JPS63170553A - Distributor type fuel injection pump - Google Patents

Abstract

PURPOSE:To simplify and ensure the control of the fuel delivery rate by changing the pressurizing force of the first and the second pressure chamber through forming the first pressure release port in the first cylinder for communicating the release port with a plunger reciprocated by a cam. CONSTITUTION:A plunger 9 is inserted slidably into a first cylinder 8 and further a second cylinder 18 is equipped therein. A pressurizing feed piston 22 is inserted slidably into the second cylinder 18. A first pressure chamber 24 is formed among a plunger 9, the first and the second cylinder 8, 18, and a second pressure chamber 26 is formed by the second cylinder 18, a body 20 and the bottom of the pressurizing feed piston 22. A pressure release port 28 is provided on the first cylinder 8 and the port 28 is opened and closed by reciprocating motion of the first pressure chamber 24 and the plunger 9. The plunger 9 is reciprocated by a cam device 10 together with a driving shaft 3 synchronized with the rotation of the first cylinder 8, therefore pressure in the first and the second pressure chamber 24, 26 is made in two stage, high and low, by displacement of the pressurizing feed piston 22, thereby fuel delivery rate can be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a fuel injection pump used in a compression single-ignition engine, and particularly to a distribution type fuel injection pump having a two-stage oil feed rate mechanism.

(Prior Art) In a compression single ignition type engine, it is desirable to have a two-stage injection rate characteristic in which the injection rate is first lowered and then the injection rate is increased in order to achieve smooth combustion. Further, it is desirable that the injection rate can be changed depending on the operating state of the engine. For example, during idling, the injection rate should be lowered to reduce combustion noise, and during high-speed operation, the injection rate should be increased to increase output.

Controlling the oil feed rate of a distribution type fuel injection pump in order to obtain such injection rate characteristics is described in, for example, Japanese Patent Application Laid-Open No. 59-907.
It is known from the publication No. 62. This has a plunger divided into a small-diameter plunger and a large-diameter plunger, and the fuel is first pumped from the first pressure chamber pressurized by the small-diameter plunger, and then the fuel is pumped from the first pressure chamber pressurized by the large-diameter plunger. Fuel is also forced to be fed from the second pressure chamber to obtain a two-stage oil feed rate characteristic. The first pressure chamber and the second pressure chamber each have a reflux passage communicating with the pump chamber, and by operating a solenoid valve provided in this reflux passage, it is possible to change the timing of the start of pressure pumping and the timing from a low oil delivery rate to a high oil delivery rate. It is designed to control when to change the oil feed rate. That is, by closing the first electromagnetic valve, pressure feeding of fuel is started from the first pressure chamber, and then by closing the second electromagnetic valve, pressure feeding of fuel from the second pressure chamber is started, The oil feeding rate can be controlled by the timing of closing this second solenoid valve.

(Problems to be Solved by the Invention) However, in the above conventional example, the oil feed rate is controlled by a solenoid valve, which requires a high-speed response for opening and closing, which is difficult to realize. There was a problem.

Therefore, this invention solves the above-mentioned conventional problems, and
The object of the present invention is to provide a distribution type fuel injection pump having a simpler two-stage oil feed rate mechanism.

(Means for solving the problem) However, the distribution type fuel injection pump according to the present invention has the following features:
a pump body constituting a pump chamber in which fuel is stored; a drive shaft rotatably supported by the pump body; and a drive shaft slidably fitted into a barrel portion provided on the pump body;
a first cylinder that rotates in synchronization with the drive shaft; a plunger that is slidably inserted into the first cylinder;
cam means for converting rotation of the drive shaft into reciprocating rotational motion of the plunger; and a timer connected to the cam means;
the first cylinder has a smaller inner diameter than the first cylinder;
a second cylinder fitted into the cylinder and fixed to the pump body; a pressure-feeding piston slidably fitted into the second cylinder and having one end abutting the plunger; a control sleeve fitted onto a portion of the cylinder facing the pump chamber; a first driving means for driving the first cylinder in the axial direction; and a second driving means for driving the control sleeve in the circumferential direction. and.

