JPH11336633A - Inner surface cam type fuel injection pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately manufacture a connection structure eliminating axial deviation of a driving shaft and a rotor, and suppress increase of abrasion of a connection part by optionally designing the relation between the power transmitting position from the driving shaft to the rotor and the plunger position. SOLUTION: A radially projected ball pin 50 is formed on a rotor 5. An end of a driving shaft 3 is provided with a recession housing an end of the rotor 5, and a slitting 54 radially formed continuously therefrom. The end of the rotor 5 is housed in the recession of the driving shaft 3, while the ball pin 50 is housed in the slitting 54, for connecting the rotor 5 to the driving shaft 3. Torque of the driving shaft 3 is transmitted to the rotor 5 through the ball pin 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distribution type fuel injection pump for supplying fuel to an engine, and in particular, a plunger is provided in a rotating rotor in a radial direction, and the plunger is reciprocated by a cam ring to form the rotor. The present invention relates to an internal cam type (VR type) fuel injection pump that changes the volume of a pump working chamber.

[0002]

2. Description of the Related Art In a fuel injection pump of this type, a drive shaft is connected to a rotatably provided rotor with its axis aligned.
The configuration disclosed in JP 06875 is known.

In order to connect a drive shaft and a rotor (distribution shaft), a connection head is provided on the drive shaft, and a plurality of (four or three) axial slits extending in the radial direction are formed in the connection head. Then, a connecting plate is fitted to the connecting head, a connecting web formed integrally with the connecting plate is housed in the axial slit, and a pin protruding from an end face of the rotor is inserted into a notch formed in the center of the connecting plate. The drive shaft and the rotor are inserted so as to be pivotally connected in a cardan manner. Of the plurality of connecting webs formed in the connecting plate, two connecting webs are accommodated in the axial slit so as to have no play in the circumferential direction, and the notch of the connecting plate and the pin of the rotor are It is pivoted, leaving play in the direction of. In the same publication, a spherical enlarged portion is formed on the connecting web,
It is also shown that this enlarged portion accommodates the connecting web in the axial slit without any play in the circumferential direction.

[0004]

However, in the above-described configuration, a connecting plate is interposed between the drive shaft and the rotor in order to obtain a connection structure that absorbs the axial deviation between the drive shaft and the rotor. However, according to such a configuration,
Rotational power is received at the shaft end of the rotor provided with the connecting plate, frictional force generated between the rotor and the cam ring in the middle of the rotor provided with the plunger, and a portion receiving the power and a portion receiving the frictional force. Are shifted in the axial direction of the rotor. As a result, there is a concern that the balance of the force applied to the connecting portion may be impaired and the wear of the connecting portion (wear of the connecting web) may increase.

[0005] The axial displacement between the portion receiving the power and the portion receiving the frictional force does not generally cause the above-described disadvantage because it has an allowable range per se. Since the connecting plate can be attached only to the shaft end of the rotor, the balance of force cannot be adjusted by changing the position of the connecting plate.

Further, since the connecting web formed integrally with the connecting plate is formed in a plate shape, it is difficult to accurately form a spherical enlarged portion on the connecting web.
It has been pointed out that the lower the processing accuracy, the smaller the allowable range in which the axis deviation between the drive shaft and the rotor can be absorbed.

Therefore, in the present invention, in the internal cam type fuel injection pump, when connecting the drive shaft and the rotor, the connection structure for absorbing the axis deviation between the drive shaft and the rotor is improved, and such a structure is improved. An inner cam that can be manufactured with high precision, and that allows the design of the relationship between the power transmission position from the drive shaft to the rotor and the position of the plunger to be freely changed in the axial direction of the rotor, thereby suppressing an increase in wear of the connecting portion. It is an object to provide a fuel injection pump of the type.

