WO2000031419A1

WO2000031419A1 - Vacuum pump

Info

Publication number: WO2000031419A1
Application number: PCT/EP1999/008774
Authority: WO
Inventors: Dieter Otto
Original assignee: Luk Automobiltechnik Gmbh & Co. Kg
Priority date: 1998-11-24
Filing date: 1999-11-15
Publication date: 2000-06-02
Also published as: DE19982492D2

Abstract

The invention relates to a vacuum pump for supplying negative pressure to a consumer. Said vacuum pump has a housing and a pump insert which is arranged in said housing and which is driven by means of a drive device. The invention is characterised in that the pump insert can be coupled to and uncoupled from the drive device (20) by means of a controllable coupling device (43), in that the coupling device (43) can be controlled with the negative pressure from the consumer, and in that a valve device (58) is provided between the consumer and the coupling device (43). Said valve device opens a medium connection between the consumer and the coupling device (43) at a first negative pressure value in the consumer and interrupts this medium connection at a second negative pressure value, the first negative pressure value being lower than the second negative pressure value.

Description

Vacuum pump

description

The invention relates to a vacuum pump for supplying vacuum to a consumer, which has a housing and a pump insert which is arranged in the housing and which can be driven by a drive device.

Vacuum pumps of the type mentioned here are known. They are used in particular to supply a brake booster of a motor vehicle with negative pressure. The vacuum pump evacuates the brake booster, so that a negative pressure of, for example, up to -0.95 bar is present in the brake booster. The known pumps are firmly coupled to the drive device, which is formed in particular by a shaft of the drive machine of the motor vehicle that can be driven in rotation. Thus, the vacuum pump is also driven when the maximum achievable vacuum in the brake booster is reached and no braking power is required. This can occur, for example, when driving on the freeway. The known pumps therefore wear out unnecessarily. In addition, the permanent drive of the known vacuum pump constantly requires drive power, so that the fuel consumption of the engine of the motor vehicle is increased. It is therefore an object of the invention to provide a vacuum pump of the type mentioned at the outset which does not have these disadvantages.

The object is achieved with a vacuum pump which has the features of claim 1. This vacuum pump is used to supply a consumer with negative pressure. It has a housing and a pump insert which is arranged in the housing. The pump insert can be driven by a drive device. According to the invention, it is provided that the pump insert can be coupled and uncoupled to the drive device with a controllable coupling device. According to the invention it is further provided that the clutch device can be controlled with the negative pressure from the consumer, and that a valve device is provided between the consumer and the clutch device, which opens a medium connection between the consumer and the clutch device at a first negative pressure value present in the consumer and at a second negative pressure value the medium connection is interrupted, the first vacuum value being absolutely smaller than the second vacuum value. This means, starting from an ambient air pressure that is set as the reference variable to zero, the first vacuum value is, for example, approximately -0.5 and the second vacuum value is approximately -0.95 bar.

With the controllable coupling device according to the invention, a mechanically operating coupling and decoupling device for the vacuum pump is created that meets high safety requirements and that the vacuum pump can only be operated with the drive Direction connects when a vacuum has to be reduced again in the consumer system, for example for a brake booster of a motor vehicle. A mechanically driven vacuum pump is therefore provided, the drive of which can be interrupted, ie the pump can be switched off. For this purpose, the pump insert of the vacuum pump is connected to the drive device when the first negative pressure value, ie the minimum negative pressure (-0.5 bar), is reached, so that a higher negative pressure is built up in the consumer. When the higher second vacuum value (-0.95 bar), which corresponds to the maximum vacuum in the consumer, is reached, the pump insert is uncoupled from the drive device, that is, the vacuum pump is switched off. The vacuum pump according to the invention therefore only works when a vacuum in the consumer drops below the minimum vacuum value or reaches it. As a result, the pump is generally in operation for a shorter period of time so that its service life is increased. In addition, the energy consumption of the drive device is reduced, whereby fuel can be saved.

One embodiment is characterized in that the clutch device can be controlled via a piston guided in a cylinder, one piston surface of which can be acted upon by an ambient pressure, for example the ambient air pressure, and the other piston surface can be acted upon by the vacuum from the consumer. The valve device is therefore between the piston and the consumer. Instead of the piston, a membrane or a bellows can also be provided, in which the otherwise common sealing between the piston and cylinder walls is not required. This means that there is no friction when using a membrane or bellows.

A preferred embodiment is characterized in that the coupling device has a drive element, an output element and a spring element, the spring element keeping the input and output element coupled until the second vacuum value (-0.95 bar) is reached in the consumer, and that when Reaching the second vacuum value of the pistons separates the exhaust and drive element from each other. The clutch device is thus actuated purely mechanically via the piston, so that high safety requirements are met, as a result of which the vacuum pump according to the invention is particularly suitable for supplying the vacuum to the brake booster of a motor vehicle. When using a bellows, preferably made of metal, for controlling the coupling device, the spring element can also be dispensed with.

Furthermore, an embodiment is preferred in which the drive element is formed by a drive disk which is connected to the drive device in a rotationally fixed but axially displaceable manner, and in which the output element is implemented as an output disk which is connected in a rotationally fixed manner to a drive transmission element of the pump insert is. An easy-to-implement disc clutch is therefore provided, which is also inexpensive Stig is manufacturable and still has a high level of functional reliability.

An embodiment is particularly preferred which is characterized in that the spring element is a plate spring. The plate spring acts on the output element so that it rests on the drive element, which enables torque transmission from the drive side to the output side. Alternatively, the spring element can also be formed by one or more spring tongues which, starting from the drive transmission element of the pump insert, extend radially and are preferably arranged in a star shape, so that a uniform force can be applied to the output device.

An embodiment of the plate spring is particularly preferred, which is characterized in that it has an opening in the middle and is connected in a rotationally fixed manner to the drive transmission element of the pump insert. In the coupled position, the plate spring rotates with the output element, so that no wear can occur between the output element and the spring.