A first pressure chamber is configured by being surrounded by the first cylinder, the plunger, the second cylinder, and the pressure-feeding piston, and the plunger connects the first pressure chamber and the pump chamber with each other. A first pressure relief boat communicates with the first pressure relief boat until it is displaced by a predetermined stroke from the point.
a suction passage formed in a cylinder and surrounded by the second cylinder and the pressure-feeding piston to constitute a second pressure chamber, which communicates the second pressure chamber with the pump chamber during the suction stroke of the plunger; , the pump body includes a distribution and discharge passage that communicates the second pressure chamber with a discharge portion provided in the pump body during a discharge stroke of the plunger;
a second pressure relief boat formed in the first cylinder and the second cylinder, further connected to the distribution and discharge passage, and whose timing of communication with the pump chamber is changed depending on the circumferential position of the control sleeve; is formed in the first cylinder.

(Operation) Therefore, when the drive shaft rotates, the first cylinder rotates and the plunger reciprocates. For this reason. When the plunger starts moving forward from the bottom dead center, the first pressure chamber initially communicates with the pump chamber via the first pressure relief boat, so the fuel in the first pressure chamber escapes to the pump chamber side. ．． The plunger pushes the pressure-feeding piston, and the pressure-feeding piston advances at the same speed as the plunger, pressurizing the second pressure chamber slowly, and fuel is pumped at a low oil feed rate.

A first cylinder is then formed in the first cylinder by the plunger.
When the pressure relief boat is shut off, fuel is trapped in the first pressure chamber, and the pressure in this first pressure chamber is increased by the plunger. Therefore, in order to keep the volume of the first pressure chamber constant, the pressure-feeding piston is separated from the plunger and the first pressure chamber is moved away from the plunger.
It is moved by the pressure in the pressure chamber. At this time, the first pressure chamber is pressurized by the large-diameter plunger, and the pressure drives the small-diameter pressure-feeding piston, so that the pressure-feeding piston is... It has a speed that is inversely proportional to the cross-sectional area ratio of the plunger and the pumping piston. Therefore, the second pressure chamber is rapidly pressurized, and fuel is pumped at a high oil delivery rate.

A second pressure relief boat, which was closed off by the control sleeve, then opens into the pump chamber, and the fuel in the second pressure chamber is returned to the pump chamber via this second pressure relief boat, causing the second pressure The pressure of the fuel in the chamber drops rapidly and pressure feeding ends.

When the first cylinder is moved in the axial direction by the first driving means, the position of the first pressure relief boat formed in the first cylinder relative to the plunger changes, so that the oil delivery rate changes from a low oil delivery rate to a high oil delivery rate. The timing of the transition changes and the oil feeding rate can be changed, so that the above-mentioned problems can be achieved.

(Example) In Fig. 1, the distribution type fuel injection pump has pump chamber 2
A drive shaft 3 that receives drive torque from an engine is rotatably inserted into the pump body 1. A vane pump 4 is provided on the drive shaft 3, and the vane pump 4 sucks fuel from a fuel port 5 formed in the pump body 1, pressurizes it with the vane pump 4, and sends it into the pump chamber 4 where it is stored. The pressure of the fuel in the pump chamber 4 is adjusted by a regulating valve 6 provided on the discharge side of the vane pump 4 so as to correspond to the engine speed.

A barrel portion 7 is fixed to the pump body 1 described above, and a first cylinder 8 is slidably fitted into the barrel portion 7. Further, a plunger 9 is slidably inserted into one end of the first cylinder 8. The first cylinder 8 and plunger 9 are connected to the drive shaft 5 by a cam means 10, which will be described below.

