JPH11210586A - Inside face cam type fuel injection pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a rotor from moving in the force feed quantity increasing direction by providing a spring energizing the rotor in the force feed reducing direction and a snap ring, which is fitted in a recess part formed around the rotor so as to prevent the rotor from moving in the opposite direction to the energizing direction by the spring. SOLUTION: By means of a spring 21 elastically arranged in the connection part between a base end part 5a in a rotor 5 and a driving shaft 3, the rotor 5 is always energized in the direction in which the rotor 5 is separated from the driving shaft 3. In the rotor 5, in the tip part on the opposite side to the base end part energized by means of the spring 21, a snap ring 23 is arranged via a shim 22, so that axis directional movement of the rotor 5 is restricted. A ring type recess part, in which the snap ring 23 is fitted, is formed in the tip part of the rotor 5, and on the end face of a rotor supporting member 6, the snap ring 23 is locked in the axial direction via the shim 22. In this way, the rotor can be prevented from moving in the force feed quantity increasing direction.

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, in particular, a plunger is slidably provided in a rotor rotating in synchronization with the engine in a radial direction, and the plunger is reciprocated by a cam ring. The present invention relates to a distribution type fuel injection pump (inner cam type fuel injection pump) of a type that changes the volume of a compression chamber formed in a rotor by moving the same.

[0002]

2. Description of the Related Art This type of fuel injection pump is disclosed in, for example, Japanese Patent Application Laid-Open No.
As disclosed in Japanese Patent Publication No. 3 (1993) -A3, a concentric cam ring is arranged around a rotor, and a plunger is applied to a cam surface formed inside the cam ring via a roller or the like. It reciprocates in the direction. The rotor has a compression chamber whose volume changes due to the reciprocating motion of the plunger, a suction hole for sucking fuel into the compression chamber during the suction process, a distribution port for delivering fuel pressurized by the compression chamber during the pumping process, and fuel delivery. An overflow port is formed to cut off. Further, a control sleeve is externally fitted to the rotor so as to cover the overflow port, and by moving the control sleeve in the axial direction, the cutoff time at the time of the pumping process can be changed and the pumping amount can be varied. I have to.

In such an injection pump, when a sliding contact portion between a rotor and a member supporting the rotor is worn over a long period of use, and this causes rattling in the axial direction of the rotor,
The relative position between the rotor and the control sleeve cannot be determined uniformly, and the pumping amount of the injection pump fluctuates. Therefore, in view of the fact that the injection nozzle leading to the injection pump has a structure in which the injection amount increases over time, the present applicant always urges the rotor by a spring in the direction in which the pressure-feeding fuel decreases. And the amount of fuel supplied from the injection pump is changed over time with the wear at the sliding contact part, and the change over time is offset by the change over time due to the injection nozzle. We have already filed an application for technology that minimizes this.

Further, in the configuration in which the pumping fuel of the injection pump is reduced in accordance with the wear of the rotor, even when the injection pump is evaluated independently, the pumping amount increases with time or the rotor rattles. It can be said that the configuration is more desirable in terms of safety measures than that in which the amount of pumping varies.

[0005]

However, as described above, in the injection pump in which the amount of pumping is reduced over time by using a spring, if the spring is damaged for any reason, the rotor tends to increase the amount of pumping. It may be displaced.

In this regard, in the earlier application filed by the present applicant, a stopper is screwed into an end opposite to the end of the rotor urged by a spring to restrict the axial movement of the rotor. As a result, the rotor is prevented from being displaced in the direction of increasing the pumping amount, and a thorough countermeasure is taken. However, even with such a configuration, it cannot be said that there is no possibility that the screwed state of the stopper is loosened, and the spring is broken, and if the stopper is loosened, the rotor can be displaced in the direction of increasing the pumping amount. There is.

Therefore, according to the present invention, even if a spring for urging the rotor in a direction to reduce the fuel is broken, the internal cam type fuel injection is intended to surely eliminate the possibility of an increase in the fuel pumped by the injection pump. It is an object to provide a pump.

[0008]

In order to achieve the above object, a rotor rotatably supported by a support member and a compression member provided on the rotor so as to be slidable in a radial direction of the rotor. A plunger that varies the volume of the chamber, a cam ring that is provided concentrically around the rotor, and reciprocates the plunger in the radial direction of the rotor with the rotation of the rotor, A control sleeve that controls the amount of fuel pumped by adjusting the relative position in the axial direction with respect to the rotor, a spring that urges the rotor in the direction of decreasing the pumped amount, It is provided at the end of the rotor and fits into a recess formed on the peripheral surface of the rotor to prevent the rotor from moving in the direction opposite to the biasing direction by the spring. It is characterized by comprising a snap ring.

