force in the valve closing direction and rises to seat on the seat surface 45 to close the valve. Therefore, the fuel in the pressure chamber 23 is compressed as the plunger 21 moves up to a high pressure. When the pressure exceeds a predetermined pressure, the fuel cell 31 of the discharge valve 3 is pushed open against the urging force of the return spring 32. As a result, all the pressurized fuel is pressure-fed from the discharge valve 3 into the common rail R via the discharge passage 33.

(4) When all of the pressurized fuel in the pressure chamber 23 is discharged from the discharge valve, the pressure feeding ends, and the discharge valve 3 is closed by the return force of the return spring 32 (FIG. 6B). During this pumping stroke, the pressure in the pressure chamber 23 always acts in a direction to close the valve body 44 of the check valve 4, so that the check valve 4 does not open.

In the above configuration, the amount of fuel sucked into the pressure chamber 23 is controlled by the flow control solenoid valve 6, and the check valve 4 is provided in the middle of the flow path to the pressure chamber 23, and the fuel sucked into the pressure chamber 23 is A suction amount control system is adopted in which all the pressure is applied and the pressure is fed to the common rail R. As described above, since the control of the fuel intake amount and the opening / closing of the flow path to the pressure chamber 23 are performed by separate valves, the flow path after the plunger moves to the rising stroke as in the conventional pre-stroke control. It is not necessary to keep the valve open, and the problem of self-closing of the valve element does not occur. The cost can be reduced by using the check valve 4 having a simple structure, and the check valve 4 operates immediately at the start of pressurization without the problem of response delay unlike the solenoid valve, so that reliability is improved. Excellent. Further, since no high pressure is applied to the flow control solenoid valve 6, the force of the return spring 67 may be small, and the coil 62 that generates the attraction force may be small, so that the size can be reduced. However, with the above configuration, it is possible to easily and reliably control the flow rate of the pressure-feeding to the high-pressure passage with a simple configuration, and it is not necessary to increase the size of the device or increase the power.

In the first embodiment, the valve body 44 of the check valve 4 is a ball valve. However, the shape of the valve body is not limited to this. Any shape may be used as long as the road 43 can be closed. Further, although the valve element 44 of the check valve 4 is configured to be opened by its own weight, it may be configured to be closed by its own weight. In this case, the valve is opened by the fuel pressure only when the fuel is introduced into the pressure chamber 23, and there is an advantage that the valve is surely closed from the start to the end of the pressure feeding.

FIGS. 7 to 10 show a second embodiment of the present invention. FIG. 7 is a system diagram. In the present embodiment, the high-pressure supply pump P has a configuration in which the feed pump P1 shown in FIG. 2 is built in, and the low-pressure fuel pumped up from the fuel tank T by the feed pump P1. To a high pressure to control the fuel in the common rail R to a high pressure. The electronic control unit ECU that controls the system outputs a control signal to the discharge control device P2 such that the signal from the pressure sensor S1 has a preset value. The electronic control unit ECU further includes an engine speed sensor S2 (detects a missing tooth signal (NE pulse) as shown in FIG. 11 described later from a coupling K connected to a cam shaft), TDC (top dead center). ) Information about the number of revolutions, the position of the TDC, the accelerator opening, and the temperature is input by the sensor S4, the throttle sensor S5, and the temperature sensor S6, and the electronic control unit ECU performs injection according to the engine state determined by these signals. A control signal is output to the quantity control solenoid valve B1.

Next, the details of the high-pressure supply pump P will be described with reference to FIGS. In the figure, a drive shaft D is rotatably supported in a pump housing 1 via bearings D1 and D2. The drive shaft D sucks fuel from a fuel tank T (FIG. 7) and feeds the fuel to a feed passage 15. Is connected to a vane type feed pump P1 for supplying pressure to the pump. At the right end of the drive shaft D, a cam 13 is integrally formed, and the cam 13 rotates together with the drive shaft D at half the speed of the engine. When the cam 13 rotates, the rotor P12 of the feed pump P1 rotates via the half-moon plate P11, and the rotation causes fuel from the fuel tank T to pass through a passage (not shown) from the inlet valve B3 into the feed pump P1. It is introduced into a space (a space surrounded by the rotor P12, the casing P13, and the covers P14, 15). The introduced fuel is pressure-fed to a feed passage 15 via a passage (not shown) by a vane P16 disposed on the rotor P12 as the rotor P12 rotates.