According to a development of the invention it is provided that the drive transmission element of the pump insert is designed as a shaft which is rotatably mounted in the housing. Thus, the plate spring having the central opening can be attached to the shaft in a particularly simple manner and connected to it in a rotationally fixed manner. In a preferred embodiment it is provided that the spring element, that is to say in particular the plate spring, is axially displaceable on the shaft. The plate spring can thus be displaced on the shaft in such a way that contact forces of different magnitudes can be applied to the output element. The coupling device according to the invention can thus be easily closed and opened.

A particularly preferred embodiment is characterized in that the spring element is supported with one side on the output element and with its other side on a clutch housing receiving the coupling device.

According to a further exemplary embodiment, it is provided that the output-side support and the housing-side support of the spring element are at a radial distance from one another. If a plate spring is used as a spring element, the area surrounding the opening, i.e. the support on the output side, and the radially outer area of the plate spring, i.e. the support on the clutch housing side, can be spaced apart from one another so that high spring forces can be applied.

An embodiment is particularly preferred in which the piston acts on the side of the spring element on which it is supported on the clutch housing. The support on the clutch housing side of the spring element thus forms a swivel or wi- derlager, wherein when the piston acts on the spring element, it is moved around the abutment, preferably pivoted.

According to a development of the invention, it is provided that the piston acts on a region of the spring element which, as seen from the support on the clutch housing side, lies radially on the inside. A rocker is thus formed with the spring element, which is pivoted about the housing-side support. Since the radially outer region of the spring element acts on the output element, a large leverage effect is also achieved, since — as mentioned above — the piston acts on a region of the spring element that lies radially on the inside. The vacuum can therefore be used for control in a particularly simple manner, since the long lever arm reinforces the effect of the vacuum.

In a preferred embodiment it is provided that the distance between the output-side support and the housing-side support is less than the distance between the housing-side support and the area of the spring element on which the piston acts. In other words, the housing-side support of the spring element is attached in such a way that lever arms are formed on the spring element, the radially inner lever arm being longer than the radially outer lever arm of the spring element. Thus, the lever arm between the housing-side support and the area of the spring element on which the piston acts is made longer than the lever arm between the clutch housing-side support and the output-side support. tongue of the spring element. This increases the force transmitted from the piston to the spring element.

In an exemplary embodiment, it is provided that the piston is designed as an annular piston, through whose passage opening the drive transmission element of the pump insert passes.

According to a development of the invention, it is provided that the ring piston has an axial extension which surrounds the through opening of the ring piston at least in regions. A particularly simple guidance of the annular piston is thus provided, which therefore does not tilt on its guide surface.

According to a development of the invention, it is provided that the axial extension acts on the spring element. The axial extension thus acts on the radially inner region of the spring element.

A preferred embodiment is characterized in that a rotary decoupling device is provided between the axial extension and the spring element. Thus, no wear occurs between the spring element and the annular piston or the axial extension, so that the controllable coupling device according to the invention is characterized by a long service life.

The drive device of the vacuum pump is preferably formed by the drive machine of a motor vehicle, with a shaft of the drive machine which can be driven in rotation with the drive element of the Coupling device is rotatably connected. The drive machine is preferably the internal combustion engine of a motor vehicle, the crankshaft and / or camshaft of which is connected to the drive element of the clutch device in a rotationally fixed manner.

The shaft which can be driven in rotation is preferably implemented as a hollow shaft through which an oil flow can be introduced into the clutch housing. The clutch can thus be cooled, the engine lubricating oil in particular being able to be introduced into the clutch housing.

An exemplary embodiment is particularly preferred in which the coupling device is a friction clutch, that is to say the drive element and the driven element do not form a positive connection, but rather a frictional engagement in the coupling position. Alternatively, it can be provided that the coupling device has a positive coupling. For this purpose, a dog clutch or a toothed clutch can be provided. The form-fitting coupling preferably has a synchronization which, for example, comprises synchronizing rings which are in particular conical and enable the input and output elements to be engaged. The conicity of the synchronizer rings increases the force of the vacuum-actuated piston sufficiently so that no additional levers have to be provided. Thus, even in the case of a positive coupling, the vacuum present in the consumer can be used to control the coupling in a particularly simple manner. According to a development of the invention it is provided that the drive transmission element of the pump insert is designed as a hollow drive shaft, the first end, on which the output element of the coupling device is provided, is arranged opposite the end of the rotationally drivable shaft of the drive machine, that the hollow drive shaft of the pump insert has a radially aligned Has channel that opens on the outer surface of the hollow drive shaft in the clutch housing on the side of the driven element facing away from the drive element, and that the other end of the hollow drive shaft opens into the pump insert. According to this embodiment, during operation of the vacuum pump, that is to say with the clutch device closed, oil is introduced into the hollow drive shaft of the drive machine into the hollow drive shaft of the vacuum pump, so that the vacuum pump is supplied with oil for lubrication, sealing of the gaps and for cooling. When the clutch device is open, ie when the vacuum pump is not working, oil is still conveyed through the hollow shaft of the drive machine into the hollow drive shaft of the vacuum pump, but according to the invention this oil can flow off into the clutch housing via the radially oriented channel in the hollow drive shaft.

A particularly preferred embodiment is characterized in that the valve device has a control piston movably guided in a valve bore, one control surface of which is subjected to the vacuum from the consumer and on the other control piston surface a two discontinuously switchable switching positions having spring device acts. This means that both switch positions are suddenly taken up, so that there is no smooth transition between the two switch positions. A step function is thus provided, that is to say a spring device which snaps into the other switching position. In particular, it is provided that in the first switching position of the spring device the control piston opens the medium connection and interrupts the medium connection in the second switching position, the first switching position being assigned the first vacuum value and the second switching position the second vacuum value. The opening and closing of the coupling device can therefore be realized in a particularly simple manner, wherein only mechanical components that meet high safety requirements are used.