Here, the spring for urging the rotor in the direction of decreasing the pressure feed amount is constituted by a compression coil spring elastically mounted between the rotor and a drive shaft connected to the rotor and transmitting the power of the engine. The snap ring may be provided at the end opposite to the end of the rotor on which the spring is provided, and more specifically, the snap ring prevents movement of the rotor. An annular recess may be formed on the support member, and the snap ring may be directly or indirectly engaged with the support member of the rotor via a shim in the axial direction.

Therefore, in normal times, the rotor is constantly urged by the spring in the direction of decreasing the pumping amount, so that abrasion occurs at the sliding contact between the rotor and a member supporting the rotor. Even in the case where the restriction on the direction is relaxed, the rotor is not moved in the direction of increasing the pumping amount. Even if the spring is broken and the bias on the rotor is no longer effective, the snap ring prevents the rotor from moving in the direction of increasing the pumping amount. Is gone.

[0011]

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 distribution type 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 pump housing 2 by a 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).

A 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 has a governor storage chamber 9 defined by a governor housing 8 mounted on an upper portion of the housing member 2a.
And through a through hole (not shown). Further, a feed pump 10 fixed to the drive shaft 3 is accommodated in the pump housing 2, and the fuel supplied by the feed pump 10 into the housing is somewhat pressurized. 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 manner in an insertion hole 11 formed in the rotor support member 6, and its base end 5 a is mounted between engagement pieces formed on the drive shaft 3. Then, only the rotation is allowed along with the rotation of the drive shaft 3. A plunger 12 is slidably inserted in the proximal end 5a of the rotor 5 in the radial direction (radial direction). Two (or four) plungers 12 are provided on the same surface at an interval of 180 degrees (or 90 degrees), and the tip of each plunger 12 is located at the center of the base end of the rotor 5. , The plunger 12 moves on the inner surface of the cam ring 16 via the shoe 14 and the roller 15.

The cam ring 16 is a ring-shaped member provided concentrically around the rotor 5. Cam lobes corresponding to the number of cylinders of the engine are formed on the inner surface, and when the rotor 5 rotates, each plunger 12 causes the rotor 5 to rotate. Radial direction (radial direction)
And the volume of the compression chamber 13 is made variable. That is, if the cam ring 16 is formed corresponding to four cylinders, a convex curved surface is formed inside the cam ring 16 at every 90 degrees, and therefore, two (or four) plungers are formed. Numerals 12 move simultaneously so as to sandwich the compression chamber 13 and move away from the center of the cam ring 16 at the same time.

The base 5a of the rotor 5 and the rotor support member 6
A washer 17 is provided between the rotor and the rotor 5 to prevent the rotor 5 from directly contacting the rotor support member 6 and to form a sliding contact portion on both surfaces of the washer 17 to reduce wear of the rotor 5. . A spring accommodating chamber 20 is formed at a connection portion between the base end portion 5a of the rotor 5 and the drive shaft 3, and a spring 21 made of a compression coil spring is elastically mounted in the spring accommodating chamber 20. Is constantly biased in a direction away from the drive shaft 3.

Further, as shown in FIGS. 3 and 4, a snap ring is provided at the end opposite to the base end urged by the spring 21, that is, at the tip end of the rotor 5, via a shim 22. 23 are provided to restrict the movement of the rotor 5 in the axial direction. The snap ring 23 forms an annular recess 24 around the tip of the rotor 5, and the snap ring 23 is fitted into the annular recess 24, whereby
A snap ring 23 is attached to the end face of the rotor
It is configured to be locked in the axial direction via 2.

For this snap ring 23, for example, a known C-shaped snap ring may be used. The snap ring 23 can be expanded by inserting a tool into holes 23a formed at both ends. After attaching the shim 22 to the protruding end of the rotor 5, the snap ring may be expanded and fitted into the annular recess 24.