(4) The fuel in the feed passage 15 is used not only for pressure feeding to the common rail as described below, but also flows into the pump from the squeezing S and is used for lubrication inside the pump. The lubricated fuel exits the valve V and is returned to the fuel tank. Further, the pressure inside the pump is adjusted by the valve V so as to be almost the atmospheric pressure.

ヘ ッ ド A head H is fitted into the right end opening of the pump housing 1, and the head H is inserted into the cam 13 with its left end center portion protruding. A plurality of sliding holes 2a are provided in the center of the left end of the head H (FIG. 9), and a plunger 21 is supported in each of the plurality of sliding holes 2a so as to be reciprocable and slidable. I have. Here, the sliding hole 2a corresponds to the cylinder 2 in the first embodiment. A shoe 21a is provided at an outer end of each plunger 21, and a cam roller 22 is rotatably held by each shoe 21a.

The cam 13 is disposed so as to be in sliding contact with the outer periphery of the cam roller 22, and a cam surface 13a having a plurality of cam ridges arranged at equal intervals is formed on the inner peripheral surface of the cam 13. . The space formed between the inner end surface of each plunger 21 and the inner wall surface of each sliding hole 2a is a pressure chamber 23. Thus, when the cam 13 integrated with the drive shaft D rotates, the plunger 21 reciprocates in the sliding hole 2 a and pressurizes the fuel in the pressure chamber 23. FIG. 9 shows a state where the plunger 21 is at the highest point.

に お い て In FIG. 8, a lock adapter 5 is attached to the right end of the head H via a stopper 41 and a check valve 4. A fuel reservoir 53 is formed between the lock adapter 5 and the pump housing 1. A solenoid valve 6 for controlling the amount of fuel flowing into the pressure chamber 23 is provided at the right end of the lock adapter 5. When the solenoid valve 6 is opened, the fuel pool 53 through the feed passage 15, The fluid flows into the pressure chamber 23 through the passage 54, the seat surface 75 of the solenoid valve 6, the seat surface 45 of the check valve 4, the passage 41c in the stopper 41, and the passage 23a in the head H. The solenoid valve 6 and the check valve 4 constitute the discharge control device P2 in FIG.

The check valve 4 has a flow path 43 that penetrates the housing 42 in the left-right direction, and a valve body 44 that opens and closes the flow path 43. The flow path 43 expands in the direction of the pressure chamber 23 (leftward in the figure) on the way to form a conical seat surface 45, and the valve body 44 is moved rightward by a spring 47 held in the stopper 41. And is seated on the seat surface 45. As described above, the check valve 4 is closed in the illustrated normal state, and when the solenoid valve 6 is opened and fuel flows in, the valve body 44 is opened by the pressure of the fuel. . The valve body 44 has a groove 44a on the outer periphery as shown in FIG. 10B, and the fuel flows through the groove 44a.

The configuration and operation of the electromagnetic valve 6 and the discharge valve 3 for discharging pressurized fuel are the same as those of the first embodiment, and the main components are indicated by the same reference numerals in the figure.

In the above configuration, the high-pressure supply pump P is configured to perform a suction and pressure-feeding process four times per one rotation of the cam 13, and this pressure-feeding amount is determined by the amount of fuel sucked into the pressure chamber 23, that is, the electromagnetic valve 6. Can be controlled by controlling the valve opening angle (or time). Then, while the solenoid valve 6 is open, the check valve 4 is opened by the fuel feed pressure, the plunger 21 is lowered (moves in the radial direction), and fuel is sucked into the pressure chamber 23. During the suction, the cam roller 22 and the cam 13 are in sliding contact with each other. When the suction is completed, the movement of the plunger 21 in the radial direction is stopped, and the cam roller 22 and the cam 13 are separated. The fuel in the pressure chamber 23 is pressurized by raising the plunger 21 (moving in the radial center direction), and the pressurized fuel is sent to the common rail R via the discharge valve 3 fixed to the side wall of the head H. . As described above, also with the high-pressure supply pump P having the above-described configuration, the control of the pumping amount is easily performed by the electromagnetic valve 6 and the check valve 4 for controlling the flow rate, as in the first embodiment.

