DE102007056316A1 - Pump, especially vane-cell vacuum pump for vehicle brake servo systems, has switching device which acts upon sprag and even during rotation of drive in working direction of pump effects decoupling of rotor from drive - Google Patents

Abstract

The pump, especially a vane-cell vacuum pump for vehicle brake servo systems, with a rotor (7) which can be coupled to the drive (11) via a sprag (37) and a freewheel (9), has a switching device (41) which acts upon the sprag and even during rotation of the drive in the working direction of the pump presses it against the force of a spring into its second functioning position, so that the rotor is decoupled from the drive.

Description

The The invention relates to a pump, in particular a vane-type vacuum pump, for motor vehicle brake booster systems according to the generic term of claim 1.

pump the type mentioned here are known. They serve one Negative pressure for Automotive brake booster systems to disposal to provide and have a rotor, which has a freewheel of a Drive in the working direction of the pump is set in rotation. The freewheel has an inner ring coupled to the rotor and a this overarching coupled to the drive outer ring on. On the outside surface of the Inner rings are - in Cross-section seen - wedge-shaped recesses provided to receive the spring-loaded clamping body. The depth of the Wedges is chosen that they absorb the clamping body in their deepest areas and in their Outlet area press this against the outer ring. Will the outer ring rotated in the direction of the pump, the clamp body between his inner surface and the inner ring clamped so that the inner ring synchronously with the outer ring rotates. Rotates the outer ring in the opposite direction, decoupled the freewheel, because of clamping bodies in an area of wedge-shaped Recess is introduced, in the outer ring no forces on the Transfer inner ring become. Such a coupling thus ensures that the rotor is not driven counter to the working direction of the pump, if the drive unintentionally runs backwards. Will one such pump used in a motor vehicle, this is driven constantly, what an increased Energy consumption and also to reduce the maximum output of the Drive the vehicle, in particular the internal combustion engine leads.

task The invention therefore is to provide a pump which has this disadvantage does not have.

to solution this object, a pump is proposed which the claim 1 features includes. It has a rotor, which has a known freewheel of the type described above with a drive can be coupled. The freewheel thus has at least one clamping body, the upon rotation of the drive in the direction of the pump assumes a first functional position and the drive with the rotor the pump couples. With a rotation of the drive in opposite Direction takes the at least one clamp body a second functional position a, a decoupling position, so that the drive is decoupled from the rotor, So this does not rotate. The pump is characterized by that a switching device is provided, the targeted decoupling allows the rotor of the drive. It acts on the at least one clamp body that this, too when the drive rotates in the working direction of the pump, contrary the power of the associated Spring in its second functional position, the decoupling position, packed and the rotor is decoupled from the drive. The pump is loaded So the drive no further.

A preferred pump is characterized by the fact that at least a switching element part of a cage is that form-fitting coupled with an inner ring of the freewheel and on the at least a clamp body can act.

at Another preferred pump is provided that the switching device a hydraulically operated Piston which is displaceable in the direction of the cage to this decelerate. This realization of the switching device is therefore very cheap, because in any case an oil supply is provided in connection with the pump, then the operation the piston can be used.

at Another preferred pump is provided that this one Having space formed as a pressure chamber, with the piston interacts. This embodiment allows one very compact design.

A another embodiment The pump is preferred because a coupling between the Cage of Switching device and the inner ring of the freewheel a return spring includes. This serves to possibly press the rotor against a braking surface, so that a turning back of the Rotor is avoided.

at a particularly preferred embodiment the pump is an oil supply provided, which is designed so that when interrupting the drive the rotor is also interrupted.

Further Embodiments of the pump will become apparent from the dependent claims.

The Pump will be explained in more detail below with reference to the drawing. Show it:

1 a schematic diagram of the pump in longitudinal section and

2 a cross section through the freewheel of the pump according to 1

From the schematic diagram according to 1 is a pump 1 with a pump room 3 enclosing housing 5 , with a rotor 7 , a freewheel 9 and with a drive 11 seen from the here only a stub shaft 13 is shown. The design of the drive 11 is for the functioning of the pump 1 and the freewheel 9 not significant. The pump room 3 takes, for example, a wing of a vane pump, not shown here, of the rotor 7 is rotary drivable. The pump 1 serves, for example, to generate negative pressure in a motor vehicle brake booster system.