The cam means 10 includes a cam disk 11, a coupling 12 that reciprocally connects the cam disk 11 to the drive shaft 5, a roller 13 formed around the end surface of the cam disk 11 and against which a cam comes into contact, and this roller. 13 and a roller holder 14 for receiving the roller holder 13. cam disc 11
A connecting pin 14 is formed on the periphery of the end surface on the side opposite to the drive shaft, and an engagement groove 16 formed on the periphery of the end surface of the first cylinder 8 engages with this connecting protrusion 15 to allow movement in the axial direction. There is. Also, a plunger 9 is provided at the center of this cam disc 11.
is fixed. Therefore, when the drive shaft 5 rotates, the cam disk 11 rotates via the coupling 12, and the first cylinder 8 only rotates in synchronization with the rotation of the drive shaft 5. The plunger 9 reciprocates while rotating along the cam of the cam disk 11.

As is well known, the timer 17 has a timer piston that is displaced in accordance with the pressure of fuel in the pump chamber 2 that is related to the engine speed, and this timer piston is connected to the roller holder 14.
The roller holder 14 is rotated according to the engine speed, and the drive shaft 5, the cam disc 11, and the first
The phase of the cylinder 8 and plunger 9 is adjusted. Note that, in addition to the timer shown in this embodiment, a well-known electronically controlled timer can be used as the timer 17.

The second cylinder 18 is fixed to the pump body 1 by being sandwiched between the barrel portion 7 of the pump 1 and the plug 19 screwed to the pump body 1, with a flange formed at one end thereof, and a second cylinder 18 having a flange formed at one end thereof. The side is inserted into the first cylinder 8. The tip surface of the first cylinder 8 and the second cylinder 18 constitute a pressure equalization chamber 20, and this pressure equalization chamber 20 communicates with the pump chamber 2 through a pressure equalization hole 21 formed in the barrel portion 7. , the pressure in the pressure equalization chamber 20 is made the same as that in the pump chamber 2,
The first cylinder 8 is allowed to move in the axial direction.

The pressure-feeding piston 22 is slidably inserted into the second cylinder 18 , and one end of the pressure-feeding piston 22 in which the pressure receiving groove 23 is formed is in contact with the tip of the plunger 9 . This pressure-feeding piston 22, the above-mentioned first cylinder 81. A first pressure chamber 2 surrounded by a plunger 9 and a second cylinder 18
4 are configured. This first pressure chamber 24 includes a first
A return spring 25 is housed in the second cylinder 18 to press the plunger 9. Further, a second pressure chamber 26 is surrounded by the second cylinder 18, the plug 19, and the pressure-feeding piston 22.

A second return spring 27 is provided in the second pressure chamber 26.
is housed in such a way that the plug 19 presses the pressure-feeding piston 22.

The first pressure chamber 24 is... The plunger 9 communicates with the pump chamber 2 via a first pressure relief boat 28 formed in the first cylinder 8 until the plunger 9 reaches a predetermined stroke from the bottom dead center.

Further, a communication passage 29 that communicates this first pressure chamber 24 and the pump chamber 2 is formed in the plunger 9, and this communication passage 29
is provided with a check valve 30 that prevents backflow from the first pressure chamber 24 to the pump chamber 2. This check valve 30
is caused by fuel leaking from the first pressure chamber 24. This is to prevent the first pressure chamber 24 from becoming a negative pressure and generating bubbles when the plunger 9 returns.

The second pressure chamber 26 communicates with the pump chamber 2 via a suction passage 31 for sucking fuel from the pump chamber 2 during a suction stroke in which the pressure-feeding piston 22 retreats. This suction passage 31
consists of suction holes 32 formed in the pump body 1 and suction boats 33 formed in the first cylinder 8 in a number corresponding to the number of cylinders, and when the pressure piston 22 enters the suction stroke to retreat, the The suction port 33 of the first cylinder 8 communicates with the suction hole 32, and the fuel reservoir chamber 34 is surrounded by the first cylinder 8 and the second cylinder 1, and the fuel is formed in the second cylinder 18. Fuel is sucked into the second pressure chamber 26 through the suction/discharge hole 35 . The pump body l is provided with a solenoid valve 36 for closing the suction hole 32 when the engine is stopped.

