GB1593989A

GB1593989A - Pump drive coupling

Info

Publication number: GB1593989A
Application number: GB5113777A
Authority: GB
Original assignee: Barmag Barmer Maschinenfabrik AG
Current assignee: Oerlikon Barmag AG
Priority date: 1976-12-08
Filing date: 1977-12-08
Publication date: 1981-07-22
Also published as: FR2373694B3; IT1090669B; FR2373694A1

Description

(54) PUMP DRIVE COUPLING (71) We, BARMAG BARMER MASCHINENFABRIK AKTIENGESELL SCHAFT, a body corporate organised under the laws of the Federal Republic of Germany, of Remscheid-Lennep, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to a pump, for example, a vacuum pump.

Vacuum pumps are needed for evacuating brake power assistance units, particularly in motor vehicles with diesel engines. The vacuum pumps, which are often vane pumps, are frequently flanged on to the engine of the vehicle for this purpose and coupled to a suitable drive mechanism, for example the drive shaft of the injection pump. A shaft which is driven via a toothed belt or a chain by the crank shaft of the engine of the motor vehicle can also be used as the drive mechanisms.

An object of the invention is to provide a coupling for pumps, which is capable of compensating a mis-match caused by normal tolerances, errors in positioning and a possible mis-match in the length of the shaft caused during production. The coupling is preferably simple in structure, requires little space and is inexpensive. The pump is also preferably adapted for rapid and safe installation in and removal from positions which are difficult to reach in restricted spaces. In addition, the coupling is desirably capable of functioning properly at temperatures of from 80"C up to about 140"C.

According to the invention there is provided a pump having a pump shaft, drive, shaft, and a coupling member arranged between the pump shaft and the drive shaft, the coupling member having two substantially parallel mounting planes in which it is respectively coupled to the pump shaft and the drive shaft, the coupling to one shaft being fixed and to the other shaft being movable.

The invention makes it possible to ensure that the torque is transferred to the pump without interruptions under the prescribed operating conditions with the required degree of reliability. this is particularly important when the pump is being used in a brake power assistance unit in a motor vehicle. Because the coupling member used in the invention has a simple structure, it can be very strong but inexpensive. It requires only a small amount of space both in its axial and in its radial directions. The coupling member compensates the mismatch and possible errors in position and mis-match of the shaft length caused by the usual tolerances, without being subjected to excessive stresses.

The coupling member may be connected positively or non-positively to the pump shaft. A positive connection is one in which the shape of the parts being connected keeps them together, whereas a nonpositive connection is one in which this is not so, for example a frictional connection.

Advantageously a leaf spring is used for the coupling which is bent in one plane. This promotes inexpensive production of the leaf-springs in large numbers.

In the accompanying drawings: Fig. 1 is a partial longitudinal section of a vacuum vane pump with coupling member used in the invention Fig. 2 shows a modification of the connection between the end of the pump shaft and the coupling member; Fig. 3 shows another means for connecting the pump shaft to its drive shaft; Fig. 4 is a detail from Fig. 3 viewed in the direction of the arrow A; Fig. 5 is a detail of a means for fixing the coupling member similar to the one shown in Fig. 3; Fig. 6 shows another means for connecting the pump shaft to its drive shaft; Fig. 7 is a detail from Fig. 6, viewed in the direction of the arrow B; Fig. 8 shows a variation of the vacuum vane pump (Partially in section) with the compensating coupling member; Fig. 9 is another detail of the pump drive with another embodiment of the coupling member used in the invention; Fig. 10 shows a coupling shackle used in Fig. 9; Fig. 11 and 1 Ia show embodiments of a catch; Fig. 12 and 12a show components for aiding assembly of the coupling member of Fig. 9.

Fig. 1 is a cross-section through the drive mechanism of a pump according to the invention. A vacuum vane pump 1 with a lubricating oil inlet into the pump shaft has been used as an example in this case, but the pump could be of some other type.

The vane pump 1 is secured by screws on to a suitable drive motor of which only the fixing flange 2 is shown here. The pump has a drive shaft 3 which is located in the fixing flange 2. The shaft is driven by a crank shaft via a timing chain (not shown) when used as a vacuum pump for a brake power assistance unit in a motor vehicle driven by a diesel engine.