In a preferred embodiment it is provided that the control piston of the valve device can be displaced against the force of a spring which acts on the one control surface of the control piston.

According to a particularly preferred embodiment, it is provided that the spring device, which snaps from one to the other switching position, has a preferred switching position, into which it snaps back in the unloaded state. The spring device is thus monostable. It can therefore be designed such that it is moved from its preferred switching position into the other switching position by the application of force or pressure, but this force or pressure is no longer present, the spring device automatically snaps back into its preferred switching position and remains there. It can optionally be provided that the preferred switching position is the first or second switching position of the spring device.

Another embodiment is characterized in that the valve device has an electromagnetically actuated control piston which is movably guided in a valve bore, the electromagnetic actuation of the control piston taking place as a function of the vacuum in the consumer, and in that the control piston is controlled in a first switching position in such a way that he opens the medium connection and interrupts the medium connection in a second switching position, the first switching position being assigned the first negative pressure value and the second switching position the second negative pressure value. The electromagnetic control of the control piston can be easily implemented, a sensor being provided to determine the negative pressure values in the consumer, which sensor is sensitive to pressure. When the first vacuum value is reached, the control piston is actuated and moved such that it opens the medium connection, so that the clutch can be closed. When the second pressure value is reached, the medium connection is interrupted again, so that the clutch is opened, whereby the vacuum pump is deactivated. The electromagnetic control of the control piston is preferably carried out in such a way that both switching positions can be adopted suddenly, that is to say without a substantial delay. According to a development of the invention, it is provided that the control piston in the second switching position releases a connection between the piston surface of the piston which can be subjected to negative pressure and the ambient air. One side of the piston can thus be exposed to the ambient air. In a preferred embodiment, the side of the cylinder space that is assigned to the other piston surface has a connection to the ambient air. When the second switching position is reached, the ambient air pressure is thus provided on both piston surfaces of the piston, so that the piston has no effect on the clutch device. Thus, the coupling device is held in frictional engagement via the spring element and a torque is transmitted.

Another embodiment is characterized in that the valve device has a movable control element in a valve bore, which opens the medium connection between the consumer and the coupling device in the first switching position and interrupts the medium connection in the second switching position, the first switching position being the first vacuum value and the second vacuum position is assigned to the second switching position. Such a valve device is characterized by a particularly simple construction.

According to a development of the invention, it is provided that the control element can be displaced against the force of a spring. In a particularly preferred embodiment, it is provided that the spring device having two discontinuously switchable switching positions acts on the control element, the first switching position being assigned to the first and the second switching position of the spring device to the second negative pressure value. Alternatively, it can be provided that the control element can be actuated electromagnetically, the electromagnetic actuation taking place as a function of the vacuum in the consumer. The control element is thus brought into the first and second switching positions with the electromagnetic actuation, so that the medium connection can be opened and closed.

In a particularly preferred embodiment, it is provided that the control element is implemented as a control ball which rests on a valve seat in one of the switching positions. With the control ball according to the invention, the valve device seals particularly well, so that there is no leakage.

Further refinements result from the subclaims.

The invention is explained in more detail below on the basis of exemplary embodiments with reference to the drawing. Show it:

FIG. 1 shows a vacuum pump with a first exemplary embodiment of a coupling device, FIG. 2 shows a vacuum pump with a second exemplary embodiment of a coupling device,

FIG. 3 shows a vacuum pump with a third exemplary embodiment of a coupling device,

Figures a first embodiment of a valve 4A and 4B valve device in different

Switch positions for controlling a

Coupling device,

Figures a second embodiment of a 5A and 5B valve device in different switching positions, and

Figures a third embodiment of a 6A and 6B valve device.

In Figure 1, a vacuum pump 1 is shown, which supplies a consumer, not shown here, with negative pressure via a supply connection 2. The vacuum pump 1 has a pump housing 3, in which a pump insert (not shown) is arranged. The pump insert preferably has a lifting ring in which a rotor receiving one or more radially movable vanes is inserted, that is to say a vane pump is implemented.

The pump housing 3 has a connection plate 4 with which the pump 1 can be attached to a motor housing of a drive machine. Preferably, the protrudes to the left of the end plate shown part of the pump 1 into the engine.

The pump housing 3 has an inner flange 5 which extends radially from a side plate 6. The pump insert is to the right of the side plate 6. The flange 5 is penetrated by a drive transmission element 7, which is designed as a shaft, in particular as a hollow drive shaft 8. The drive transmission element 7 or the hollow drive shaft 8 is provided for driving the pump insert, in particular — insofar as the pump insert is designed as a vane pump — connected to the rotor of the vane pump or forms part of the rotor. The hollow drive shaft 8 is rotatably mounted in the pump housing 3.

Radially on the outside of the side plate 6, an axial extension 9 is provided, which is circumferential, so that this axial extension 9, the circumferential flange 5 and the side plate 6 form a cylinder 10 'or annular space 10 which is closed by a cover 11. In the annular space 10, a piston 12 'is provided, which is designed as an annular piston 12. The annular piston 12 has a through opening 13 which surrounds the flange 5. In the area of the opening 13, the ring piston has an axial extension 14 which is slidably mounted on the flange 5, so that the ring piston 12 is axially movable. The flange 5 is preferably designed such that the annular piston 12 is connected to the housing 3 in a rotationally fixed manner. The radial piston 12 has a seal 15 lying radially on the outside, so that the piston divides two cylinder spaces 16 and 17 from each other airtight. An ambient pressure can be applied to the cylinder space 17 via a bore 18 ′, the ambient pressure being the ambient air pressure or a pressure present in the drive machine. The cylinder chamber 16 forms a negative pressure chamber 18 in which the negative pressure present in the consumer, which is generated with the vacuum pump 1, can be present. This means that the vacuum chamber 18 or the cylinder chamber 16 can be acted upon by the vacuum from the consumer via a valve device described below via a medium connection, not shown here.