Further, this second pressure chamber 26 is connected to a discharge portion 37 provided in the pump body 1 via a distribution/discharge passage 38 for discharging from the second pressure chamber 26 during a discharge stroke in which the pressure-feeding piston 22 advances. Communicate. The discharge portions 37 are provided in a number corresponding to the number of cylinders, and are composed of a discharge joint in which a discharge hole 39 is formed, and a delivery valve 40 is disposed therein. The distribution/discharge passage 38 is formed in the axial direction of the first cylinder 8 and has one end connected to the aforementioned fuel reservoir chamber 34.
1. A distribution port 42 is formed around the first cylinder 8 to connect the vertical hole 41, and a number of distribution ports 42 corresponding to the number of cylinders are formed in the pump body 1 to communicate the distribution port 42 with the discharge part 37. The distribution port 42 and the distribution hole 43 communicate with each other during the discharge stroke in which the pressure-feeding piston 22 moves forward.

A circumferential groove 44 is formed near the base of the first cylinder 8 described above, and a first retaining pin 45 is engaged with this circumferential groove 44 . This first retaining pin 45 is connected to the first connecting rod 4
6 to the first electromagnetic actuator 47;
The first electromagnetic actuator 47
The cylinder 8 is adapted to be displaced in the axial direction.

Further, a control sleeve 48 is slidably fitted onto a portion of the first cylinder 8 facing the pump chamber 2 .

This control sleeve 48 has a second engagement pin 4.
9 is engaged, and this second engagement pin 49 is connected to the second connecting rod 5.
0 to the 20th electromagnetic actuator 51,
A pressing force in the axial direction is received from this 2' electromagnetic actuator 51. However, a diagonal groove 52 cut diagonally is formed in the peripheral edge of the control sleeve 48 , and a third engagement pin 53 engages with this diagonal groove 52 , and this engagement pin 53 extends from the roller holder 14 . It is fixed to the third connecting rod 54 which is attached to the third connecting rod 54. Therefore, when this control sleeve 48 receives an axial force from the second electromagnetic actuator 51, it rotates while moving in the axial direction, and is also rotated by the roller holder 14. Furthermore, this control sleeve 4
A number of cut-off grooves 55 corresponding to the number of cylinders are formed on the inner surface of the cylinder 8. Opposing this cut-off groove 55,
A second pressure relief boat 56 connected to the vertical hole 41 is formed in the first cylinder 8, and this cutoff groove 55 and the second pressure relief boat 56 communicate with each other to form a pressure feeding path. It is as it should be.

Then, the first electromagnetic actuator 47 and the second electromagnetic actuator described above are connected.
The electromagnetic actuator 51 is connected to a control unit (not shown) and is controlled according to operating conditions such as engine speed, load, combustion temperature, etc.

Next, the operation of the above distribution type fuel injection pump will be explained with reference to FIG.

When the drive shaft 3 rotates, the first cylinder 8 rotates via the cam means 10. The plunger 9 rotates back and forth. When the plunger 9 starts moving forward, the first pressure chamber 24 is at a low pressure because it communicates with the pump chamber 2 via the first pressure relief boat 28, and the pressure in the first pressure chamber 24 is low.
is pushed by plunger 9 and starts moving forward. At this time, since the suction port 33 is separated from the suction hole 32 and the second pressure relief boat 56 is separated from the cutoff groove 55 of the control sleeve 48, communication between the pump chamber 2 and the second pressure chamber 26 is prevented. Also, distribution port 4
2 and the distribution hole 43 are aligned, so that the pumping piston 2
2 advances, the fuel confined in the second pressure chamber 26 is pressurized, pushes open the delivery valve 40, and is discharged from the discharge hole 39.

