JPH10288166A - Fuel feed pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To limit reaction torque of a drive shaft by a simple structure by providing a target breaking portion on the drive shaft and breaking the drive shaft at the target breaking portion when reaction torque exceeds maximum reaction torque stipulated. SOLUTION: A target breaking portion is formed on a drive shaft 21 by working and forming an annular groove 41 on the peripheral surface of the drive shaft 21. The annular groove 41 is directly provided on the cross section transfer part between a forming head 25 and a shaft part of the drive shaft 21. The depth of the annular groove 41 is locked by a gear 5 which is provided within a pump chamber 3 and is revolved and driven by an external driving element and a gear 9 to which the rotary motion of this gear 5 is transmitted via a peripheral surface gear train. When remarkably large return torque is generated, the drive shaft 21 is made to be broken at this portion. In this case, various kinds and different maximum allowable reaction torque in the drive shaft 21 can be adjusted according to the depth of the annular groove 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel feed pump for an internal combustion engine, provided with at least one pump element which is driven in rotation in a pump chamber, the pump element being driven by its rotational movement. , Which feeds fuel from the suction chamber to the discharge chamber along the pressure feeding passage, and is coupled to the drive shaft so as to rotate together with the drive shaft, and the drive shaft is connected to the drive shaft via a coupling element. And a type that can be driven by an external driving element.

[0002]

BACKGROUND OF THE INVENTION German Patent Application No. 19625
In the case of such a fuel feed pump known from U.S. Pat. No. 488, at least one pump element is driven in rotation in a pump chamber, such a pump element in the known feed pump comprising:
It is formed by a rotationally driven gear pair that meshes with each other. The gears of this fuel feed pump, formed as gear feed pumps, were formed from a suction chamber connected to a storage tank between the peripheral surface of the gears and the peripheral wall of the pump chamber containing these gears. The fuel is pumped along a pressure feed passage to a discharge chamber connected to a fuel injection pump. In this case, the first gearwheel is coupled for rotation with the drive shaft of the feed pump, which can be driven by an external drive element via a coupling element. The drive shaft is form-coupled to a first gear, which meshes with a second gear mounted on the casing and transmits a rotational movement to this gear.

[0003] In order to prevent the pump transmission from being destroyed or the part falling off into the coupling chamber or the motor chamber from dropping when the pump transmission is suddenly locked, this known fuel feed pump is used. Are provided with means for limiting the reaction torque of the drive unit inside the pump in case the feed pump is suddenly locked. Since the overload prevention device is formed by a slip clutch provided between the drive element and the drive shaft, when the feed pump transmission is locked, the drive element is locked via the slip clutch by the drive clutch. Further rotation about the axis is possible.

However, this known overload protection device in the form of a slip clutch has the disadvantage that the friction value of the slip clutch can change over a long operating time. This makes it difficult to accurately adjust the maximum allowable reaction torque. In addition, this additional slip clutch requires a great deal of manufacturing effort compared to conventional fuel feed pumps.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to improve a fuel feed pump of the type mentioned at the outset, to eliminate the disadvantages and to limit the reaction torque of the drive shaft.
An object of the present invention is to provide a fuel feed pump provided with an overload prevention device which can be easily manufactured and has a simple structure.

[0006]

In order to solve this problem, according to the structure of the present invention, the drive shaft is provided with a target breaking point, and when the specified maximum reaction torque is exceeded, the drive is performed at the target breaking point. The shaft was broken.

[0007]

According to the fuel feed pump of the present invention for an internal combustion engine, an overload prevention device for limiting a reaction torque of a drive shaft is fed without a large structural labor and a labor during assembly. It has the advantage that it can be provided inside the pump. This is advantageously achieved by providing the drive shaft with a target breaking point which breaks when the specified reaction torque of the feed pump is exceeded. It is particularly advantageous if the target breaking point is formed as a weakening of the drive shaft. This is because the drive shaft does not have to transmit any bending forces and thus the rotational or torsional stiffness can easily be reduced.
The effective cross section at the target breaking point can be easily reduced by cutting out the peripheral surface of the drive shaft. Such a notch can be easily formed as an annular groove. This annular groove can be formed, for example, by undercut (Freistich). Further alternatively, the drive shaft can be provided with a cavity in the form of an axial bore. This cavity preferably extends into the region of the annular groove. Advantageously, the target breaking point of the drive shaft is provided at the end of the drive shaft opposite the external drive element. In this case, it is particularly advantageous if this target breaking point is arranged between a positively connected force-introducing area of the drive shaft to the rotationally driven pump element and the shaft of the drive shaft.

