EP0199984B1 - Rotary vane vacuum pump - Google Patents

Description

The invention relates to a vane vacuum pump according to the preamble of claim 1. Such a vane vacuum pump is known from DE-OS 29 52 401.

Vane vacuum pumps of this type are used in the use of diesel engines and injection gasoline engines in motor vehicles to create pneumatic brake boosters, the negative pressure generated by the pump being used to boost the brake force. Since the pneumatic system is not particularly susceptible to malfunctions, other servo drives are actuated by means of the negative pressure, such as in particular the gear adjustment, the headlight adjustment, the seat adjustment, etc.

The known vacuum pumps are usually flanged directly to the housing of the drive motor and the drive shaft of the pump is connected directly to a shaft of the drive motor, for example the camshaft, by a coupling. The bearing points of the vacuum pump are lubricated, for example, by an axial bore in the drive shaft of the motor and the shaft of the vacuum pump coupled therewith. In the known vane vacuum pumps of the type mentioned, the lubricating oil entering the hollow shaft of the pump is also conveyed through radial bores into the wing root spaces and used to seal the gaps on the guide surfaces of the wings and to reduce the friction on the wing heads.

The coupling between the drive shaft of the internal combustion engine and the hollow shaft of the vane pump is carried out in known units as a compensating coupling, which ensures safe driving of the pump rotor and compensates for misalignments. It is used as a loose adapter with coupling teeth or drivers with play between the driving shaft on the motor side and the pump shaft.

When installing the vane vacuum pump on the engine block and especially when repairs or replacing a vane vacuum pump, there is a risk that the loose coupling (intermediate piece) to be inserted between the shafts will be forgotten. This happens accidentally when lighting is poor and when working on the engine installed in the vehicle or during repair work and when the components that have been removed or replaced are heavily greased. However, since the lack of the clutch is only determined later when the servo systems are checked, valuable rework is lost through appropriate rework.

From US-A 2 068 803 a vane pump for generating compressed air is known, in which the clutch is held by a cup-shaped element on the rotor shaft, the cup-shaped element being put over the coupling intermediate piece and flanged over a flange of the rotor shaft. This element is disadvantageous because it has a large diameter, because it has to be deformed during assembly and disassembly and because it also projects into the gap between the coupling intermediate piece and the drive shaft and therefore in frictional contact with at least one of the two is coming. The object of the present invention is to avoid these disadvantages and to provide a vane vacuum pump, in which on the one hand the pump rotor and the coupling form a unit for assembly and disassembly, so that it is ensured that the components required for torque transmission without special inspection with the necessary movement play for their function are built in, on the other hand, however, the elements for connecting the pump rotor and the coupling can be installed and detached without any particular deformation and can be installed in the pump without requiring particular space and without wear.

This object is achieved according to the invention by the features specified in the characterizing part of claim 1.

This ensures that the compensating clutch is captively attached to the rotor shaft in the axial direction, so that it can no longer be forgotten or lost during assembly or during repair work in which the vane-cell vacuum pump has to be removed from the engine block.

An advantageous, constructive design and arrangement of the compensating clutch is specified in claims 2 and 3. This solution has the advantage that the radial teeth or drivers of the compensating coupling, which cooperate with the rotor shaft, project axially into the rotor shaft and the bearing housing of the rotor and are preferably flush with the latter. Only the axial teeth or drivers of the compensating coupling, which are intended for engagement with the driving shaft of the motor, protrude axially from the pump housing and are positively inserted into a corresponding radial slot of this shaft during assembly with the drive shaft.

The captive coupling is captively attached to the shaft journal of the rotor by means of a pin which is coaxial with the compensating coupling and the rotor shaft and which can be clamped in the rotor shaft. The attachment can also be accomplished by a pipe which serves to supply the lubricating oil from the lubricating oil supply of the drive motor into the vane vacuum pump and additionally has the function of clamping the coupling to the rotor shaft. Details relating to the structural design of this connecting and fastening pin or pipe are given in claims 4 and 5 to 7 and the following description. With regard to the attachment of the compensating coupling to the rotor shaft, different designs are possible, depending on how easy or difficult it should be possible to separate the components again.