The housing 5 has a warehouse approach 15 on, the rotor 7 embraces. This lies with areas of its peripheral surface 17 on areas of the inner surface 19 of the stock approach 15 so that a storage area is created. The pump 1 can from an oil pump 21 over a line 23 and an opening 25 in the warehouse approach 15 be supplied with oil, so on the one hand, the bearing area between the rotor 7 and inner surface 19 of the stock approach 15 and on the other hand, the pump room 3 be lubricated. This will be discussed in more detail below.

At the pump room 3 opposite end 27 of the rotor 7 is the freewheel 9 provided, one rotatably with the rotor 7 coupled inner ring 29 and an outer ring surrounding this outside 31 includes, the part of the drive 11 is and the end 27 of the rotor 7 embracing bell 33 can have that with the outer ring 31 coupled or integrally formed therewith. The bell 33 is with the stub shaft 13 coupled, preferably integrally formed therewith. It is, moreover, about a suitable camp 35 , which is designed for example as a deep groove ball bearing, on the rotor 7 stored with low friction. In 1 is still one of the freewheel 9 associated clamping body 37 recognizable, in a recess 39 in the peripheral surface of the inner ring 29 is housed and both with the inner ring 29 as well as with the outer ring 31 can be brought into engagement, depending on the operating state of the freewheel 9 ,

The pump 1 has a switching device 41 on, the at least one switching element 43 comprising, which on the at least one clamping body 37 of the freewheel 9 acts. It therefore attacks the freewheel 9 especially in the inner ring 29 what, based on 2 will be explained in more detail. The switching element is part of a cage 45 , who also belongs to the switching device 41 heard and the rotor 7 surrounds. He can with the rotor 7 run along. The switching device 41 but has a braking device that rotatably with the bearing lug 15 is coupled to the cage 45 act and slow it down. In this case, there is a relative rotation between the cage 45 and the rotor 7 and the attached inner ring 29 instead of.

The braking device comprises a piston 47 , which is annular and the rotor 7 embraces. A part of the piston 47 lies together with the rotor 7 inside the bearing approach 15 that of a sealing plate 49 at his the pump room 3 opposite end is completed. The sealing plate 49 can be made of metal. The one in the storage approach 15 lying area of the piston 47 is in a room 51 arranged over a hole 53 with a line 55 connected is. The piston 47 acts with a return spring 57 on the one hand, on the sealing plate 49 and on the other hand on the piston 47 , here about one in the peripheral surface of the piston 47 introduced ring 58 supported and designed as a helical spring, which is the piston 47 surrounds. This is thus acted upon by a biasing force, the piston in the direction of the axis of rotation 59 to the left in the room 51 shifted, so that this assumes its first functional position, in which he the cage 45 not touched or only with a small contact force. The piston 47 is suitably, for example via a projection 61 the sealing plate 49 placed in a recess of the piston 47 engages, rotatably on the housing 5 the pump 1 , here at the stock approach 15 held.

Will be in the room 51 a medium, such as oil introduced, so in this an overpressure is built up. This is the piston 47 close to the outer surface of the rotor 7 at. By the way, the sealing plate seals 49 the room 51 outwards. At an overpressure in the room 51 becomes the piston 47 against the force of the return spring 57 from the in 1 displaced position shown to the right in a second functional position in which he with his front side on the surface facing him of the cage 45 is applied and thus builds a friction force, the pressure in the room 51 and the counterforce of the return spring 57 depends.

Part of the switching device 41 is also a valve unit 63 which is a 4/2-way valve 65 has, which is merely indicated here. It is via a control line 67 controlled by the pump 1 generated pressure, in particular so the negative pressure for one with the pump 1 connected motor vehicle brake booster system detected.

In a first functional position of the 4/2-way valve 65 is the lead 23 with the pump 21 connected, the line 55 with a tank 69 , In this illustrated functional position of the 4/2-way valve 65 the storage area is between rotor 7 and bearing approach 15 from the oil pump 21 over the line 23 and the opening 25 supplied with oil, as well as the pump room 3 , At the same time is the room 51 over the hole 53 and the line 55 with the tank 69 connected, so without pressure. The return spring 57 So, as in 1 shown, the piston 47 to the left in the unpressurized room 51 shift into it.