[0008]

In order to achieve the above object, the present invention provides a drive shaft for transmitting external power,
A rotor connected to the drive shaft so as to have an axial center;
A cam ring provided around the rotor, and a plunger which faces a pump working chamber formed inside the rotor and is displaced in the radial direction of the rotor by the cam ring, wherein the fuel compressed in the pump working chamber is provided. In the internal cam type fuel injection pump for distributing and pumping, the rotor is provided with a ball pin projecting in the radial direction, and a concave portion for accommodating the end of the rotor is formed at the end of the drive shaft, and is formed in the radial direction following the concave. Having a slit provided therein, accommodating an end of the rotor in a recess of the drive shaft, accommodating the ball pin in the slit, connecting the rotor and the drive shaft, and The rotary power is transmitted to the rotor via the ball pin (claim 1).

Here, the ball pin provided on the rotor may be separate from or integral with the rotor. If the ball pin is separate from the rotor, for example, after being attached to the rotor, the ball pin may be used for welding or the like. It is desirable to securely fix the rotor to the rotor by means. If it is integral, it may be integrally formed at an arbitrary position on the rotor peripheral surface by cutting or the like, and in any case, the protruding end The part may be rounded spherically and the rounded end may be accommodated in the slot of the drive shaft without play in the circumferential direction of the rotor.

According to such a configuration, when the drive shaft rotates, the rotational power is transmitted to the rotor via the ball pin accommodated in the slit of the drive shaft, and the rotor rotates. The drive shaft and the rotor are mounted so that their axes are aligned. However, there may be a case where the axes are shifted due to a manufacturing error or an installation error. However, even in such a case, the connection between the drive shaft and the rotor is realized by fitting a ball pin protruding in the radial direction of the rotor into a slit of the drive shaft. , Or can be accurately machined by shaving or the like, so that the allowable range in which the deviation of the axis between the drive shaft and the rotor can be absorbed can be increased.

The ball pin may be provided so as to be shifted from the position of the plunger in the axial direction of the rotor. However, in consideration of the balance of the force at the connecting portion between the drive shaft and the rotor, the position of the ball pin is considered. And the position of the plunger may be matched in the axial direction of the rotor. (Claim 2).

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show an internal cam type distribution type fuel injection pump. In this fuel injection pump 1, a drive shaft 3 is inserted into a pump housing 2, and one end of the drive shaft 3 is connected to the outside of the pump housing 2. And receives a driving torque from an engine (not shown), and rotates in synchronization with the engine (at half the engine speed).

The pump housing 2 includes a housing member 2a for holding a drive shaft 3 and a housing member 2a.
a housing member 2b provided with the delivery valve 4 and the like, and a housing member 2c provided on an extension of a rotor 5 described later by closing an opening of the housing member 2b. .

A rotor support member 6 is fitted in the pump housing 2, and a space surrounded by the rotor support member 6 forms a fuel chamber 7. The fuel chamber 7 communicates with a governor storage chamber 9 defined by a governor housing 8 through a through hole (not shown).

The governor housing 8 is provided with a governor housing member 8 mounted on an upper portion of the housing member 2a.
a, and a governor housing member 8b to which an upper opening of the governor housing member 8a is closed and to which an overflow valve 10 is attached.

A feed pump 11 fixed to the drive shaft 3 is housed in the pump housing 2.
The fuel supplied into the housing by the feed pump 11 is somewhat pressurized. The fuel passage 1 extends from the outlet side of the feed pump 11 to the governor chamber 9 in the housing member 2a and the governor housing member 8a.
The fuel pressurized by the feed pump 11 is supplied to the governor storage chamber 9 through the fuel passage 12. A fuel cut valve 13 is provided in the middle of the fuel passage 12,
Is closed when a request to stop the pump is made.

The rotor 5 connected to the drive shaft 3 is rotatably supported by the rotor support member 6. The rotor 5 is rotatably supported in an oil-tight and rotatable manner in an insertion hole 14 formed in the rotor support member 6.
a is engaged with the drive shaft 3 so that only the rotation is allowed as the drive shaft 3 rotates. An insertion hole 5b for inserting the lancer 15 in a radial direction (radial direction) is formed in a base end portion 5a of the rotor 5, and the plunger 15 is slidably accommodated in the insertion hole 5b. The two plungers 15 are provided on the same plane at an interval of 180 degrees, and the tip of each plunger 15 closes a pump working chamber 16 provided at the center of the base end of the rotor 5. , The plunger 15 moves along the inner surface of the cam ring 19 via the shoe 17 and the roller 18.