The cover 11, which closes the annular space 10, is designed as a ring, with its passage opening being assigned a seal 19 which rests on the axial extension 14 of the annular piston 12. The vacuum chamber 18 or cylinder chamber 16 is therefore sealed airtight to the outside.

The vacuum pump 1 is driven by a drive device 20, of which only one drive shaft 21 is shown. This drive shaft is designed as a hollow shaft 22, which is formed in particular by a rotationally driven shaft of the drive machine. For example, the drive shaft 21 can be the crankshaft or camshaft of a drive machine, which is implemented in particular as an internal combustion engine of a motor vehicle. On a step 23 of the hollow shaft 22, a drive element 24 is non-rotatably but axially displaceable. The hub of the Drive elements 24 and the step 23 of the hollow shaft 22 have a toothing 25. The drive element 24 is designed as a drive disk 26. The drive disk 26 preferably has axially acting friction surfaces 27 and 28 on both sides, which can thus be realized as annular disks.

On a ring 29, which is rotatably and axially displaceably mounted on the drive transmission element 7, a clutch housing 30 is attached in a rotationally fixed manner, which is formed by an annular cover 31 and a pot-shaped part 32. The ring cover

31 is rotatably connected to the ring 29 at its through opening. Starting from the ring cover 31, the part 32 initially extends axially in the direction of the drive device 20, in order then to merge into a radial region 33. The part faces on the side facing the drive element 24

32 has a friction surface 34, which can interact with the friction surface 27 of the drive disk 26.

The hollow drive shaft 8 forming the drive transmission element 7 is stepped in the region of its end 35, which lies within the clutch housing 30. An output element 37 is arranged in a rotationally fixed manner on the step 36 located within the clutch housing 30. The output element 37 is designed as an output disk 38, which is arranged with its hub on the step 36 of the drive cavity 8. The driven pulley 38 has cams 39 on which a spring element 40 acts. Starting from the hollow drive shaft 8, the spring element 40 extends radially outwards and is preferably realized as a plate spring 41 which has a through opening 42 in the center, so that it can be connected to the ring 29 in a rotationally fixed manner. The drive element 24, the driven element 37 and the spring element 40 thus form a coupling device 43.

On its inside, the ring cover 31 has support elements 44 which act on the spring element 40. The spring element 40 or the plate spring 41 is thus clamped between the cam 39 lying radially on the outside on the driven disk 38, the support element 44 and the ring 29, as a result of which the spring element 40 or the plate spring 41 is pretensioned. As a result, the driven pulley 38, which is axially displaceable on the step 36, is acted upon by a spring force, so that the clutch device 43 is closed, ie a torque can be transmitted from the drive device 20 to the drive transmission element 7. The vacuum pump 1 is therefore coupled to the drive device 20.

In order to open the clutch device 43, the vacuum chamber 18 is subjected to a vacuum, as a result of which the annular piston 12 is pushed to the left by the ambient pressure present in the cylinder chamber 17. As a result, the axial extension 14 acts on a rotary decoupling device 45 which is arranged between the axial extension 14 and the ring 29 in such a way that no torque transmission takes place between the ring 29 and the annular piston 12. The rotary decoupling device 45 can be designed as a slide bearing or as an axial roller bearing. be formed and is axially displaceable on the flange 5. The movement of the ring piston 12 to the left forces the ring 29 to the left via the rotary decoupling device 45, as a result of which a force acting to the left is applied to the spring element 40 in the area of the passage opening 42. As a result, the spring element 40 deforms in such a way or is pivoted about the supporting elements 44 in such a way that the radially outer region of the spring element 40 moves to the right, that is to say a pressure relief on the cam 39 is created, as a result of which the coupling device 43 is opened. In order to amplify the force exerted by the annular piston 12 on the spring element 40, it is provided that the support elements 44 lie at a radial distance from the ring 29, and that lever arms A and B are formed on the spring element 40, the radially outer lever arm A being shorter as the lever arm B is formed. The length of the lever arm A of the spring element 40 is formed by the distance that the support elements 44 have from the cams 39. The length of the lever arm B is thus formed by the distance between the support elements 44 and the ring 29, on the step of which the spring element 40 rests. The spring element 40 can thus rock on the support elements 44, an amplification of the force applied by the annular piston 12 being amplified by the different lengths of the lever arms A and B.

If the vacuum in the vacuum chamber 18 drops to a certain value or if the vacuum chamber 18 is also subjected to the ambient pressure, the annular piston 12 moves to the right again. whereby the spring element 40 acts again on the cam 39, so that the clutch device 43 is closed again and a torque transmission takes place from the drive device 20 to the drive transmission element 7, whereby the vacuum pump 1 is in turn driven.

The hollow shaft 22 of the drive device 20 has a throttle 46 or diaphragm, so that a limited oil flow can flow through the hollow shaft 22. The oil flow enters the drive hollow shaft 8 when the clutch is closed and thus reaches the pump insert of the vacuum pump 1 via the channel 47 of the drive hollow shaft 8. The vacuum pump can have a metering device (not shown here) which only allows a certain amount of oil to flow to the pump insert. In addition, the metering device allows an oil supply to the vacuum pump 1 only during its operation.

When the clutch device 43 is open, there is a small distance between the drive disk 26 and the driven disk 38, so that the oil flowing into the hollow drive shaft 8 can flow into the clutch housing 30 via a radial channel 48 and can pass between the drive disk 26 and the driven disk 38 then flow out of the clutch housing 30 in the area of part 32 in the direction of arrow 49. Thus, the oil flowing in through the hollow shaft 22, which is preferably the engine oil of the drive machine, is used to supply the vacuum pump 1 when the coupling device 43 is closed and for cooling purposes when the coupling device 43 is open and lubrication of the friction surfaces 27, 28 and 34 are used, the driven disk 38 also having a friction surface 50 lying radially on the outside, which is then also cooled by the oil.