It is determined that the pump 1 the desired pressure, so here a desired negative pressure in the motor vehicle brake booster system, has generated, is via the control line 67 the 4/2-way valve 65 is switched so that, as from the switching symbol in 1 apparent, the oil supply to the pump 1 is interrupted by the line 23 in connection with the tank 69 is brought. At the same time the oil pump 21 over the line 55 and the hole 53 with the room 51 connected so that a medium is fed here, in particular here so a hydraulic oil, and an overpressure in the room 51 is built. This causes the piston 47 against the force of the return spring 57 opposite the rotor 7 and the stock approach 15 to the right in the direction of the axis of rotation 59 is relocated. He presses therefore with his front side against in 1 left-facing surface of the cage 45 so that it is decelerated because of the piston 47 rotatably in the bearing approach 15 is held. Then it rotates with the rotor 7 non-rotatably connected inner ring 29 due to its inertia somewhat opposite the cage 45 which will be discussed in more detail below.

1 Finally shows that the switching device 41 a return spring F has, on the one hand on the inner ring 29 and on the other hand on the inner ring 29 facing side of the cage 45 supported. Out 1 it can be seen that the cage 45 over the piston 47 on the pressure plate 49 supported. The biased return spring F thus exerts on the inner ring 29 one in 1 rightward force, which causes one in the pump room 3 lying area of the rotor 7 is pressed against a braking surface B of the housing.

2 shows a cross section through the freewheel 9 the pump 1 , The same parts are provided with the same reference numerals, so far as the description to 1 is referenced. The representation is opposite to in 1 slightly enlarged.

Out 2 So it's the pump 1 with her case 5 and the associated inventory approach 15 seen. This is the one with the rotor 7 non-rotatably coupled inner ring 29 of the freewheel 9 that of the outer ring 31 surrounded, the part of the drive 11 is. Clearly visible is also the at least one clamping body 37 in one in the circumferential area 71 of the inner ring 29 introduced wedge-shaped recess 39 is housed. This is characterized by the fact that - measured from the peripheral surface 71 - becomes deeper and deeper in the clockwise direction, the depth being the size of the clamp body 37 is adjusted so that this, without the inner surface of the outer ring 31 to touch, in the area of the lowest point of the recess 39 can be accommodated. In the embodiment of the pump shown here 1 is provided that the freewheel 9 Has four identical clamp body, so that the following description is based exclusively on one of these clamping body. In addition, the clamping body receiving recesses 39 and the rest in connection with the clamp body 37 identical elements.

Each of the clamp bodies 37 is from a spring 73 subjected to a biasing force, this counterclockwise within the recess 39 pushes in the flatter area, so that the clamping body 37 on the one hand with the bottom of the recess 39 and on the other hand with the inner surface of the outer ring 31 comes into contact. The clamp body 37 can be designed as a ball, but preferably also, as here, as a cylindrical element whose longitudinal axis is in 2 extends into the picture plane.

On the pen 73 opposite side of each clamp body 37 is the switching element 43 arranged, for example, as perpendicular to the image plane of 2 extending pin is formed in the recess 39 protrudes and with the clamp body 37 can engage, while having such a small outer diameter that this in the left of the clamp body 37 given free space in the recess 39 can be accommodated without causing a coupling between inner and outer ring.

The switching element 43 is how based on 1 explained with the cage 45 the switching device 41 connected or integrally formed with this and engages in the inner ring 29 one. So it turns when no forces on the cage 45 act synchronously with the inner ring 29 ,

Will, as by an arrow 75 indicated, the outer ring 31 in the working direction of the pump 1 turned counterclockwise, so jammed the clamp body 37 that with a biasing force of the spring 73 is applied between the inner surface of the outer ring 31 and the bottom of the recess 39 so one into the outer ring 31 initiated torque over the freewheel 9 on the inner ring 29 and thus on the rotor 7 is transmitted.

The frictional forces of the clamp body 37 between the inner surface of the outer ring 31 and the bottom of the recess 39 are chosen so that the clamp body 37 when a limit torque is exceeded in the outer ring 31 is initiated, spin, so the pump 1 not overloaded.

Will drive the pump 1 So that's the outer ring 31 opposite to the arrow 75 indicated working direction of the pump 1 in rotation offset, so cause frictional forces between the inner surface of the outer ring 31 and the sprags 37 that these are against the force of the spring 73 clockwise inside the recess 39 be shifted and no friction forces on the inner ring 29 can transfer: The freewheel 9 is decoupled with it, causing damage to the pump 1 be avoided.