The cam ring 19 is a ring-shaped member provided concentrically around the rotor 5, and has a cam surface having a number of cam lobes corresponding to the number of cylinders of the engine formed on an inner surface thereof.
When the rotor 5 rotates, the radial direction (radial direction) of the rotor 5
The plungers 15 can be reciprocally moved, and the volume of the pump working chamber 16 can be varied.

That is, a fuel inlet 20 is formed on the side of the pump housing 2, and the fuel flowing into the housing from the fuel inlet 20 flows around the connection between the rotor 5 and the drive shaft 3 and the cam ring 19. The plunger 15 is guided to the inlet side of the feed pump 11 through a space or the like formed between the shoe 17 and the pump 17. This is performed using the pressure difference between the pressure and the fuel pressure on the low pressure side flowing outside the shoe 17, and the inward movement is determined by the cam surface of the cam ring 19. If the cam ring 19 is formed so as to correspond to four cylinders, cam lobes are formed on the inner surface every 90 degrees, so that the two plungers 15 are simultaneously held so as to sandwich the pump operation chamber 16. It moves and moves away from the center of the cam ring 19 at the same time.

A spring accommodating chamber 21 is formed between the base 5a of the rotor 5 and the connecting head 3a of the drive shaft 3, and a spring 22 composed of a compression coil spring is elastically mounted in the spring accommodating chamber 21. The spring 22 constantly urges the rotor 5 in the axial direction away from the drive shaft 3. In addition, a snap ring 24 is provided via a shim 23 at an end opposite to the base end 5 a urged by the spring 22, that is, at a tip end of the rotor 5.
In the event that the sprig 22 is broken, the movement of the rotor 5 in the axial direction is restricted.

The rotor 5 has a vertical hole 25 formed in the axial direction thereof and leading to the pump working chamber 16, an inflow / outflow port 26 communicating with the vertical hole 25 and opening on the peripheral surface of the rotor 5,
One end is connected to the vertical hole 25 and the other end is formed with a discharge port 28 intermittently communicating with a pressure feed passage 27 communicating with the delivery valve 4.

The inflow / outflow port 26 is opened at a portion located in the fuel chamber 7 on the peripheral surface of the rotor 5, and this opening is covered by a control sleeve 31 slidably fitted to the rotor 5. An engagement groove extending in the circumferential direction is formed at an upper portion of the control sleeve 31, and an engagement ball 34 formed at a tip of a shaft 33 of the electric governor 32 is engaged with the engagement groove. .
The engaging ball 34 is provided eccentrically with respect to the shaft 33, and the shaft 33 is provided by an external signal.
When is rotated, the control sleeve 31 moves in the axial direction of the rotor 5. The control sleeve 31 is provided with a through hole, for example, in the radial direction, and the inflow / out port 26 is connected to the fuel chamber 7 only through the through hole.
It is possible to communicate with.

The timing at which communication between the inflow / outflow port 26 and the through hole of the control sleeve 31 is cut off is fixed regardless of the axial position of the control sleeve 31.
Timing of communication with the through hole (at the start of cutoff)
Is faster as the control sleeve 31 is moved leftward in the figure (toward the base end of the rotor 5). Further, as the control sleeve is moved to the right (toward the tip end of the rotor 5), the communication timing (at the start of cutoff) between the inflow / outflow port 26 and the through hole of the control sleeve 31 is delayed.

An engagement groove extending in the axial direction is formed in a lower portion of the control sleeve 31, and the locking member 3 fixedly mounted on the rod 36 held by the rotor support member 6.
7 is locked in this engagement groove. This rod 36
The arm portion 38 extending in the radial direction is engaged with the connecting piece 39 fixed to the cam ring 19, so that the control sleeve 31 rotates with a predetermined relationship when the cam ring 19 rotates. .