Next, a control method of the high-pressure supply pump P having the above configuration will be described with reference to FIG. The engine speed sensor S2 in FIG. 7 can detect a missing tooth signal (NE pulse) as shown in FIG. 11 from the coupling K connected to the cam 13 shaft of the pump P, and detects the position of the missing tooth. And the position of the vertex of the cam 13 is at a predetermined angle. The electronic control unit ECU calculates the angle (or time) from which the power is supplied based on the missing tooth signal, and controls the power supply start timing of the electromagnetic valve 6.

FIG. 11 shows the state of the needle valve 73, the lift of the plunger 21, the opening and closing of the valve body 44 of the check valve 4, and the pressure of the common rail R when the optimal control is performed. Normally, a certain period of time T1, T2 is required from when power is supplied to the electromagnetic valve 6 to when the needle valve 73 of the electromagnetic valve starts to open and when the opening is completed. This time is grasped in advance (or may be constantly detected by a lift sensor or the like), and the energization timing is adjusted according to the rotation speed such that the valve opening start timing is exactly at the top of the cam 13. .

In this way, the suction is started simultaneously with the start of the suction stroke, and the plunger 21 is lowered (moves in the radial direction) by an angle (or time) θ obtained by subtracting the valve opening start time from the energizing period of the solenoid valve 6. Then, the fuel supplied to the pressure chamber 23 is pressurized with the rise of the plunger 21 (movement toward the center of the radius) in the pressure feeding process of the next cycle, and is fed to the common rail R by pressure. In this pumping step, the check valve 4 is pressurized, so that the valve body 44 does not open. Therefore, the suction amount becomes the pressure feeding amount, and the control of the common rail pressure can be easily performed.

(4) The suction amount is controlled by the power supply period of the solenoid valve 6, and the longer the power supply period, the larger the suction amount, and the shorter the power supply period, the smaller the suction amount. The dotted line in the figure indicates a case where the intake amount is large, and the plunger 21 descends to the lowest point to suck and pump the maximum amount of fuel. The solid line indicates the case where the suction amount is small, the plunger 21 only descends to a position corresponding to the suction amount, and the pumping amount is small. When the amount of suction is small, the cam roller 22 and the cam 13 are in sliding contact with each other when the plunger 21 starts to descend. However, when the solenoid valve 6 is closed, the plunger 21 stops descending. Leave.

FIG. 12 shows a pumping amount characteristic when such control is performed. Here, the angle obtained by subtracting the valve opening start time T1 from the energizing period at a certain pump speed is defined as θ. As the angle θ increases, the pumping amount monotonously increases, and it can be seen that the pumping amount (suction amount) can be controlled based on this.

FIG. 13 shows a case where the energization timing of the solenoid valve 6 is late. For example, when the energization start timing is set to the top of the cam 13, the needle valve 73 of the solenoid valve 6 is opened after passing the top of the cam 13. Become. Then, at the start of suction (when the plunger 21 is lowered), the cam 13 and the cam roller 22 are separated, and the feed pressure of combustion usually pulsates and is not constant. It differs between the cycles, and there is a possibility that the pumping amount is not stabilized (shown by a in the figure). Further, if the pumping amount is not stable, the fluctuation of the common rail R pressure (indicated by b in the drawing) may be large.

FIG. 14 shows a case where the energization time to the solenoid valve 6 is early. In the pump P having the above configuration, when the suction amount is small, the descending amount of the plunger 21 is also small, so that the cam 13 and the cam roller 22 are separated until the next stroke. If the energization time is too early, the needle valve 73 opens in the first half of the pressure feeding stroke, and the fuel pushes and opens the valve body 44 of the check valve 4, and the fuel is illegally drawn into the pressure chamber 23. . For this reason, there is a possibility that control when the pumping amount is small is difficult.