The invention is explained in more detail with reference to the drawing which shows an embodiment.

• Fig. 1 ein axialer Teillängsschnitt einer Flügelzellenvakuumpumpe gemäß Schnitt I-I in Fig. 2;
• Fig. 2 ein Querschnitt der Pumpe gemäß Schnitt 11-11 in Fig. 1;
• Fig. 3a/b alternative Ausführungsbeispiele der Befestigung der Ausgleichskupplung am Wellenzapfen des Pumpenrotors im Teillängsschnitt;
• Fig. 4 die Ausgleichskupplung in der Ansicht und im Querschnitt.

It is:

• 1 shows an axial partial longitudinal section of a vane vacuum pump according to section II in FIG. 2;
• FIG. 2 shows a cross section of the pump according to section 11-11 in FIG. 1;
• 3a / b alternative embodiments of the fastening of the compensating coupling on the shaft journal of the pump rotor in a partial longitudinal section;
• Fig. 4, the compensating coupling in view and in cross section.

The vane vacuum pump shown in Fig. 1 in a partial longitudinal section consists of the pump housing 1, which is tightly closed by a flat turned cover 2, in which an intake port 3 is formed and which is fastened to the housing 1 by screws 4 distributed around the circumference. The pump housing 1 has a cylindrical recess 5 and has, in the housing base 6, an eccentrically arranged bearing eye 7 for one-sided mounting of the shaft journal 8 fixedly attached to the rotor 9. In the rotor 9, for example, four vanes 10 are arranged so as to be radially movable in radial guide slots. For reasons of symmetry, the blades 10 are evenly distributed on the circumference of the rotor 9, two guide slots in each case being diametrically opposed and adjacent blades 10 enclosing a rotor segment of 90 °. To reduce the rotor weight, material recesses, for example axial bores 11, are preferably provided between adjacent wing slots and extend from one end face of the rotor 9 to the other.

The circumference of the housing base is designed as a centering flange 12 in order to be able to fasten the vane vacuum pump to the housing 13 of an internal combustion engine, in particular coaxially to the camshaft 14.

The shaft journal 8, which is mounted in a floating manner in the bearing eye of the housing base 6, has an axial bore 18 which extends to the front end of the rotor 9. Radial bores 15 emanate from this and communicate with the wing root spaces 16 of the wing slots and dip into the axial bore 18 through the coupling pins 17 fastened to the wing feet. If a wing 10 gets stuck or jammed in its retracted position (bottom dead center), this wing 10 is pushed radially outward by the coupling pin 17 of the opposite wing 10 as the rotor 9 continues to rotate.

It should be mentioned that vane cell vacuum pumps of a different design, for example those with two hook-shaped vanes according to DE-OS 35 07 176, are known for which the subject matter of the invention can be applied in an analogous manner.

The axial bore 18 has a central recess or extension 25 in the outer region of the shaft journal 8, into which a compensating coupling 19 with radial play is inserted. 4 is designed as a ring element 26, on the circumference of which two diametrically opposed, radial coupling teeth or drivers 30 are fastened, which engage in a radial slot or correspondingly shaped recesses in the shaft journal 8 in a form-fitting manner. The radial slot or the correspondingly shaped recesses of the shaft journal have such an axial depth that the compensating coupling 19 used in the extension 25 with its ring element 26 and the drivers 30 with the end face of the bearing eye 7 in the plane of the centering flange 12 is essentially flush. The axially opposite drivers 31 of the compensating clutch 19, offset by 90 _° on the circumference, protrude into a slot 20 on the end face of the drive shaft (camshaft 14) and are driven positively by the latter. The compensating coupling and its radial and axial mobility permitted within certain limits can be used to compensate for displacements, in particular axial and / or angular displacement of the two shafts 8, 14 in a simple manner.