[0008] It is also possible to produce the desired break point by providing another notch in the peripheral surface of the drive shaft or by specially forming a material in this area. To prevent individual breaks of the drive shaft from reaching into the motor chamber, it is advantageous if loss-prevention means are provided.
The loss prevention means fixes the broken piece at the axial position of the drive shaft after the drive shaft is broken. In the embodiment, such a loss prevention means is formed as a safety ring.
This safety ring is applied to the end face of the coupling element. The coupling element has a second end face located opposite the first end face,
It is held against the step of the drive shaft.

A portion of the external drive element and the coupling element which are connected to each other so that they can rotate together (hereinafter such a connection portion is referred to as a rotationally connected connection portion); The rotary connection between the drive shaft and the drive shaft, and the rotary connection between the drive shaft and the pump element on the rotary drive side, preferably the first gearwheel, are positively connected, i.e., by a positive connection. It is advantageous if it is formed as a mating part, but it may alternatively be formed as a frictional connection or a part that is bound by frictional forces or a material connection or connection.

According to the invention, the device for preventing the overload when the feed pump is locked is formed as a target breaking point of the drive shaft, so that the drive shaft can freely rotate continuously when the pump transmission is locked. In addition, destruction of the driving element can be reliably avoided without a large manufacturing effort.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention shown in the drawings will be described.

FIG. 1 shows a first embodiment of the fuel feed pump according to the invention, which is inserted from a storage tank into an internal combustion engine, in particular into a pressure feed line, not shown, which leads to a fuel injection pump of the internal combustion engine. I have. In this case, the first embodiment shown in longitudinal section in FIG. 1 has a pump casing 1 in which a pump chamber 3 is provided. A pair of gears that are rotationally driven and mesh with each other are arranged in the pump chamber. In this embodiment, the upper first gear 5 is rotationally driven by an external drive element 7, which is not shown in detail, and this rotational movement meshes with the first gear 5 via the peripheral teeth. The power is transmitted to the second gear 9. These gears 5, 9 divide the pump chamber 3 into two partial areas (not shown) by means of these teeth meshing parts 11. Of these two partial regions, a first partial region forms a suction chamber and a second partial region forms a discharge chamber. The suction chamber is provided between the tooth groove on the peripheral surface of the first gear 5 and the upper peripheral wall of the pump chamber 3 and between the tooth groove on the peripheral surface of the second gear 9 and the lower peripheral wall of the pump chamber 3. Formed between
They are connected to the discharge chamber via one pressure feed passage (not shown in detail). For this purpose, the suction chamber and the discharge chamber each have one connection opening in the wall of the pump housing 1. Via this connection opening, the suction chamber is connected to a suction line, also not shown, leading to the storage tank, and the discharge chamber is connected to a discharge line, not shown, leading to the suction chamber of the fuel injection pump. It is connected.
The pump chamber 3 is closed by a pump cover 13. The two gears 5 and 9 are respectively supported on casing pins that protrude into the inside of the pump casing 1. These casing pins are formed integrally with the pump casing 1. In this case, the upper first casing pin 15 forms a bearing pin for receiving the first gear 5, and the lower second casing pin 17 receives the second gear 9. Form bearing pins. The first casing pin 15 has an axial through hole 19,
The drive shaft 21 is guided in this through hole. The end of this drive shaft which is remote from the housing cover 13 is connected to the external drive element 7 via a coupling element 23 in such a way that it rotates together, that is, in a rotational connection. The end of the drive shaft 21 facing the casing cover 13 projects from the through hole 19 of the first casing pin 15 and has a forming head 25. This forming head protrudes into a forming notch formed corresponding to the first gear 5. The drive shaft 2 is connected via such a shape coupling portion.
The first rotational movement is transmitted to the first gear 5. Drive shaft 21
The end opposite to the pump cover 13 has a pin 29 whose diameter is reduced. This pin of the drive shaft 21 projects into a corresponding receiving opening 31 provided in the disc-shaped coupling element 23. Pin 2 of drive shaft 21 in housing opening 31 of coupling element 23
The rotary connection 9, that is to say the part which is connected so as to rotate with the coupling element 23, may be formed positively or frictionally. Disc-shaped coupling element 23
The annular end face 33 facing the pump casing 1 has a stepped portion 35 formed at a transition portion of the drive shaft 21 to the pin 29.
Has been applied to. Coupling element 23
The end opposite to the end surface 33 has an annular step surface 37.
have. A safety ring 39 inserted into the casing 1 is applied to this annular step surface. Such a safety ring 39 forms a loss prevention means. The loss preventing means fixes the drive shaft 21 at its axial position via the coupling element 23 and prevents the drive shaft portion from slipping out of the pump casing 1 at the time of breakage.