Of course, it is also possible not to supply the clutch device 43 with the oil flow, that is to say to provide a dry clutch. Instead of the frictional clutch device 43 described here, a positive clutch can also be used. In particular, a claw coupling or a coupling having a toothing can be used for the positive coupling. These form-fitting couplings preferably have synchronizer rings which enable the input and output device to be engaged. The synchronizer rings, not shown here, are preferably conical, so that the force of the vacuum-actuated annular piston 12 is amplified sufficiently so that no levers are required.

The friction surfaces 27, 28, 34 and 50 are preferably designed as friction linings. Alternatively, however, it can also be provided that the drive disk 26 consists of plastic and the driven disk 38 and the part 32 consist of a steel or aluminum. Of course, it is also possible that the driven pulley 38 and the part 32 are made of plastic and the drive pulley 26 is made of steel or aluminum. Of course, it is also possible to manufacture the drive pulley 26, the driven pulley 38 and the part 32 from plastic. For the latter two ages native friction linings on the friction surfaces 27, 28, 34 and 50 can be dispensed with.

As an alternative to the rotationally fixed connection between the clutch housing 30 and the ring 29 described in connection with FIG. 1, the clutch housing 30 can also be mounted directly on the driven disk 38, so that the ring 29 can be dispensed with.

On the side of the driven disk 38 facing the plate spring 41, tongues 51 are attached or formed in one piece with the driven disk 38. When the clutch device 43 is opened, they move the driven disk 38 to the right, since the plate spring 41 or the spring element 40 engages behind the tongues 51. With the tongues 51, the play of the clutch device 43 is set and thus prevents a torque (slip torque) being transmitted when the plate spring 41 is under force due to friction when the clutch is not sufficiently open.

FIG. 2 shows a second exemplary embodiment of a coupling device 43 which interacts with the vacuum pump 1. Parts that are the same as in FIG. 1 are provided with the same reference numerals, so that they will not be described again. The annular space 10 is open, that is, the cover 11 is not provided. The ambient pressure acts on the left side of the ring piston 12. The vacuum present in the consumer acts in the vacuum chamber 18 on the right side of the ring piston 12. The flange 5 has a seal 52, which bears against the axial extension 14 of the annular piston 12, so that the vacuum chamber 18 is sealed airtight to the outside. A radial extension 53 adjoins the axial extension 14 of the annular piston 12, which extends radially inward as viewed from the extension 14. The radial extension 53 interacts with the ring 29 and engages behind this ring 29 in a form-fitting manner. On the ring 29, the spring element 40 or the plate spring 41 is also fixed in a rotationally fixed manner in the region of its passage opening 42. The inside diameter in the area of the extension 53 is somewhat larger than the outside diameter of the ring 29. Between the end of the extension 53 and the stepped ring 29, the plate spring is virtually clamped. The extension 53 can not slip over the ring 23. The axial movement of the ring piston 12 is thus transmitted to the ring 29, that is to say the ring 29 is carried along by the ring piston 12. The plate spring 41 is supported on the clutch housing 30. The clutch housing 30 is not closed here, so the ring cover 31 is not provided.

With pre-tension, the plate spring 41 presses on the output disk 38 via the cams 39, so that the clutch device 43 is closed, that is to say there is a torque transmission from the drive device 20 to the pump insert.

If the vacuum in the vacuum chamber 18 is large enough, the annular piston 12 moves to the right. To do this, he must use the force of the plate spring 41 overcome. Since the ring 29 is non-rotatably connected to the plate spring and is mounted on the drive hollow shaft 8, an axial movement of the ring 29 is possible. The contact surface 54 between the ring 29 and the annular piston 12 forms an axial slide bearing. A roller bearing can of course also be provided. This plain bearing or roller bearing is necessary when the ring 29 rotates at the pump speed, but the annular piston 12 is non-rotatably connected to the pump housing 1, for example via the flange 5.

FIG. 3 shows a third exemplary embodiment of a coupling device 43 which can connect the pump insert of the vacuum pump 1 to the drive device 20. The same parts as in Figures 1 and 2 are provided with the same reference numerals, so that reference is made to their description.

The annular piston 12 is acted upon by compression springs 55 which urge the annular piston 12 to the left. The annular piston acts directly on the plate spring 41, which extends from the radially outer region of the annular piston 12 to the radially inner clutch housing 30. The plate spring 41 is thus supported on the clutch housing 30, on the cover 11 closing the annular space 10 and on the annular piston 12. The annular space 18 is subjected to the vacuum from the consumer via an inlet 56. As a result, the annular piston 12 moves to the right, whereby the plate spring 41 is relieved. As a result, the cup-shaped coupling housing 30 can itself move to the left. As a result, the clutch housing 30 does not exert any force on the drive disk 26, so that no force is transmitted to the driven disk 38. The clutch housing is rotationally decoupled from the drive disk 26 via a rotary decoupling device 100, which can be designed as a disk. The clutch housing 30 is arranged in a rotationally fixed manner. On the other hand, if the negative pressure drops, the annular piston 12 moves to the left, as a result of which the plate spring 41 is pivoted about its cover-side support point 57, as a result of which a force is transmitted to the clutch housing 30, which engages behind the plate spring. As a result, the clutch housing 30 and the drive disk 26 on the hollow shaft 22 are moved to the right, so that a frictional connection with the driven disk 38 is provided. The pump insert of the vacuum pump 1 can thus be driven.

The exemplary embodiment according to FIG. 3 is characterized in that the outer diameter of the clutch housing 30 can be made smaller than the outer diameter of the clutch housing 30 according to FIGS. 1 and 2. This facilitates the connection or coupling of the vacuum pump 1 to a motor housing, since there is less sealing surface. In particular, it is provided that the vacuum pump 1 is connected to an engine housing of a drive machine on an axial extension 58 on the cover 11.