The lubricating oil for bearing lubrication and sealing of the vacuum pump is supplied by the oil pump through an axial bore 21 in the drive shaft 14 or is sucked in by the negative pressure generated in the vacuum pump. In this case, between the drive shaft 14 and the shaft journal 8 of the vacuum pump, a connecting tube 23 is provided which is leak-free sealed on the circumference by elastic radial sealing rings 22 and projects into the drive shaft 14 and the shaft journal 9. This connecting tube is inserted with such radial play through the center of the compensating coupling 19 that the compensating movements of the shafts are not hindered.

The oil flow supplied in the shaft journal 8 is injected in the area of the bearing eye 7 through a nozzle 24 into the axial bore 18 of the rotor 9. However, the nozzle 24 is not absolutely necessary for the supply of lubricating oil to the vacuum pump. Further details relating to the connecting pipe 23 and the compensating coupling 19 will be explained later with reference to FIGS. 3 and 4.

According to FIG. 2, in addition to the outlet kidney 28 for the exhaust air and the excess lubricating oil, a relief bore 29 is also provided in the housing base. This is angularly offset from the outlet kidney and is in terms of its level in the highest area of the pump, but its distance from the bearing eye 7 is smaller than the rotor radius, so that it is covered by the rotor end face. The distance of the relief bore 29 from the bearing eye 7 and the radius on which the axial bores 11 of the rotor 9 lie correspond to one another in such a way that the lubricating oil received by the axial bores 11 from the rotor end face flows back without pressure via the relief bore 29 into the oil sump of the drive machine can. This ensures that excess lubricating oil does not lead to an increase in drive power even at high pump speeds and strong oil production. The relief opening 29 can of course also be designed as an elongated hole on the corresponding radius of the axial recesses of the rotor 9.

3a shows in a partial longitudinal section a detail of the shaft connection on an enlarged scale compared to FIG. 1. It can be seen from Fig. 3a that the shaft journal 8 has at its end facing away from the rotor 9 the central extension 25 of the axial bore 18 with its diameter, into which the ring element 26 of the compensating clutch 19 is inserted with its drivers 30 which engage in the radial slot of the shaft journal 8. The axially opposite drivers 31 engage positively in the slot 20 on the end face of the drive shaft 14. It can also be seen in FIG. 3a that the differential coupling 19 has a bore 32 in the axial direction, which has a radial step 33 in the ring element 26. The connecting tube 23 is inserted through the bore 32 of the compensating coupling 19 into the central axial bore 18 of the shaft journal 8 or 21 of the drive shaft 14 in a sealing manner (radial sealing rings 22), the insertion length being limited by the radial step of the axial bore 18.

For captive fastening of the compensating coupling 19 to the shaft journal 8, the connecting tube 23 has, on the one hand, approximately in its longitudinal center an annular shoulder (collar) 34, the outer diameter of which is somewhat larger than the smaller diameter of the bore 32 on the radial step 33. On the other hand, a groove is inserted at the end of the connecting tube 23 into which a spring ring 35 is loosely inserted, which can be clipped into the radial groove 36 of the axial bore 18 of the shaft journal 8. Through the connecting tube 23, the coupling intermediate piece 19 is thus fixed on the shaft journal 8 and has a predeterminable axial mobility.

3b shows a modified constructive solution in which the lubricating oil is injected as a free jet into the longitudinal bore 18 in the shaft journal 8. In this case, a short tube 23.1, which is funnel-shaped at the inlet in order to catch the oil jet emerging from the nozzle 37 at an axial distance, is firmly pressed into the shaft journal 8 (press fit). The annular shoulder 34.1 at the inlet of the tube 23.1 also has the previously described function to cooperate with the step 33 of the bore 32 in the compensating coupling 19 and to fix it captively, but with a definable axial play on the shaft journal 8.

In an advantageous embodiment of the connecting tube 23 or 23.1, this can be made of, in particular, thermoplastic and can be clipped into the radial groove 36 of the axial bore 18 in the shaft journal.