Accordingly, as shown in FIG. 11, when the cam lift starts to descend, the needle valve 73 is opened, and the energizing timing is controlled so that the cam 13 and the cam roller 22 descend while sliding while inhaling. By doing so, it is possible to improve the controllability of the suction amount, that is, the pumping amount.

FIG. 15 is a flowchart showing an example of control by the electronic control unit ECU. As shown in the system diagram of FIG. 7, various information is constantly input from the sensors to the electronic control unit ECU, and the electronic control unit ECU receives the engine (NE) signal from the NE signal detected by the engine speed sensor S2. The pump) rotation speed is calculated based on the accelerator opening detected by the throttle sensor S5 and a target common rail pressure (CPTRG) and an injection amount (a pumping amount) based on a previously input control map (steps 1 and 2). . Subsequently, the power supply start timing and power supply period (angle or time or both) of the solenoid valve 6 according to the pump rotation speed and the pumping amount are calculated (step 3), and power is supplied to the solenoid valve 6.

Further, the electronic control unit ECU always detects the common rail R pressure (CPTRT) by the pressure sensor S1, and compares the detected common rail R pressure (CPTRT) with the target common rail pressure (CPTRG). (Step 4) If different, correction is made. As a correction method, (CPTRT-CPTRG) is calculated to calculate a necessary increase in the amount of pumping (step 5), and is changed to an energization period (valve opening angle) corresponding to the increase (step 6). Next, it is determined again whether or not (CPTRT = CPTRG) (step 7). If not (CPTRT = CPTRG), the process returns to step 5 to repeatedly perform feedback control until (CPTRT = CPTRG).

Here, the control method has been described in the configuration of the second embodiment, but the control method may be applied to the configuration of the first embodiment.

In each of the above embodiments, the flow control electromagnetic valve 6 is used as the second valve. Instead, a throttle valve 8 having a variable throttle mechanism shown in FIG. 16 as the third embodiment is used. You can also. In the figure, the throttle valve 8 has a valve body 81 that penetrates the housing up and down, and the valve body 81 has a conical tip extending into the flow path 43 of the check valve 4 to close it. . The valve opening of the valve body 81 is changed by changing the lift amount thereof by a variable throttle mechanism 82, and the opening area of the flow path 43 is changed so that the low-pressure fluid sucked into the pressure chamber 23 from the low-pressure passage 25. Amount can be adjusted.

In each of the above embodiments, the check valve 4 is used as the first valve. However, the present invention is not limited to this. The valve opens at least when the low-pressure fluid is sucked into the pressure chamber 23 and is sucked into the pressure chamber 23. The valve may be configured to be closed from the start of pressurization of the low-pressure fluid to the end of pumping.

That is, in each of the above embodiments, the check valve 4 is used as the first valve, the valve is opened by the fluid flowing into the pressure chamber 23, and the valve is closed by the pressure of the pressure chamber 23 which rises when the plunger 21 rises. are doing. However, the first valve is provided with a pressurizing predicting unit (for example, a pressure sensor as a pressure detecting unit provided in the pressure chamber, The output from the pressurization predicting means (each sensor) is input using a crank angle sensor for detecting the pressure, and a position sensor as a plunger rise detecting means for detecting the rise of the plunger 21, so that the pressurizing is predicted. An electromagnetic valve that closes (from the start of the prediction of pressurization to the end of pressure feeding) may be used.

In the above-described first embodiment, an example of a high-pressure supply pump using the row fuel injection system as the base and the second embodiment as an inner cam pressure-feeding type base is shown. Of course, the present invention may be applied to the fuel injection system.