Instead of the annular piston 12 described in Figures 1 to 3 can be used to control the clutch device 43 a membrane, not shown here, or a bellows, not shown here, are used. As a result, the seals on the annular piston 12 can be dispensed with. Thus, when using a diaphragm or a bellows, no friction occurs, as occurs between the annular piston 12 and the cylinder wall. When a preferably metallic bellows is used, it can also act as a spring and thus provide the contact pressure that the spring element 40 applies. When using a bellows, the spring element 40 can thus be dispensed with.

A valve device 58 is shown in different switching positions in FIGS. 4A and 4B. With the valve device 58, a medium connection between the consumer and the vacuum space 18 of the annular space 10 is opened and interrupted. For this purpose, the valve device has a control piston 60 movably guided in a valve bore 59. The control piston 60 has a double stage 60 ′ approximately in the middle, so that there is an area 61 with a diameter that is smaller than that of the other areas of the control piston 60.

A control piston surface 62 of the control piston 60 lying on the left in FIGS. 4A and 4B is acted upon by a spring 63, which is supported at one end on the bottom of the valve bore 59. The other end of the spring 63 lies against the control piston surface 62. The control piston surface 62 is also acted upon by the negative pressure from the consumer, which is connected to the supply channel 64 of the valve device 58. The supply channel 64 divides into two subchannels 66 and 67 in the valve body 65, the subchannel 66 opening out into the valve bore 59 behind the control piston surface 62. The path of the control piston 60 is limited by a spring device 68, which can be designed as a leaf spring. The spring device 68 is inserted into a groove 69, which can be designed as an annular groove. The groove 69 is made in the valve bore 59. The length of the untensioned spring leaf of the spring device 68 is greater than the diameter of the valve bore. The spring device 68 acts on the other control piston surface 70 of the control piston 60. Due to the special design of the spring device 68, the latter can assume two switching positions, the transition between the two switching positions taking place discontinuously, that is to say in an abrupt manner. In the switching position shown in Figure 4A, the control piston is shifted to the right, so that a line 71, which leads from the valve bore 59 to the vacuum chamber 18 of the annular space 10, is in medium connection with a line 72, the line 72 terminating freely in the room, for example , so that the ambient pressure can be introduced into the vacuum chamber 18. The switching position of the control piston 60 shown in FIG. 4A causes the clutch device 43 to be closed, since only the spring element 40 acts on the clutch device 43, since the annular piston 12 is acted upon on both sides by ambient pressure and therefore does not move. The negative pressure in the consumer is between the first and second negative pressure value, but it is greater than -0.5 bar. The vacuum pump 1 must therefore the consumer, not shown here do not supply with a higher vacuum. The spring device 68 is in its second switching position.

If the vacuum present in the consumer drops below a minimum vacuum (-0.95 bar), this vacuum acts on the control piston surface 62 via the supply line 64 and the sub-channel 66, so that the control piston 60 is moved into its first switching position according to FIG. 4B . In order to be able to reach the switching position shown in FIG. 4B, the suppressor must be such that the spring device 68 snaps from the switching position shown in FIG. 4A in FIG. 4B. This moves the control piston 60 and provides a medium connection between the supply line 64 and the line 71, which is connected to the vacuum chamber 18. The control piston 60 closes the line 72 so that the ambient pressure cannot get into the line 71. In the switching position of the control piston 60 shown in FIG. 4B, the vacuum chamber 18 is thus acted upon by the vacuum present in the consumer, so that the clutch device 43 is opened when the vacuum reaches the second vacuum value, which can be, for example, -0.95 bar. If the negative pressure present in the consumer drops back to the first negative pressure value, that is to say the negative pressure behind control surface 62 becomes lower again (approximately -0.5 bar), spring device 68 snaps back into the second switching position shown in FIG. 4A, again causing the Ambient pressure is passed into the vacuum chamber 18 so that the clutch device device is closed again, so that the vacuum pump can generate a larger vacuum in the consumer again. The coupling device therefore remains closed until the negative pressure value in the consumer again corresponds to the second negative pressure value (-0.95 bar).

The spring device 68 preferably has a preferred switching position, into which it snaps in the unloaded state and which it then also maintains if the unloaded state is present or the vacuum from the consumer does not rise above a switching value. The spring device 68 thus has a stable switching position.

FIGS. 5A and 5B show a second exemplary embodiment of a valve device 58. The valve device 58 has a valve bore 59 in which a control element 73 is movably arranged. The valve bore 59 is closed with a plug 74 which has a through opening 75. The control element 73, which is preferably designed as a control ball 76, can move between the plug 74 and the bottom 59 ′ of the valve bore 59. The line 64, which leads to the consumer, opens into the floor 59 '. In FIG. 5A, the control element 73 lies sealingly on a valve seat 77 which surrounds the mouth of the through opening 75.

The control element 73 is acted upon by a compression spring 63, so that it is pushed onto the valve seat 77. In the shown in Figure 5A Switching position is the supply line 64 connected to the consumer with the line 71 in medium connection, which leads to the vacuum chamber 18. The medium connection between the consumer and the vacuum chamber 18 is thus opened. 5A shows the second switching position of the valve device 58, which is assigned to the second vacuum value in the consumer. The clutch device is open and the ambient pressure in line 72 is separated from the annular piston 12.

FIG. 5B shows the first switching position of the valve device 58, which is assigned to the first vacuum value. The control element 73 is not seated on the valve seat 77, so that the negative pressure present in the consumer is not led to the negative pressure chamber 18 via the supply line 64 and the line 71. Rather, ambient pressure passes from line 72 via through bore 75 to line 71, so that the annular piston 12 is acted upon by the ambient pressure on both sides, as a result of which the clutch is closed and vacuum pump 1 operates. The control element 73 is shifted to the left against the force of the compression spring 63. In the exemplary embodiment according to FIGS. 5A and 5B, the control element 73 is actuated via an electromagnetic actuating device 78, the actuating device comprising a magnet 79 and an armature which is axially movable in the coil and from which an armature rod 80 extends. The armature rod 80 forms the actuating element for the control element 73. In FIG. 5B, the armature rod 80 has partially moved out of the coil and passes through the through opening 75 of the plug 74. The control element 73 is thus displaced to the left via the anchor rod 80 against the force of the spring 63.