Below we assumed that the outer ring 31 in the direction of the arrow 75 indicated working direction of the pump 1 rotates counterclockwise and through the clamp body 37 the drive torque on the inner ring 29 and thus on the rotor 7 is transmitted. This creates the pump 1 a pressure, for example a vacuum for a motor vehicle brake booster system. In this operating state is the 4/2-way valve 65 in the in 1 position so that the oil pump 21 over the line 23 and the opening 25 Oil for lubrication of the pump 1 in the case 5 feeds. At the same time is the room 51 over the hole 53 and the line 55 with the tank 69 connected, thus pressureless. The return spring 57 shifts the piston 47 to the left, so this on the cage 45 no braking forces. Then the cage moves 45 synchronous with the inner ring 29 , and the switching elements 43 practice on the clamp body 37 no powers off.

Has the pump driven in this way 1 the desired pressure, so here constructed a certain negative pressure in a motor vehicle brake booster system, so a signal via the control line 67 to the valve unit 63 delivered so that the 4/2-way valve 65 switches. This will be over the line 23 and the hole 25 no more oil to the pump 1 delivered. The administration 23 is with the tank 69 connected. That's what the oil pump is for 21 over the line 55 and the hole 53 with the room 51 connected so that an overpressure is built up, which is the piston 47 against the force of the return spring 57 shifted to the right, so this a braking force on the cage 45 exercises. The pump 1 so that the rotor too 7 and the inner ring 29 , keep turning in the direction indicated by the arrow 75 indicated working direction, so that a relative rotation between the inner ring 29 and the braked cage. This causes the switching elements 43 in the recesses 39 a compressive force on the clamp body 37 - in 2 clockwise - exert, so that they no longer with the inner surface of the outer ring 31 engaged: This is the freewheel 9 despite the introduction of a torque in the outer ring 31 decoupled, so no further driving forces on the rotor 7 act and the pump 1 comes to a standstill.

So when the drive is running, so when introducing a torque in the outer ring 31 the freewheel 9 decoupled, the pump remains 1 Finally, there are no longer any negative pressure. By decoupling the drive is not charged further, which leads to energy savings.

Is the pump 1 has come to a halt, it must be ensured that they are not opposed by the arrow 75 indicated direction of rotation back, because this is when the cage 45 that would cause the freewheel 9 the drive again with the rotor 7 would couple.

Turning back the rotor 7 is prevented by the above-described return spring F, which is the rotor 7 presses against the braking surface B. After decoupling the freewheel 9 so comes the rotor 7 also with continuing outer ring 31 finally to a standstill. The braking forces prevent the pump 1 then unintentionally opposite to the arrow 75 indicated working direction back, ie clockwise.

On the return spring F can be omitted if the cage 45 through the piston 47 in the direction of the axis of rotation 59 so far to the right is shifted that the cage 45 at a facing this end face of the inner ring 29 abuts and exerts a braking force. If the return spring F is dispensed with, the frictional forces between the piston must be avoided 47 and the cage 45 be greater than the frictional forces between the cage 45 and the inner ring 29 ,

By adjusting the frictional forces or by using the return spring F ensures that the pump 1 when the freewheel 9 was once decoupled while the drive was running, what a einzi ger brake pulse on the cage 45 is enough, stops and is not contrary to the arrow 75 indicated working direction turns.

To restart the pump is via the control line 67 a signal to the valve unit 63 or at the 4/2-way valve 65 delivered, so this the room 51 again with the tank 69 combines. The piston 47 is then by the return spring 57 in the direction of the axis of rotation 59 shifted to the left, so the braking forces on the cage 45 be degraded and this free with the inner ring 29 is rotatable. The on the clamp body 37 acting springs 73 can because so are the switching elements 43 are freely movable, the clamp body 37 together with the switching elements 43 in 2 shift counterclockwise while keeping the cage 45 also turn counterclockwise. This allows the clamp body 37 with the inner surface of the outer ring 31 engage, which is still in the direction of the arrow 75 , ie in the working direction of the pump 1 , turns. The freewheel 9 coupled in this way again and the pump 1 is running. She turns in doing work tung.

In this case, the 4/2-way valve 65 at the same time, make sure the pump 1 from the oil pump 21 over the line 23 and the opening 25 oiled and lubricated with it.