The pump 1 has a hollow pump shaft 4 defining an axial passage 9, the shaft being rotatably mounted by means of ball bearings 5 in the housing. A pump rotor 6 is fixed on the hollow shaft 4 and receives vanes 7 which are slidable in the radial direction.

The right-hand end of the hollow shaft 4 is provided with an end wall in the form of a flange 8 having an aperture 10 arranged coaxially with respect to the axial passage 9 of the hollow shaft 4.

A leaf-spring 12 acting as a compensating coupling member is fixed to the flange 8 of the hollow shaft 4 by means of rivets 11. The leaf-spring has two S-shaped bent sections 12a, a straight central section 14 and two straight end sections 14, the planes in which the sections 13 and 14 lie being parallel. This design of leaf spring is reliable, durable and inexpensive.

The central straight section 13 has an aperture 15 disposed coaxially to the aperture 10 in the end wall 8.

The end of the pump drive shaft 3 has a flange 16 mounted thereon. Clinch bolts 18 fixed on the straight end sections 14 of the leaf spring 12 are inserted in passages 17 in the flange 16 with a sliding fit.

The pump drive shaft 3 is hollow and receives a hollow mandrel 20 the axial passage 21 of which communicates with a system for lubricating the engine.

Lubricating oil leaving the passage 21 in a free jet passes through the apertures 15 and 10 and enters the axial passage in the hollow shaft 4. From here, it passes through radial passages, (not shown) through the wall of the hollow shaft 4 and the rotor 6 as well as axiallv from the hollow shaft 4 and through the ball bearing 5 onto the conventional lubrication points of a vacuum vane pump.

The torque to be transferred is transmitted to the leaf-spring 12 via the bolts 18 and thence transmitted to the rotor of the vacuum vane pump via the rivets 11 and the flange 8. The axial movability of the bolts 18 in the passages 17 allows the vacuum pump to even be inserted in and removed from narrow engine housings. Two separate leafsprings each having an S-shaped bent section may be provided instead of the leafspring 12 shown in Fig. 1. In this case, a straight arm of the S-shaped section 12a of each leaf-spring would be connected to the flange 8 of the hollow shaft 4 instead of having a central section. The radially inwardly directed straight arms of the Sshaped bent section 12a of the leaf-spring are only long enough for the passage 15 not to be closed. Depending upon the coupling mis-match between the pump shaft and drive mechanism, the leaf springs 12 may be subjected at times to bending and at other times to torsion or even be subjected to a compound stress with each rotation.

In a modification of the embodiment of Fig. 1, shown in Fig. 2, the flange 8 is produced separately from the hollow shaft 4, so as economise in material, and hub 22 thereof is inserted with a driving fit into the hollow shaft 4. The hollow shaft 4 may be produced, for example, from a relatively soft sintered metal and the flange 8 from steel.

Another means of connecting the leafspring 12 to the hollow shaft 4 is shown in Figs. 3 and 4. A relatively thick end wall 23 of the hollow shaft 4 is provided with flats 25 at the periphery at two positions which are disposed at 180 to each other. The leafspring 12 is widened in its central region and has a central passage 26. A catch 24 is fixed on the leaf-spring 12 by means of rivets 11.

The catch 24 is provided with a longitudinal slit which is sufficiently wide for the catch 24 to be pushed with a sliding fit on to the flats 25 of the end wall 23. The length of the longitudinal slit is sufficient for the catch to also be able to slide radially with respect to the pump shaft on the flats 25. The ends of the leaf-springs 14 are fixed to the flange 16 by screws 27 so that in this embodiment, in contrast to that of Fig. 1, axial movability is provided at the join between the pump shaft and the leaf-spring 12. As well as simplifying assembly of the pump, the sliding fit is also advantageous with regard to the stress on the leaf-spring 12. It is normally only subjected to bending stresses.

In a modification of Figs. 3 and 4 the screws 27 are replaced by clinch bolts 18 in this case. In addition, the width of the slit shaped recess in the catch 24 is selected to be such that the catch is arranged with a driving fit on the flats 25 of the end face 23.