At this time, pressure feeding begins, and is shown as θ in FIG. Until the first pressure relief boat 28 is closed by the plunger 9, the pump piston 22 moves forward at the same speed as the plunger 9, so the oil delivery rate is low.

When the plunger 9 further moves forward and closes the first pressure relief boat 28 (at θ2 in FIG. 2), the first pressure chamber 24
of fuel is trapped, and this first pressure chamber 24 becomes high pressure. Therefore, the pressure-feeding piston 22 moves forward away from the plunger 9 so as to keep the volume of the first pressure chamber 24 constant. In this case, the pressure piston 22. Since the plunger 9 moves forward with pressure that pressurizes the first pressure chamber 24. The speed becomes inversely proportional to the cross-sectional area ratio with the plunger 9, and the oil feeding rate increases rapidly.

Further, the plunger 9 moves forward and the second pressure relief boat 56 reaches the cutoff of the control sleeve 48 +115.
5 (at θ3 in FIG. 2), the second pressure chamber 26
communicates with the pump chamber 2 through the vertical hole 41 of the first cylinder 8, the fuel in the second pressure chamber 26 escapes to the pump chamber 2, the pressure in the second pressure chamber 26 decreases rapidly, and the fuel is discharged. The valve 40 closes and becomes a pressure feed path.

Next, when the plunger 9 and the pressure-feeding piston 22 are retracted by the first return spring 25 and the second return spring 27, the suction boat 33 and the suction hole 32 are aligned, and the second Fuel is sucked into the pressure chamber 26 of. The volume of the first pressure chamber 24 is approximately constant. During pressurization by the plunger 9, some fuel leaks from between the first cylinder 8 and the plunger 9 into the pump chamber 2, and the check valve 30 opens to compensate for the fuel, and the communication passage 29
Fuel is supplied to the first pressure chamber 24 via. Therefore, there is no possibility that the first pressure chamber 24 becomes negative pressure, and the generation of bubbles can be prevented.

Activation of the first electromagnetic actuator 47, which is controlled by the operating state of the engine, moves the first cylinder 8 in the axial direction and changes the position of the first pressure relief boat 28 relative to the plunger 9.

For this reason, as shown by the dashed line in FIG. 2, the conversion point from a low oil feed rate to a high oil feed rate is adjusted, and as a result, the oil feed rate is controlled.

Furthermore, when the second electromagnetic actuator 51, which is controlled by the operating state of the engine, is activated, the diagonal groove 52 of the control sleeve 48 engages with the third engagement pin 53, so that the control sleeve 48 moves in the axial direction. It rotates while being moved. Therefore, the position of the second pressure relief boat 28 in the cutoff groove 55 is changed, the timing of the pressure feeding passage is adjusted, and the injection amount is controlled.

Further, when the timer 17 controlled by the pressure of the fuel in the pump chamber 2 is activated, the roller holder 14 connected to the timer 17 is activated.
rotates, the relative position of the cam disk 11 in the circumferential direction with respect to the drive shaft 3 is shifted, and the phase of the reciprocating motion of the plunger 9 based on the rotation of the drive shaft 3 is adjusted, thereby controlling the injection timing. In this case, since the roller holder 14 and the control sleeve 48 are connected via the third connecting rod 54, the injection amount does not change. That is, if the roller holder 14 and the control sleeve 48 are not connected, the position of the second pressure relief boat 56 relative to the cutoff groove 55 will shift, the timing of the pressure feeding path will change, and the injection amount will change. You end up doing it. Therefore, even if the control sleeve 48 is rotated in response to a change in the rotational phase of the first cylinder 44 and the timer is activated, the timing of the pressure feeding path remains constant.