1 is an overall sectional view of a high-pressure supply pump according to a first embodiment of the present invention. 1 is an overall configuration diagram of a fuel injection system including a high-pressure supply pump according to a first embodiment. (A) is an overall cross-sectional view showing a state when the flow control solenoid valve used in the first embodiment is closed, and (b) is an overall cross-sectional view showing the flow control solenoid valve when opened. (C) is a sectional view taken along line AA of (b). (A) is the whole sectional view which shows other forms of the solenoid valve for flow control, (b) is the B section enlarged view of (a). It is a figure which shows operation | movement of the high pressure supply pump of 1st Embodiment, (a) is the whole sectional drawing of the high pressure supply pump which shows the state at the time of completion | finish of suction while (a) is inhaling. It is a figure which shows the operation | movement of the high pressure supply pump of 1st Embodiment, (a) is the whole sectional view of the high pressure supply pump which shows the state at the time of a pressure feed, and the state at the time of a pressure feed completion. FIG. 4 is an overall configuration diagram of a fuel injection system including a high-pressure supply pump according to a second embodiment of the present invention. It is the whole high pressure supply pump sectional view of a 2nd embodiment. FIG. 9 is a sectional view taken along line CC of FIG. 8. FIG. 9 is a partially enlarged sectional view of FIG. 8. It is a figure showing the optimal control method of the amount of pumping of the high pressure supply pump of a 2nd embodiment. It is a figure showing the amount amount of pumping when optimal control is performed. It is a figure for explaining the amount characteristic of pumping when the energization time to a solenoid valve is late. It is a figure for explaining the amount characteristic of pumping when an energization time to a solenoid valve is early. It is a flowchart which shows the control method of the high pressure supply pump of 2nd Embodiment. It is a partial sectional view of a high pressure supply pump showing a 3rd embodiment of the present invention. It is a partial sectional view of the conventional high pressure supply pump.

Explanation of reference numerals

P High-pressure supply pump 1 Pump housing 11 Cam chamber 12 Cam shaft 13 Cam 2 Cylinder 21 Plunger 22 Cam roller 23 Pressure chamber 24 Discharge hole 3 Discharge valve 31 Valve 32 Return spring 33 Discharge passage (high pressure passage)
4 Check valve (first valve)
41 Stopper 41a, 41b Communication hole 42 Housing 43 Flow path (low pressure passage)
44 Valve body 45 Seat surface 46 Flow path (low pressure passage)
5 Lock adapter 51a, 51b Fuel pool (low pressure passage)
52 Feed passage (low pressure passage)
6 Flow control solenoid valve (second valve)

Claims (7)

A plunger is inserted and disposed in the cylinder so as to be able to reciprocate, a pressure chamber is formed by the inner wall surface of the cylinder and the end face of the plunger, and a low-pressure fluid introduced from a low-pressure passage into the pressure chamber is supplied to the plunger. A high-pressure supply pump pressurized by the reciprocating motion of the high-pressure supply pump and provided to the high-pressure passage. The high-pressure supply pump is provided between the pressure chamber and the low-pressure passage. A first valve that opens between the passages and closes between the pressure chamber and the low-pressure passage from the start of pressurization of the low-pressure fluid sucked into the pressure chamber to the end of the pressurization of the pressurized fluid to the high-pressure passage; And a second valve disposed in the low-pressure passage upstream of the first valve and controlling a flow rate of a low-pressure fluid supplied to the pressure chamber via the first valve. And high pressure supply pump. 2. The high-pressure supply according to claim 1, wherein the first valve is a check valve configured to flow a fluid only in a direction from the low-pressure passage toward the pressure chamber and to block a flow of the fluid in a reverse direction. pump. 3. The high-pressure supply pump according to claim 1, wherein the second valve is an electromagnetic valve that controls a flow rate of a fluid by controlling an opening / closing time of a valve body driven by an electromagnetic coil. 3. The high-pressure supply pump according to claim 1, wherein the second valve is a throttle valve that controls a flow rate by adjusting an opening degree of a valve body. 4. A high-pressure supply pump according to claim 3, further comprising means for eliminating a pressure difference acting on both end faces of said valve element. The high-pressure supply pump according to any one of claims 3 to 5, wherein a valve opening direction of the valve body and a fluid flow direction at the time of valve opening are made different. 4. The control device according to claim 3, further comprising control means for controlling energization of the solenoid valve, wherein the control means controls the energization timing so that the solenoid valve starts opening when the plunger is at the maximum lift position. High pressure feed pump.