The electromagnetic actuator 78 is controlled by an electronic control device

(not shown) controlled, which is assigned a sensor, not shown here. The sensor is, for example, a pressure sensor which is arranged in the consumer and determines the negative pressure present in the consumer. This negative pressure value is transmitted to the control device, which thus controls the electromagnetic actuating device 78 as a function of the negative pressure present in the consumer. If the vacuum present in the consumer is below the first vacuum value

(-0.5 bar), the actuating device 78 is actuated so that the control element 73 is lifted from the valve seat 77, whereby the medium connection between the supply line 64 and line 71 is closed. If the vacuum present in the consumer reaches the second vacuum value

(-0.95 bar), the actuating device 78 is controlled in such a way, for example switched off, that the control element 73 comes to rest on the valve seat 77, as shown in FIG. 5A. This opens the medium connection between the consumer and the pressure chamber 18, since the negative pressure present in the supply line 64 can be passed on to the line 71, which leads to the negative pressure chamber 18. FIGS. 6A and 6B show a third exemplary embodiment of a valve device 58, the same parts as in FIGS. 4 and 5 being provided with the same reference symbols. Therefore, only differences to the other valve devices 58 will be discussed in the following.

Instead of the electromagnetic actuating device 78 shown in FIGS. 5A and 5B, a mechanical control is provided which has the spring device 68. The spring device 68, which can assume the two switching positions, acts on an actuation extension 81, which can be attached to the control element 73 or to the spring device 68.

In the exemplary embodiment according to FIGS. 6A and 6B, the spring device 68 is arranged in the region of the mouth of the valve bore 59 and held there at its ends, so that the effective region of the spring device 68 extends over the mouth of the valve bore 59. FIG. 6A shows the valve device 58 in the second switching position, in which the negative pressure applied by the supply line 64 is passed on from the consumer via the passage opening 75 to the line 71, which opens into the vacuum chamber 18. The control element 73 is lifted off the valve seat 77. The spring device 68 is shown in the second switching position, in which the negative pressure moves the spring device 68 into the valve bore 59. The supply line 64 opens between the plug 74 and the spring device 68 in the valve bore 59. The line 71 opens between the Plug 74 and the bottom of the valve bore 59. An ambient pressure is present on the outside 82 of the spring device 68. The outside 82 is therefore facing away from the valve bore 59.

6B shows the valve device 58 in the first switching position. The spring device 68 is in its first switching position, that is, the negative pressure is not sufficient to move the spring device 68 into the valve bore 59. As a result, the compression spring 63 can press the control element 73 onto the valve seat 77, since the actuation extension 81 is also displaced to the right as a result of the displacement of the spring device 68 to the right. The ambient pressure from line 72 thus passes via line 71 to the annular piston, which is thus subjected to ambient pressure on both sides. The coupling device is thus closed and the vacuum pump works.

With the coupling device or with the coupling device controlled according to the invention, it is therefore possible to switch the vacuum pump, which generates the vacuum required in the consumer, on and off as required. Since the vacuum pump does not have to be in constant operation, it can be switched off with the coupling device according to the invention if no higher vacuum has to be generated. Because the vacuum pump does not have to be driven permanently, drive energy can thus be saved. In particular in motor vehicles with internal combustion engines, the fuel consumption of the internal combustion engine can be lowered since the vacuum pump does not have to be driven at idle.

The patent claims submitted with the application are proposals for formulation without prejudice for the achievement of further patent protection. The applicant reserves the right to claim further features previously only disclosed in the description and / or in the drawings.

Back-references used in sub-claims indicate the further development of the subject matter of the main claim through the features of the respective sub-claim; they are not to be understood as a waiver of the achievement of independent, objective protection for the characteristics of the related subclaims. However, the subjects of these subclaims also form independent inventions which have a design which is independent of the subjects of the preceding subclaims.

The invention is also not limited to the exemplary embodiments shown in the description. Rather, numerous changes and modifications are possible within the scope of the invention, in particular such variants, elements and combinations and / or materials, for example by combining or modifying individual ones, in connection with those described in and in the general description and the embodiments and the claims the features or elements or method steps contained in the drawings are inventive and ned characteristics lead to a new object or to new process steps or process step sequences, also insofar as they relate to manufacturing, testing and working processes.

Claims

Expectations

1. Vacuum pump for supplying vacuum to a consumer, which has a housing and a pump insert which is arranged in the housing and which can be driven via a drive device, characterized in that the pump insert with a controllable coupling device (43) to the drive device (20) - And can be uncoupled that the coupling device (43) can be controlled with the negative pressure from the consumer, and that between the consumer and the coupling device (43) a valve device (58) is provided, which has a medium connection between a first vacuum value present in the consumer The consumer and the coupling device (43) open and interrupt the medium connection at a second negative pressure value, the first negative pressure value being less than the second negative pressure value.

2. Vacuum pump according to claim 1, characterized in that the coupling device (43) via a piston in a cylinder (10 ')

(12 ') can be controlled, one piston surface of which can be acted upon by an ambient pressure and the other piston surface of which the vacuum can be applied from the consumer.

3. Vacuum pump according to one of the preceding claims, characterized in that the coupling device (43) has a drive element (24), an output element (37) and a spring element (40), the spring element (40) until reaching the second Vacuum value in the consumer keeps the input and output element coupled, and that when the second vacuum value of the pistons (12 ') is reached, the output and drive element is separated.

4. Vacuum pump according to one of the preceding claims, characterized in that the drive element (24) is formed by a drive disc (26) which is connected to the drive device (20) in a rotationally fixed but axially displaceable manner, and in that the output element (37 ) is realized as an output disk (38), which is connected in a rotationally fixed manner to a drive transmission element (7) of the pump insert.

5. Vacuum pump according to one of the preceding claims, characterized in that the spring element is a plate spring (41).