In Fig. 5, the hollow shaft is produced from a smooth length of tube without a special end wall. The right hand end of the length of tube is milled to leave dia metrically opposed catch brackets 36 from the wall of the tube. The catch 37 is provided with a longitudinal slit which enables the catch to be pushed with driving fit or sliding fit on to the brackets 36 as in Fig. 3 and 4. The leaf-spring 12 is of equal width over its entire length and has a passage 38 in its straight central section 13, the diameter of which is such that although the jet of lubricating oil can enter the passage 9 of the hollow shaft 4 without obstruction the passage 9 of the hollow shaft 4 is sealed by the leaf-spring 12 sufficiently to prevent the oil from flowing out of the hollow shaft 4. This embodiment is particularly simple and inexpensive.

Fig. 6 and 7 show another embodiment in which the ends 14 of the leaf-spring are fixed by screws 27 on the flange 16. The straight central section 13 of the leaf-spring 12 supports a catch ring 28 with internal teeth which engages in a section 29 of the hollow shaft 4 having external teeth and is axially movable on this section. The straight central section 13 of the leaf-spring 12 is correspondingly widened and has a relatively large central passage 26, as in Fig. 4.

Tolerances in the axial dimensions of the inserts are substantially compensated by the teeth.

In Fig. 8, in contrast to the embodiments described with reference to Figs. 1 to 7, the shaft and rotor are produced from one piece. Sliding bearing 30 and 31 are used instead of a ball bearing. The bush of the bearing 31 is formed of steel and is pressed with a driving fit into the axial passage 9.

The central straight section 13 of the leafspring 12 is held in the axial direction by a screw 32. Torque is transferred from the leaf-spring 12 to the pump shaft mainly via a rivet 33. The screw 32 has a central passage 34 through which the lubricating oil enters the pump shaft. The lubricating oil is conveyed by centrifugal force through radial passages (not shown) in the wall of the axial passage 9 and through the rotor body to the conventional lubrication points on the vacuum pump. Alternatively, the screw 32 may be dispensed with if screws or other fixing elements which are able to take up axial forces are used instead of the rivets 33.

The ends of the leaf-spring 14 are retained in axially movable fashion on the flange 16 as described with reference to Fig. 1.

Figs. 9 to I 1 show a pump with a coupling member formed of rigid elements. This coupling member is particularly suitable when there are no errors in positioning, so that a leaf-spring is not required.

In this case, the coupling member consists of a catch 44 with a shackle 40 which is fixed to the flange 16 by screws. The shackle 40 is bent from flat material and has parallel, planar fixing portions 40.1 and 40.2. A slot 41 running in the longitudinal direction of the shackle 40 (see also Fig. 10) is punched in the forward fixing plane 40.1 and widens to a passage 42 in the centre.

Axially aligned guide pins 43 of the catch 44 engage in the slot 41. The catch 44 (Fig.

11) is a plate produced from sintered metal which also has a radially aligned slot 45 which widens to a passage 46 in the centre.

The guide pins 43 and the slots 45 are so arranged that the slot 45 may be moved perpendicularly to the slot 41 when the coupling member is mounted.

The guide pins of the hollow pump shaft 4 engage in the slot 45 of the catch 44. The hollow mandrel 20 of the lubricating oil inlet projects through the passages 42 and 46 into the hollow pump shaft 4. The lubricant is supplied through the drive shaft 3 from the lubricating system of the engine, as already described with reference to Fig. 1.

On account of the two cross-over slots 41 and 45 and the guide pins of the catch and the pump shaft which slide therein, it is possible to compensate a mis-match of the drive shaft to the pump shaft lying within normal tolerances. Thus, the passages 42 and 46 ensure that despite any mis-match of the hollow mandrel 20, the lubricant inlet is not damaged or curved during operation.

The component shown in Fig. 12 or that shown in Fig. 12a may be used to prevent the catch 44 from falling from the shackle 40 to the fixing flange 2 when the pump 1 is being assembled in the case of a vertical arrangement of the shackle 40.

Fig. 12 shows a rivet 47 which is preferably formed of a plastics material. The rivet has barbs for securing it in pocket holes 48 in the guide pins 43. The head of the rivet is larger than the width of the slot 41 in the shackle 40 so as to prevent the catch 44 from falling out.