The amount of rotation of the cam ring 19 is controlled by a timer device 40.
The timer device 40
Accommodates a timer piston 42 slidably in a cylinder 41 provided in the housing 2.
2 is connected to the cam ring 19 via the lever 43, and the movement of the timer piston 42 is converted into the rotation of the cam ring 19.

At one end of the timer piston 40, a high-pressure chamber 45 into which high-pressure fuel from the fuel chamber is introduced, and at the other end, a low-pressure chamber 46 communicating with a low-pressure oil passage leading to the inlet side of the feed pump 11, respectively. A timer spring 47 is elastically mounted in the low-pressure chamber 46.
7, the timer piston 42 is constantly urged toward the high-pressure chamber. Therefore, the timer piston 42 stops at a position where the spring pressure of the timer spring 47 and the differential pressure between the high pressure chamber pressure and the low pressure chamber pressure are balanced, and when the high pressure chamber pressure increases, the timer piston 42 Move to the low pressure side in opposition. As a result, the cam ring 19 is rotated in a direction to advance the injection timing, and the cam ring 1
The control sleeve 31 connected to the motor 9 is also rotated in the same direction, and the injection timing is advanced.

When the high-pressure chamber pressure decreases, the timer piston 42 is moved toward the high-pressure chamber by the spring force of the timer spring 47, and the cam ring 19 is rotated in a direction that retards the injection timing. The control sleeve 31 also rotates in the same direction, and the injection timing is delayed.

The pressure in the high-pressure chamber 45 of the timer device 40 is adjusted by a timing control valve (TCV) 48 so as to obtain a required timer advance angle. Is designed to advance the timer advance by increasing the high pressure chamber pressure.

Therefore, when the rotor 5 rotates, the number of inflow / outflow ports 26 corresponding to the number of cylinders sequentially communicates with the through holes of the control sleeve 31, and during the suction stroke, the number of outflow / inflow ports 26 of the rotor 5 is controlled. Sleeve 31
And the fuel in the fuel chamber 7 is
6 and moves the plunger 15 in a direction away from the center of the cam ring 19 against the fuel pressure on the low pressure side.

Thereafter, the plunger 15 is moved to the cam ring 19.
As a result, the communication between the inflow / outflow port 26 and the through hole of the control sleeve 31 is cut off, the discharge port 28 and one of the pressure feed passages 27 are aligned, and the compressed fuel is discharged. It is delivered to the delivery valve 4 via the delivery passage 27, from where it is delivered to the injection nozzle via the injection pipe.

When the communication portion 35 of the control sleeve 31 and the next outflow / inflow port 26 communicate with each other again in the middle of the pressure feeding process, the compressed fuel flows into the fuel chamber 7, and the fuel pressure in the injection pipe is reduced at once. And the fuel injection from the injection nozzle ends. The fuel pumping timing is controlled by the timer device 40, and the injection amount is controlled by the control sleeve 31, so that the above processes are sequentially repeated, so that the required amount of fuel is required for the engine. It is supplied at the timing.

The connection between the rotor 5 and the drive shaft 3 is made by a ball pin 50 provided on the rotor 5. Hereinafter, this point will be described. As shown in FIG. 3, a guide rib 51 projecting in the radial direction is provided at the base end portion 5a of the rotor 5 in the same phase as the insertion hole 5b in the circumferential direction of the rotor 5. The guide ribs 51 integrally hold the shoe 17 and the roller 18 so as not to shift in the axial direction. The ball pin 50 is inserted into the insertion hole 5 b for inserting the plunger 15 or the guide rib 5.
It is formed at a position shifted by 90 degrees from 1.

On the other hand, the coupling head 3a of the drive shaft 3
A concave portion 52 for receiving the base end portion 5a of the rotor 5 with a sufficient clearance is formed in the axial direction of the drive shaft from the shaft end, and the first and second slits 53 are formed radially following the concave portion 52. , 54 are formed.