6. Vacuum pump according to one of the preceding claims, characterized in that the spring element (40) is formed by a plurality of spring tongues preferably arranged in a star shape.

7. Vacuum pump according to one of the preceding claims, characterized in that the plate spring (41) has an opening (42) in the center and is rotatably connected to the drive transmission element (7).

8. Vacuum pump according to one of the preceding claims, characterized in that the drive transmission element (7) is designed as a shaft which is rotatably mounted in the housing (3).

9. Vacuum pump according to one of the preceding claims, characterized in that the spring element (40) is axially displaceable on the shaft.

10. Vacuum pump according to one of the preceding claims, characterized in that the spring element (40) is supported with its one side on the output element (24) and with its other side on a clutch housing (43) receiving the clutch housing (30).

11. Vacuum pump according to one of the preceding claims, characterized in that the output-side support and the housing-side support of the spring element (40) have a radial distance from one another.

12. Vacuum pump according to one of the preceding claims, characterized in that the piston (12 ') acts on the side on the spring element (40) on which it is supported on the clutch housing (30).

13. Vacuum pump according to one of the preceding claims, characterized in that the piston (12 ') on a region of the spring element (40) acts, which - seen from the housing-side support - is located radially on the inside.

14. Vacuum pump according to claim 11 to 13, characterized in that the distance between the output-side support and the housing-side support is less than the distance between the housing-side support and the area of the spring element

(40) on which the piston (12 ') acts.

15. Vacuum pump according to one of the preceding claims, characterized in that the piston (12 ') is designed as an annular piston (12) through whose through opening (13) the drive transmission element (7) passes.

16. Vacuum pump according to one of the preceding claims, characterized in that the annular piston (12) has an axial extension (14) which the

Through opening (13) surrounds at least in some areas.

17. Vacuum pump according to one of the preceding claims, characterized in that the axial extension (14) acts on the spring element (40).

18. Vacuum pump according to one of the preceding claims, characterized in that a rotary decoupling device (45) is provided between the axial extension (14) and the spring element (40).

19. Vacuum pump according to one of the preceding claims, characterized in that the drive device (20) is the prime mover Motor vehicle, a rotatably drivable shaft (21) of the drive machine being connected in a rotationally fixed manner to the drive element (24) of the coupling device (43).

20. Vacuum pump according to one of the preceding claims, characterized in that the drivable shaft (21) is realized as a hollow shaft (22) through which an oil flow can be introduced into the clutch housing (30).

21. Vacuum pump according to one of the preceding claims, characterized in that the coupling device (43) is a friction clutch.

22. Vacuum pump according to one of the preceding claims, characterized in that the drive transmission element (7) of the pump insert is designed as a hollow drive shaft (8), the first end (35) on which the output element (38) of the coupling device (43) is arranged is arranged at the end of the rotatably drivable shaft (21) opposite, this end of the rotatably drivable shaft (21) in the coupling housing (30), that the drive hollow shaft (8) of the pump insert has a radially oriented channel (48) which on the The outer surface of the hollow drive shaft (8) opens into the clutch housing (3) on the side of the driven element (24) facing away from the drive element (38), and that the other end of the hollow drive shaft (8) opens into the pump insert.

23. Vacuum pump, in particular according to one of the preceding claims, characterized in that the valve device (58) has a control piston (60) which is movably guided in a valve bore (59), one control piston surface (62) of which is subjected to the negative pressure of the consumer and on the other control piston surface (70) a spring device (68 which has two discontinuously switchable switching positions) ) acts, wherein in the first switching position of the spring device (68) the control piston (60) opens the medium connection and interrupts the medium connection in the second switching position, and wherein the first switching position is assigned the first vacuum value and the second switching position the second vacuum value.

24. Vacuum pump according to claim 23, characterized in that the control piston is displaceable against the force of a spring (63) which acts on the one control surface (62).

25. Vacuum pump according to claim 23, characterized in that the spring device (68) has a preferred switching position, into which it snaps back in the unloaded state.

26. Vacuum pump according to claim 23 or 25, characterized in that the first or second switching position is the preferred switching position.

27. Vacuum pump, in particular according to one of claims 1 to 22, characterized in that the valve device (58) has an electromagnetically actuated control piston (60) which is movably guided in a valve bore (59), the e- Electromagnetic actuation of the control piston takes place as a function of the vacuum in the consumer, and that the control piston (60) is controlled such that it opens the medium connection in a first switching position and interrupts the medium connection in its second switching position, the first switching position having the first vacuum value and the second switching position is assigned the second vacuum value.

28. Vacuum pump according to one of the preceding claims, characterized in that the control piston (60) in the second switching position releases a connection between the piston surface of the piston (12 ') which can be subjected to negative pressure and the ambient air.

29. Vacuum pump according to one of claims 1 to 22, characterized in that the valve device

(58) has a control element (73) which is movable in a valve bore (59) and which opens the medium connection between consumer and coupling device (43) in a first switching position and interrupts the medium connection in a second switching position, the first switching division having the first vacuum value and the second switching position is assigned the second vacuum value.

30. Vacuum pump according to claim 29, characterized in that the control element (73) can be displaced against the force of a spring (63).

31. Vacuum pump according to claim 29 or 30, characterized in that a spring device (68) having two discontinuously switchable switching positions acts on the control element (73), the first switching position being assigned to the first and the second switching position of the spring device (68) to the second negative pressure value is.

32. Vacuum pump according to one of claims 29 or 30, characterized in that the control element can be actuated electromagnetically, the electromagnetic actuation taking place as a function of the vacuum in the consumer.

33. Vacuum pump according to one of claims 29 to 32, characterized in that the control element (73) thus control ball (76) is realized, which rests in one of the switching positions on a valve seat (77).

34. Vacuum pump for supplying vacuum to a consumer, which has a housing and a pump insert which is arranged in the housing and which can be driven by a drive device, characterized by at least one inventive feature disclosed in the application documents.