1

pump

3

pump room

5

casing

7

rotor

9

freewheel

11

drive

13

stub shaft

15

bearing projection

19

palm

21

oil pump

23

management

25

opening

27

The End

29

inner ring

31

outer ring

33

Bell jar

35

camp

37

clamping bodies

39

recess

41

switching device

43

switching element

45

Cage

47

piston

49

sealing plate

51

room

53

drilling

55

management

57

Return spring

59

axis of rotation

61

head Start

63

valve unit

65

4.2 way valve

67

control line

69

tank

71

peripheral surface

73

feather

75

arrow

Claims (14)

Pump, in particular vane-type vacuum pump, for motor vehicle brake booster systems, having a rotor ( 7 ), which has at least one clamping body ( 37 ) and at least one spring ( 73 ) freewheel ( 9 ) with a drive ( 11 ) is coupled, wherein the at least one clamping body ( 37 ) upon rotation of the drive ( 11 ) in the working direction of the pump ( 1 ) occupies a first functional position and the drive ( 11 ) with the rotor ( 7 ) of the pump ( 1 ) and upon rotation of the drive ( 11 ) assumes a second functional position in the opposite direction and the drive ( 11 ) opposite the rotor ( 7 ) decoupled, characterized by a switching device ( 41 ), which on the at least one Klemmköper ( 37 ) and also with a rotation of the drive ( 11 ) in the working direction of the pump ( 1 ) against the force of the spring ( 73 ) in its second functional position, so that the rotor ( 7 ) of the output ( 11 ) is decoupled. Pump according to claim 1, characterized in that the switching device ( 41 ) at least one switching element ( 43 ), which on the at least one clamping body ( 37 ) and that the number of switching elements ( 43 ) the number of clamping bodies ( 37 ) corresponds. Pump according to claim 2, characterized in that the at least one switching element ( 43 ) Part of a cage ( 45 ), which is form-fitting with an inner ring ( 29 ) of the freewheel ( 9 ), and that the inner ring ( 29 ) for decoupling the drive ( 11 ) opposite the cage ( 45 ) in the working direction of the pump ( 1 ) is twisted. Pump according to claim 3, characterized by one on the cage ( 45 ) acting braking device which slows down when activated this, so that this relative to the further rotating inner ring ( 29 ) counter to the working direction of the pump ( 1 ) twisted. Pump according to claim 4, characterized in that the braking device has a - preferably in the direction of the axis of rotation ( 59 ) of the rotor ( 7 ) displaceable - piston ( 47 ) mounted on the cage ( 45 ) exerts a braking force. Pump according to claim 5, characterized in that the piston ( 47 ) - preferably against the force of a return spring ( 57 ) - hydraulically towards the cage ( 45 ) is displaceable. Pump according to claim 6, characterized in that it comprises a chamber (FIG. 51 ) connected to the piston ( 47 ) cooperates. Pump according to one of the preceding claims, characterized by a coupling between the cage ( 45 ) of the switching device ( 41 ) and the freewheel ( 9 ) associated inner ring ( 29 ), which faces the rotor ( 7 ) is rotationally fixed. Pump according to claim 8, characterized in that the coupling is a return spring (F). Pump according to claim 8, characterized in that the coupling to a first friction surface the inner ring ( 29 ) and one of the first friction surface facing second friction surface on the cage ( 45 ), wherein the friction forces of the coupling between the inner ring ( 29 ) and cage ( 45 ) are smaller than the braking forces of the cage ( 45 ) acting braking device. Pump according to one of the preceding claims, characterized in that the switching device ( 41 ) is switchable in response to the pressure in the automotive brake booster system. Pump according to claim 11, characterized in that the drive of the pump ( 1 ) is interrupted upon reaching a desired negative pressure in the motor vehicle brake booster system. Pump according to claim 11 or 12, characterized in that an oil supply for the pump ( 1 ) and that the oil supply is interrupted when the drive ( 11 ) of the rotor ( 7 ) is also interrupted. Pump according to one of the preceding claims, characterized in that the switching device ( 41 ) a valve unit ( 63 ), in particular a 4/2-way valve ( 65 ), for controlling the pressure chamber and the oil supply of the pump ( 1 ) comprising the pressure chamber or the oil supply with an oil supply pump ( 21 ), while the oil supply or the pressure chamber depressurises, preferably with a tank of the oil supply pump ( 21 ), connected is.