The component shown in Fig. 12a is a plastics ring 49 with two passages. Instead of the passage 48, pins are arranged on the ring 49 for receiving the catch 44. l he ring 49 has the advantage that the ring is taken up by the lubricant pipe 20 when the pins are broken off during operation. This prevents the coupling member or the lubricant pipe from being damaged. The components mentioned above may remain in the pump after assembly without causing any damage.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

screws 27 are replaced by clinch bolts 18 in this case. In addition, the width of the slit shaped recess in the catch 24 is selected to be such that the catch is arranged with a driving fit on the flats 25 of the end face 23.

In Fig. 5, the hollow shaft is produced from a smooth length of tube without a special end wall. The right hand end of the length of tube is milled to leave dia metrically opposed catch brackets 36 from the wall of the tube. The catch 37 is provided with a longitudinal slit which enables the catch to be pushed with driving fit or sliding fit on to the brackets 36 as in Fig. 3 and 4. The leaf-spring 12 is of equal width over its entire length and has a passage 38 in its straight central section 13, the diameter of which is such that although the jet of lubricating oil can enter the passage 9 of the hollow shaft 4 without obstruction the passage 9 of the hollow shaft 4 is sealed by the leaf-spring 12 sufficiently to prevent the oil from flowing out of the hollow shaft 4. This embodiment is particularly simple and inexpensive.

Fig. 6 and 7 show another embodiment in which the ends 14 of the leaf-spring are fixed by screws 27 on the flange 16. The straight central section 13 of the leaf-spring

12 supports a catch ring 28 with internal teeth which engages in a section 29 of the hollow shaft 4 having external teeth and is axially movable on this section. The straight central section 13 of the leaf-spring 12 is correspondingly widened and has a relatively large central passage 26, as in Fig. 4.

Tolerances in the axial dimensions of the inserts are substantially compensated by the teeth.

In Fig. 8, in contrast to the embodiments described with reference to Figs. 1 to 7, the shaft and rotor are produced from one piece. Sliding bearing 30 and 31 are used instead of a ball bearing. The bush of the bearing 31 is formed of steel and is pressed with a driving fit into the axial passage 9.

The central straight section 13 of the leafspring 12 is held in the axial direction by a screw 32. Torque is transferred from the leaf-spring 12 to the pump shaft mainly via a rivet 33. The screw 32 has a central passage 34 through which the lubricating oil enters the pump shaft. The lubricating oil is conveyed by centrifugal force through radial passages (not shown) in the wall of the axial passage 9 and through the rotor body to the conventional lubrication points on the vacuum pump. Alternatively, the screw 32 may be dispensed with if screws or other fixing elements which are able to take up axial forces are used instead of the rivets 33.

The ends of the leaf-spring 14 are retained in axially movable fashion on the flange 16 as described with reference to Fig. 1.

Figs. 9 to I 1 show a pump with a coupling member formed of rigid elements. This coupling member is particularly suitable when there are no errors in positioning, so that a leaf-spring is not required.

In this case, the coupling member consists of a catch 44 with a shackle 40 which is fixed to the flange 16 by screws. The shackle 40 is bent from flat material and has parallel, planar fixing portions 40.1 and 40.2. A slot 41 running in the longitudinal direction of the shackle 40 (see also Fig. 10) is punched in the forward fixing plane 40.1 and widens to a passage 42 in the centre.

Axially aligned guide pins 43 of the catch 44 engage in the slot 41. The catch 44 (Fig.

11) is a plate produced from sintered metal which also has a radially aligned slot 45 which widens to a passage 46 in the centre.

The guide pins 43 and the slots 45 are so arranged that the slot 45 may be moved perpendicularly to the slot 41 when the coupling member is mounted.

The guide pins of the hollow pump shaft 4 engage in the slot 45 of the catch 44. The hollow mandrel 20 of the lubricating oil inlet projects through the passages 42 and 46 into the hollow pump shaft 4. The lubricant is supplied through the drive shaft 3 from the lubricating system of the engine, as already described with reference to Fig. 1.