In order to form a target break point of the drive shaft 21, an annular groove 41 is formed on the peripheral surface of the drive shaft 21 as shown in FIG. This annular groove is provided directly in the cross-section transition between the shaping head 25 of the drive shaft 21 and the shaft part. The depth of the annular groove 41 is formed such that the drive shaft 21 breaks at this point when a correspondingly large return torque is generated as a result of the locking of the gears 5 and 9. In this case, various maximum allowable reaction torques of the drive shaft 21 can be easily adjusted according to the depth of the annular groove 41.

In the case of the second embodiment of the fuel feed pump shown in FIG. 3, only the structure of the target break point of the drive shaft 21 is formed differently, so that the illustration and description of this second embodiment will be omitted. This is performed only for the drive shaft 21. In this embodiment, an additional blind hole 43 is machined in the gear-side end face 45 of the drive shaft 21. Since the blind bore extends into the region of the annular groove 41, the effective cross-section of the drive shaft is once again significantly reduced, so that the small maximum permissible reaction torque for shaft breakage is already adjustable at the target breaking point. .

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a fuel feed pump according to the present invention, in which a break portion of a drive shaft is formed by an annular groove.

FIG. 2 is an enlarged view showing a drive shaft of FIG. 1;

FIG. 3 is a simplified view of a drive shaft according to a second embodiment of the fuel feed pump according to the invention, in which the break point is formed by a combination of an annular groove of the drive shaft and an axial blind hole.

[Explanation of symbols]

1 pump casing, 3 pump room, 5 gears,
7 drive element, 9 gear, 11 meshing part,
13 pump cover, 15 casing pin, 1
7 casing, 19 through-hole, 21 drive shaft,
23 coupling element, 25 forming head,
29 pins, 31 receiving openings, 33 end faces, 3
5 steps, 37 annular step surface, 39 safety ring, 41 annular groove, 43 blind hole, 45 end face

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hanspeter Meier Austrian Atnet Atnet 336 B

Claims (10)

[Claims] 1. A fuel feed pump for an internal combustion engine, comprising at least one pump element (5) which is rotationally driven in a pump chamber (3), the pump element having a rotary movement. For pumping fuel from the suction chamber to the discharge chamber along the pressure feed passage and coupled to the drive shaft so as to rotate with the drive shaft (21), wherein the drive shaft is In a type that can be driven by an external drive element (7) via a ring element (23), a target break point is provided on the drive shaft (21), and when a specified maximum reaction torque is exceeded, A fuel feed pump characterized in that the drive shaft (21) breaks at the target breaking point. 2. The fuel feed pump according to claim 1, wherein the target breaking point is formed by a reduced effective cross section of the drive shaft. 3. The fuel feed pump according to claim 2, wherein the cross-section reduction portion is formed by a notch provided on a peripheral surface of the drive shaft (21). 4. The fuel feed pump according to claim 3, wherein the notch in the peripheral surface of the drive shaft (21) is formed as an annular groove (41). 5. The feed pump according to claim 2, wherein the cross-section reduction portion is formed by a hollow chamber provided in a drive shaft (21). 6. The drive shaft according to claim 3, wherein a hollow space formed as an axial hole of the drive shaft is arranged in the region of the notch on the peripheral surface of the drive shaft. Fuel feed pump as described. 7. The drive shaft (21) is provided with a loss prevention means, and the loss prevention means fixes the broken portion at an axial position after the drive shaft (21) is broken. The fuel feed pump according to claim 1. 8. The safety ring (3)
9), wherein the safety ring is applied to the annular step surface (37) of the coupling element (23) and comprises a coupling element (23).
Of the drive shaft (2)
8. The fuel feed pump according to claim 7, wherein the fuel feed pump is held in contact with a step provided in the first step. 9. A pump element (5) driven in rotation.
Is formed as a first gear of a gear pump, said first gear being rotatably supported by a second gear (9).
The fuel feed pump according to claim 1, wherein a pressure feed passage is formed between the peripheral surface of the gear (5, 9) and the peripheral wall of the pump chamber (3). 10. The drive shaft (21) is positively connected to a rotationally driven pump element (5).
Fuel feed pump as described.