A fuel inlet 19 is formed on the side of the pump housing 2, and fuel flowing into the housing from the fuel inlet 19 is formed between the cam ring 16, the shoe 14, the drive shaft 3, and the like. Feed pump 1 through the space formed, around the connection between rotor 5 and drive shaft 3, and the like.
The fuel which is guided to the suction side of the fuel pump 0 and somewhat pressurized by the feed pump 10 passes through a passage 29 formed in the housing member 2 a and the governor housing 8, and is supplied to the governor storage chamber 9.
And then to the fuel chamber 6.

The rotor 5 has a vertical hole 25 formed in the axial direction thereof and leading to the compression chamber 13, an inflow / outflow port 26 communicating with the vertical hole 25, and opening to the peripheral surface of the rotor 5, and one end thereof. A distribution port 28 connected to the vertical hole 25 and having the other end intermittently communicated with a fuel delivery passage 27 formed in the rotor support member 6 and the housing member 2b is formed.

The inflow / outflow port 26 opens at the surface of the rotor 5 at a position located in the fuel chamber 7, and this opening is covered by a control sleeve 30 slidably fitted to the rotor 5. An engagement groove extending in the circumferential direction is formed in an upper portion of the control sleeve 30, and the engagement groove includes a shaft 3 of the electric governor 32.
The engagement ball 34 formed at the tip of the third is engaged. The engagement ball 34 is provided eccentrically with respect to the shaft 33, and when the shaft 33 is rotated by an external signal, the control sleeve 30 moves in the axial direction of the rotor 5. The control sleeve 30 has a through hole (not shown) that can communicate with the inflow / outflow port 26.

The specific configuration of the inflow / outflow port 26 and the through hole of the control sleeve 30 is described in, for example,
As shown in JP-A-61180, the timing at which the communication between the inflow / outflow port 26 and the through hole of the control sleeve 30 is cut off is fixed regardless of the control of the control sleeve 30, and the inflow / outflow port 26 The timing (end of injection) at which the through hole of the control sleeve 30 communicates is advanced as the control sleeve 30 is moved to the left (the base end side of the rotor 5) in the figure, to the right (the tip end side of the rotor 5). It is conceivable that the speed becomes slower as moving to.

An engagement groove extending in the axial direction is formed in a lower portion of the control sleeve 30, and a locking member 36 fixed to the rod 35 held by the rotor support member 6 is formed in the engagement groove. Locked. This rod 35
The radially extending arm portion 37 is engaged with the connecting piece 38 fixed to the cam ring 16, so that the control sleeve 30 rotates in a predetermined relationship when the cam ring 16 rotates. .

The amount of rotation of the cam ring 16 is controlled by a timer device 40. The timer device 40 houses a timer piston 42 slidably in a cylinder 41 provided below the pump housing 2. Then, the timer piston 42 is connected to the cam ring 1 via the lever 43.
6 and the movement of the timer piston 42 is
The rotation is converted to the rotation of No. 6. That is, at one end of the timer piston 42, a high-pressure chamber 45 into which fuel on the chamber side is introduced is formed, and at the other end, a low-pressure chamber 46 communicating with the upstream side of the feed pump is formed.
The timer piston 42 is always urged toward the high pressure chamber by the timer spring 47 mounted on the
2 stops at a position where the spring pressure of the timer spring 47 and the fuel pressure in the high-pressure chamber are balanced, and the high-pressure chamber pressure is controlled by a timing control valve (TC).
V) By adjusting at 44, the amount of rotation of the cam ring 16, that is, the required amount of advance is formed.

In such an injection pump 1, 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 30,
In the suction step in which the plunger 12 moves away from the center of the cam ring 16, the inflow / outflow port 26 of the rotor 5 is aligned with the through hole of the control sleeve 30, and the fuel in the chamber 5 is sucked into the compression chamber 13. Is done.

Thereafter, the plunger 12 is moved to the cam ring 16.
In the pumping process of moving toward the center of the control sleeve 30, the communication between the inflow / outflow port 26 and the through hole 30 of the control sleeve 30 is cut off, and the distribution port 28 and one of the fuel delivery passages 27 are aligned and compressed. Fuel is delivered to the delivery valve 4 via the fuel delivery passage 27, and is fed therefrom to the injection nozzle.

When the through hole of the control sleeve 30 and the next inflow / outflow port 26 communicate with each other again during the pressure feeding step, the compressed fuel flows out into the chamber 7, the pressure feeding to the injection nozzle is stopped, and the injection is stopped. finish. Then, such steps are sequentially repeated, and four cycles are performed per one rotation of the rotor 5 in the above configuration example.