(Effects of the Invention) As described above, according to the present invention, the mechanical pressing force of the plunger displaces the pressure-feeding piston until the plunger closes the first pressure relief boat formed in the first cylinder. After closing the first pressure relief boat, the pressure in the first pressure chamber pressurized by the plunger displaces the pressure piston to provide a two-stage oil feed rate characteristic, and the first cylinder is moved in the axial direction. Since the oil feed rate is changed by moving the oil feed rate to , the oil feed rate can be controlled more easily than a control method using a solenoid valve.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a diagram showing the oil feed rate characteristics of the same. DESCRIPTION OF SYMBOLS 1... Pump body, 2... Pump chamber, 3... Drive shaft, 7... Barrel part, 8... First cylinder, 9...
...Plunger, 10...Cam means, 11...Cam disc, 12...Coupling, 13...Roller, 14...Roller holder, 17...Timer, 18...
...Second cylinder, 22...Pressure piston, 24.
...First pressure chamber, 26...Second pressure chamber, 28...
・First pressure relief boat, 29... communication passage, 30.
... Check valve, 31 ... Suction passage, 37 ... Discharge part,
38... Distribution and discharge passage, 47... First electromagnetic actuator, 48... Control sleeve, 51...
...Second electromagnetic actuator, 52...Diagonal groove, 5
5...Cutoff groove, 56...Second pressure relief boat.

Claims (6)

[Claims] 1. A pump body that constitutes a pump chamber in which fuel is stored, a drive shaft that is rotatably supported by the pump body, and a drive shaft that is slidably inserted into a barrel portion provided on the pump body and that is synchronized with the drive shaft. a first cylinder that rotates;
a plunger slidably fitted into the first cylinder; a cam means for converting the rotation of the drive shaft into a reciprocating rotational motion of the plunger; a timer connected to the cam means; a second cylinder which has an inner diameter smaller than that of the cylinder, is fitted into the first cylinder and is fixed to the pump body; and a second cylinder which is slidably fitted into the second cylinder and which is connected to the plunger a pressure-feeding piston having one end in contact with the pump chamber; a control sleeve fitted onto a portion of the first cylinder facing the pump chamber; a first driving means for driving the first cylinder in the axial direction; a second driving means for driving the sleeve in the circumferential direction, the first driving means being surrounded by the first cylinder, the plunger, the second cylinder and the pressure-feeding piston;
A pressure chamber is configured, and a first pressure relief port is formed in the first cylinder so as to communicate the first pressure chamber and the pump chamber until the plunger is displaced by a predetermined stroke from the bottom dead center. , a second pressure chamber is constituted by being surrounded by the second cylinder and the pressure-feeding piston, and a suction passage that communicates the second pressure chamber and the pump chamber during the suction stroke of the plunger; A distribution/discharge passage is formed in the pump body, the first cylinder, and the second cylinder, and the distribution/discharge passage communicates the pressure chamber and the discharge section provided in the pump body during the discharge stroke of the plunger. A distribution type fuel injection pump, characterized in that a second pressure relief port is formed in the first cylinder, the second pressure relief port being connected to the discharge passage, and the timing of communication with the pump chamber can be changed depending on the circumferential position of the control sleeve. . 2. 2. The distribution type fuel injection pump according to claim 1, wherein the first driving means is controlled according to the operating state of the engine. 3. Claim 1 or 2, wherein the second drive means is controlled according to the operating state of the engine.
Distribution type fuel injection pump as described in Section 1. 4. The cam means includes a cam disk to which the first cylinder and the plunger are connected, a coupling ring that connects the cam disk to the drive shaft, a roller that receives the cam disk, and a roller holder that holds the roller. 4. The distribution type fuel injection pump according to claim 1, wherein a timer and a control sleeve are connected to the roller holder. 5. A diagonal groove is formed on the outer periphery of the control sleeve,
5. The distribution type fuel injection pump according to claim 4, wherein a connecting rod extending from the roller holder is engaged with the diagonal groove. 6. The plunger has a communication passage that communicates the pump chamber and the first pressure chamber, and the communication passage is provided with a check valve that prevents the flow of fuel from the first pressure chamber to the pump chamber. A distribution type fuel injection pump according to claims 1 to 5.