The solution according to FIG. 3b is preferred if the lubricating oil is supplied in excess from the bore 21 of the drive shaft 14, since the oil not taken up by the tube 23.1 can freely flow off and flow back into the oil sump of the engine. At low speeds and low oil delivery, however, the air entrained by the oil jet into the funnel-shaped extension of the tube 23.1 by means of an injector action ensures that a pressure of approx. 1 is always in the axial bore 18 of the rotor 9 and thus also in the wing root spaces 16 of the pump bar prevails.

Figures 4a to 4c show the compensating coupling 19 in the top and side view and in axial section according to the preceding description.

REFERENCE SIGN LISTING

• 1 pump housing
• 2 lids
• 3 intake manifolds
• 4 screws
• 5 turn
• 6 case back
• 7 bearing eye
• 8 shaft journals, rotor shaft
• 9 rotor
• 10 wings
• 11 axial bore, recess
• 12 centering flange
• 13 housing of the internal combustion engine
• 14 camshaft, drive shaft, driving shaft
• 15 Radial bore of the rotor under the wing footwell
• 16 wing footwell
• 17 coupling pin
• 18 centric axial bore
• 19 compensating coupling, intermediate piece
• 20 slot
• 21 Axial bore of the camshaft, oil feed channel 22 Radial seal
• 23 connecting pipe, pipe
• 23.1 Pipe with nozzle inlet
• 24 nozzle
• 25 Expansion of the central axial bore in the shaft journal
• 26 ring element
• 27 ring channel
• 28 outlet kidney
• 29 relief bore
• 30 driver, tooth
• 31 driver, tooth
• 32 hole
• 33 radial stage
• 34 ring shoulder (Fig. 3a), collar
• 34.1 ring shoulder (Fig. 3b), collar
• 35 spring washer
• 36 radial groove

Claims (7)

1. Rotary vane vacuum pump, in particular for servosystems, such as servo brakes or the like in internal combustion engines, comprising a rotor (9) mounted excentrically in a pump housing (1) and in which at least one pair of vanes (10) is guided in slots, wherein the rotor (9) is driven by a driving shaft (14) via a coupling (19) and wherein the coupling is a connecting piece in the form of a flexible coupling and is provided with coupling teeth (30, 31), said connecting piece being in positive axial engagement with the rotor shaft (8) at one side and with the driving shaft (14) at the other side, characterised in that the connecting piece has a bore (32), that a pin provided with a shoulder (34) passes via its free end through the connecting piece (19), that the pin can be clamped, preferably clipped, via its free end into a corresponding bore (18) in the rotor shaft (8), and that the shoulder is larger than the bore in the connecting piece (19).

2. Pump according to claim 1, characterised in that the connecting piece (19) is a circular cylindrical member having radial teeth, that the rotor shaft (8) has a circular cylindrical recess (25) at its front end, the cylindrical wall of which has radial slots, wherein the connecting piece (19) is fitted, with play, into the cylindrical recess (25) and the radial teeth (30) are fitted, with play, into the radial slots.

3. Rotary vane vacuum pump according to claim 2, characterised in that the connecting piece (19) has teeth (31) on its free front face, said teeth (31) engaging a radial slot (20) in the driving shaft (14).

4. Rotary vane vacuum pump according to claim 3, characterised in that the connecting piece (19) has a central stepped bore (32), the smaller diameter of which is greater than the external diameter of the pin, but smaller than the external diameter of the shoulder (34) provided on the pin.

5. Rotary vane vacuum pump according to one of claims 1 to 4, characterised in that the pin is a hollow central pipe (23) which is aligned with the oil feed bore (21) in the driving shaft (14).

6. Rotary vane vacuum pump according to claim 5, characterised in that the pin is an oil feed pipe (23) which projects into the driving shaft (14) and connects the central oil feed duct (21) in the interior of the driving shaft (14) with a central oil feed duct (18) in the interior of the rotor shaft (8).

7. Rotary vane vacuum pump according to claim 6, characterised in that the oil feed pipe (23) is sealed off from the rotor (9) and the driving shaft (14) by means of sealings (22).

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