The communication start timing between the inflow / outflow port 26 and the through hole of the control sleeve 30 is adjusted by adjusting the position of the control sleeve 30 as before,
As the control sleeve 30 is moved to the left (drive shaft side) in FIG. 1, the end of the injection is earlier and the pumping amount is reduced,
The closer to the right (toward the tip of the rotor 5), the later the end of injection is delayed, and the pumping amount is increased.

As described above, the pumping amount of the injection pump is controlled by the control sleeve 30.
Even if the position of the control sleeve 30 is the same, the amount of pumping changes because the constraint in the axial direction of the rotor 5 is relaxed. That is, in the case of the above configuration, the sliding contact portion between the base end portion 5a of the rotor 5 and the washer 17, or the washer 1
If the abrasion progresses in the sliding contact portion between the rotor 7 and the rotor support member 6 and rattling occurs in the axial direction of the rotor 5, there is a concern about fluctuations in the pumping amount.

However, since the rotor 5 is urged away from the drive shaft 3 by the spring 21,
Although the inflow / outflow port 26 of the rotor 5 slightly shifts to the right in FIG. 1 with time, it is possible to suppress rattling in the axial direction of the rotor. This means that the pumping amount of the injection pump itself decreases with time, but the injection nozzle connected to the delivery valve 4 via a pipe only has a factor of increasing the injection amount with time. Since it does not have, it is possible to completely or partially offset the decrease of the pumping amount of the injection pump 1 over time and the increase of the injection amount over time of the injection nozzle, and the fuel in the injection system as a whole is seen. The supply does not change significantly over time.

In the event that the spring 21 urging the rotor 5 is broken for some reason, the snap ring 23 is fitted into the annular recess 24 of the rotor 5 and the rotor is supported. Since the rotor 5 is locked to the member 6 in the axial direction via the shim 22 to prevent the rotor 5 from moving in a direction to increase the pressure-feeding fuel, there is no possibility that the rotor 5 is largely displaced toward the drive shaft. Can be prevented from increasing sharply and greatly impairing the injection performance and safety.

In the above configuration, the spring 21
Are disposed at a connection portion between the rotor 5 and the drive shaft 3 so that the rotor 5
Is biased in a direction away from the drive shaft 3,
If the control sleeve 30 moves to the tip side of the rotor and the amount of pressure decreases, the mounting position of the spring 21 and the snap ring 23 is appropriately changed, and the movement is prevented by the biasing direction of the spring 21 and the snap ring 23. The direction in which it is performed may be reversed.

[0033]

As described above, according to the present invention,
A spring that constantly urges the rotor of the internal cam type distribution type fuel injection pump in the direction of decreasing the pumping amount and a snap ring that prevents movement in the direction of increasing the pumping amount are provided. In addition to suppressing the rattling of the rotor which may occur in the event that the spring is broken, the snap ring is fitted into the concave portion formed on the peripheral surface of the rotor and there is no risk of displacement, so the amount of pumping increases. The movement of the rotor in the direction can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view of a distribution type fuel injection pump according to the present invention.

FIG. 2 is a cross-sectional view of the injection pump according to FIG. 1 cut perpendicular to an axis of a rotor so that a cam ring and a timer device appear.

FIG. 3 is an enlarged sectional view showing a tip end portion of the rotor shown in FIG.

FIG. 4 is a perspective view of a tip end portion of the rotor shown in FIG. 3;

[Explanation of symbols]

 Reference Signs List 1 injection pump 3 drive shaft 5 rotor 6 rotor support member 12 plunger 13 compression chamber 16 cam ring 21 spring 23 snap ring 24 annular recess 30 control sleeve

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

Claims (1)

[Claims] A rotor rotatably supported by a support member; a plunger slidably provided in a radial direction of the rotor to change a volume of a compression chamber formed in the rotor; A cam ring provided concentrically around the plunger to reciprocate the plunger in the radial direction of the rotor with the rotation of the rotor, and externally fitted to the rotor and adjusting an axial relative position with the rotor. A control sleeve for controlling the amount of fuel being pumped by a spring; a spring for urging the rotor in a direction to decrease the amount of fuel being pumped; A snap ring that fits into a recess formed in the surface and prevents movement of the rotor in a direction opposite to the biasing direction of the spring. Inner surface cam type fuel injection pump.