On account of the two cross-over slots 41 and 45 and the guide pins of the catch and the pump shaft which slide therein, it is possible to compensate a mis-match of the drive shaft to the pump shaft lying within normal tolerances. Thus, the passages 42 and 46 ensure that despite any mis-match of the hollow mandrel 20, the lubricant inlet is not damaged or curved during operation.

The component shown in Fig. 12 or that shown in Fig. 12a may be used to prevent the catch 44 from falling from the shackle 40 to the fixing flange 2 when the pump 1 is being assembled in the case of a vertical arrangement of the shackle 40.

Fig. 12 shows a rivet 47 which is preferably formed of a plastics material. The rivet has barbs for securing it in pocket holes 48 in the guide pins 43. The head of the rivet is larger than the width of the slot 41 in the shackle 40 so as to prevent the catch 44 from falling out.

The component shown in Fig. 12a is a plastics ring 49 with two passages. Instead of the passage 48, pins are arranged on the ring 49 for receiving the catch 44. l he ring 49 has the advantage that the ring is taken up by the lubricant pipe 20 when the pins are broken off during operation. This prevents the coupling member or the lubricant pipe from being damaged. The components mentioned above may remain in the pump after assembly without causing any damage.

shaft, and a coupling member arranged

between the pump shaft and the drive shaft, the coupling member having two substantially parallal mounting planes in which it is respectively coupled to the pump shaft and the drive shaft, the coupling to one shaft being fixed and to the other shaft being movable.
2. A pump according to claim 1, wherein the coupling member comprises a leaf spring.
3. A pump according to claim 2, wherein the coupling member comprises a catch arranged on the pump shaft and the spring.
4. A pump according to claim 3, wherein the coupling member is positively connected to the pump shaft.
5. A pump according to claim 2 or 3, wherein the coupling member is nonpositively connected to the pump shaft.
6. A pump according to any one of claims 2 to 5, wherein in that the leaf-spring is bent only in one plane.
7. A pump according to any one of claims 2 to 6, wherein the coupling member comprises a leaf-spring with two S-shaped sections which are joined together at one end by a straight section, both the straight section and the two other end regions lying in parallel planes at any time.
8. A pump according to claim 7, wherein the said straight section of the leaf-spring is connected to the pump shaft.
9. A pump according to any one of claims 2 to 6, wherein the coupling member comprises at least two leaf springs each having an S-shaped section.
10. A pump according to any one of claims 2 to 9, wherein the junction between the coupling member and the pump shaft permits relative axial movement.
11. A pump according to any one of claims 2 to 10, wherein the pump shaft is hollow and the leaf spring has an opening arranged axially to the hollow shaft.
12. A pump according to claim 1, wherein the pump shaft comprises a length of tube whose driven end is formed with axial projections which are connected to a longitudinal slot in a catch so as to allow torque transfer, a leaf spring being fixed to the catch and covering a passage within the pump shaft, the leaf spring having an aperture therein the diameter of which is small in relation to the diameter of the passage in the pump shaft.
13. A pump according to claim 1, wherein the coupling member comprises a shackle and a catch, the shackle having a trapezoidal longitudinal section, the catch having two guide pins arranged diametrically by means of which it is held in a slot in the shackle, and the catch having another slot perpendicular to that of the shackle.
14. A pump according to claim 13, wherein the shackle is produced from flat material by bending.
15. A pump according to claim 13 or 14, wherein the catch is of sintered metal.
16. A pump according to any one of claims 13 to 15, wherein a passage is arranged in the middle of each said slot, the diameter of which passage is larger than the width of the respective slot.
17. A pump according to any one of claims 13 to 16, wherein the guide pins have pocket holes therein.
18. A pump according to claim 17, wherein rivets whose heads are greater than the width of the slots in the shackle are inserted in the said pocket holes.
19. A pump according to claim 17, wherein the pins of a ring are inserted in the said pocket holes.
20. A pump according to any one of claims 13 to 19, wherein the guide pins lie in a different plane from the slot in the catch.
21. A pump according to any preceding claim, which is a vacuum vane pump.
22. A pump substantially as herein described with reference to any one of the embodiments shown in the accompanying drawings.
23. A motor vehicle having a power assistance unit for providing power assistance to the brakes, provided with a pump as claimed in any preceding claim for evacuating the said unit.