The first slits 53 are for accommodating the guide ribs 51 of the rotor 5 and are formed with two phases shifted by 180 degrees. The second slit 54 is formed at one position with a phase shift of 90 degrees with respect to the first slit 53 so that the ball pin 50 is housed in the second slit 54. Has become. The second slit 54 is formed to be shallower from the shaft end of the connecting head 3a than the first slit 53.

Ball pin 50 attached to rotor
Are formed in a columnar shape, are press-fitted or screwed into the base end learning wall of the rotor 5, and are attached so as to protrude in the radial direction of the rotor 5. In order to prevent the ball pin from loosening over time, the ball pin and the rotor are further securely fixed by welding or other means, and the tip is slightly enlarged in diameter and rounded in the axial direction to form a spherical shape Have been. The guide rib 51 of the rotor 5 is accommodated in the first slot 53 with a certain amount of play, while the ball pin 50 provided on the rotor 5 has a tip portion of the rounded ball pin 50. The rotor 5 is accommodated in the second slit 54 without play in the circumferential direction.

In this configuration example, the ball pin 50
Is located at the center in the axial direction of the base end portion 5a, that is, the center line of the plunger 15 and the center line of the ball pin 50 are the same position in the axial direction of the rotor.

In the above configuration, when the drive shaft 3 rotates, the rotational power is transmitted to the rotor 5 via the ball pin 50 which is accommodated in the second slit 54 and abuts on the connecting head 3a in the circumferential direction. , The rotor 5 starts to rotate at the same time. The drive shaft 3 and the rotor 5 are circumferentially abutted only by the ball pin 50, and
Can be displaced in the axial direction of the rotor 5 and the axial direction of the ball pin 50, so that the axis of the drive shaft 3 and the axis of the rotor 5 are shifted due to a manufacturing error or an assembly error. Even if this can be absorbed.

In particular, in this example, since the tip of the ball pin 50 is rounded spherically and is in point contact with the drive shaft 3,
The structure is such that the deviation of the axis between the drive shaft 3 and the rotor 5 can be more easily absorbed. Further, since the axis of the ball pin 50 and the axis of the plunger 15 are in the same position in the axial direction,
A portion of the rotor 5 to which power is transmitted from the drive shaft 3, that is,
The portion where the ball pin is provided and the portion where the frictional force is generated between the cam ring and the portion where the plunger is provided coincide in the axial direction of the rotor, and are applied to the connecting portion between the drive shaft 3 and the rotor 5. The balance of the force is improved, and the wear of the ball pin 50 can be reduced.

Further, since the ball pin 50 and the rotor are originally formed as separate members, it is easy to process the ball pin alone before mounting the ball pin on the rotor, or to perform wear resistance such as quenching or plating. Thus, the structure of the connecting portion of the rotor can be simply and accurately formed.

FIGS. 5 and 6 show examples in which the positions of the ball pins 50 provided on the base 5a of the rotor 5 are different from each other. In this example, the position of the ball pins 50 is changed to the position of the plunger 15. The second slit 54 formed on the connecting head 3a is also formed shallower from the shaft end of the connecting head 3a.

Such a configuration is achieved by connecting the drive shaft 3 to the rotor 5
Is displaced in the axial direction of the rotor from the part where power is transmitted to the part and the part where the frictional force is generated between the plunger 15 and the cam ring 19, but such a deviation greatly disturbs the balance of the force and hinders operation. In the case where the result does not result, the machining amount of the second slit 54 (the dimension from the shaft end of the connecting head 3a) can be reduced, so that the machining of the drive shaft 3 becomes easy, and the plunger 15 is inserted. By separating the hole 5b and the position where the ball pin 50 is formed, the base end 5a of the rotor 5
This is advantageous for ensuring the strength of the sheet.

The above configuration is composed of the ball pin 50 and the rotor 5
In this example, the ball pin is formed integrally with the rotor, as shown in FIG.
The ball pin 50 having such a configuration is formed on the peripheral wall of the base end portion of the rotor 5 by a method such as shaving, and is formed in a cylindrical shape protruding in the radial direction of the rotor 5, and the tip portion has a diameter. This is similar to the above-described configuration example in that it is somewhat enlarged to form a spherical shape.

According to such a configuration, not only can the axis deviation between the ball pin and the rotor be sucked, but also the position of the ball pin and the plunger can be made the same in the axial direction by a design change, and the balance of the force can be achieved. Can be displaced in the axial direction within a range that does not cause trouble, and furthermore, it is not necessary to loosen the ball pin over time or take measures to prevent it.

[0044]

As described above, according to the present invention,
A ball pin is provided on the rotor so as to protrude in the radial direction, and the ball pin is fixed to the rotor by accommodating the ball pin in the slit of the drive shaft to realize the connection structure between the drive shaft and the rotor. In spite of this, the allowable range in which the deviation of the axis between the drive shaft and the rotor can be absorbed increases.

Further, according to the structure of the present invention, the axial position of the rotor on which the ball pin is mounted can be freely changed in design, so that the force balance of the connecting portion can be adjusted by the position of the ball pin. By setting the position of the rotor receiving power from the drive shaft and the position of the plunger at the same position in the axial direction of the rotor, it is possible to contribute to reduction of wear of the ball pin.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view schematically showing an inner cam type fuel injection pump according to the present invention, and FIG.
It is sectional drawing which shows a part cut | disconnected by the II line of FIG.1 (a).

FIG. 2 is a cross-sectional view showing a cross section perpendicular to the axis of a rotor so that a cam ring and a timer device of the inner cam type fuel injection pump shown in FIG. 1 are exposed.

3 (a) is a side view showing a rotor of the inner cam type fuel injection pump shown in FIG. 1, and FIG. 3 (b) is cut along a line II-II in FIG. 3 (a). It is sectional drawing.

4 (a) is a partially cutaway sectional view showing a drive shaft of the inner cam type fuel injection pump according to the present invention, and FIG. 4 (b) is a sectional view of FIG. 4 (a). FIG. 4 is a cross-sectional view of a connection portion where the rotor shown in FIG.

FIG. 5 is a cross-sectional view showing a configuration in which a mounting position of a ball pin provided at a connecting portion between a drive shaft and a rotor of the inner cam type fuel injection pump according to the present invention is different.

6 (a) is a side view showing a rotor of the inner cam type fuel injection pump shown in FIG. 5, and FIG. 6 (b) is cut along a line III-III in FIG. 6 (a). It is sectional drawing.

7A is a side view showing a configuration example in which a rotor and a ball pin of an inner cam type fuel injection pump are integrally formed, and FIG. 7B is a side view of FIG. 7A. It is sectional drawing cut | disconnected by the -IV line.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel injection pump 3 Drive shaft 5 Rotor 15 Plunger 16 Pump working chamber 19 Cam ring 50 Ball pin 52 Depression 53 First slit 54 Second slit

Continued on the front page (72) Inventor Takamitsu Kuroda 3-13-26 Yaumicho, Higashimatsuyama-shi, Saitama Inside of Zexel Higashimatsuyama Plant

Claims (2)

[Claims] 1. A drive shaft for transmitting power from the outside, a rotor connected to the drive shaft so as to have an axial center, a cam ring provided around the rotor, and a rotor formed inside the rotor. A plunger facing the pump working chamber, the plunger being displaced in the radial direction of the rotor by the cam ring, and an inner cam type fuel injection pump for distributing and pumping the fuel compressed in the pump working chamber. A protruding ball pin is provided, and a concave portion for accommodating the end of the rotor is provided at an end of the drive shaft, and a slit formed in a radial direction following the concave portion. And the ball pin is housed in the slit and the rotor and the drive shaft are connected to each other, and the rotational power of the drive shaft is transmitted to the rotor via the ball pin. Inner surface cam type fuel injection pump, characterized in that the the like. 2. The internal cam type fuel injection pump according to claim 1, wherein the position of the ball pin and the position of the plunger are the same in the axial direction of the rotor.