WO2011116747A1

WO2011116747A1 - Hydraulic system

Info

Publication number: WO2011116747A1
Application number: PCT/DE2011/000274
Authority: WO
Inventors: Andreas GÖTZ
Original assignee: Schaeffler Technologies Gmbh & Co. Kg
Priority date: 2010-03-25
Filing date: 2011-03-16
Publication date: 2011-09-29
Also published as: DE102011014096A1; CN102812271B; DE112011101034A5; CN102812271A

Abstract

The invention relates to a hydraulic system for controlling a continuously variable, adjustable belt-driven conical pulley transmission, comprising two conical pulley pairs, around which a belt is looped and which each comprise two conical pulleys, of which one can be moved axially in relation to the pressure in an associated pressing chamber, and comprising a torque sensor, which comprises a torque sensor chamber, which is connected to a hydraulic energy source and to at least one of the pressing chambers, and a further torque sensor chamber, in order to provide an underdrive operating mode or an overdrive operating mode of the belt-driven conical pulley transmission. The invention is characterized in that the hydraulic system comprises at least three fixed orifices in order to provide at least one further operating mode of the belt-driven conical pulley transmission in addition to the underdrive operating mode or the overdrive operating mode.

Description

Hydrauliksvstem

The invention relates to a hydraulic system for driving a continuously variable conical-pulley belt, with two entwined by a belt wrap conical disk pairs, each comprising two conical disks, one of which is axially displaceable in response to the pressure in an associated pressure chamber, and with a torque sensor, the a torque sensing chamber connected to a source of hydraulic power and communicating with at least one of the apply chambers and including another torque sensing chamber for representing an underdrive operating stage or an overdrive operating stage of the belt pulley belt transmission.

From the German patent application DE 10 2008 059 807 A1 a generic hydraulic system with adjustable hydraulic resistances is known.

The object of the invention is to provide a hydraulic system according to the preamble of claim 1, which is simple in construction and inexpensive to produce.

The object is in a hydraulic system for controlling a continuously variable conical-pulley belt, with two looped by a belt wrapper pairs of conical disks, each comprising two conical disks, one of which is axially displaceable in response to the pressure in an associated pressure chamber, and with a torque sensor, a torque sensing chamber connected to a hydraulic power source communicating with at least one of the pressing chambers and comprising a further torque sensing chamber for representing an underdrive operating stage or an overdrive operating stage of the conical-pulley transmission, in which the hydraulic system is at least includes three fixed apertures to represent, in addition to the underdrive mode or the overdrive mode, at least one further stage of operation of the cone pulley belt transmission. The fixed panels are single panels whose hydraulic resistance is not adjustable. The different operating stages of the conical-pulley belt drive serve to provide different transmission ratios between an input shaft and an output shaft of the conical pulley belt transmission display. Torque sensors of conical pulley belt transmissions can be single-stage, two-stage or fully variable. In order to achieve an ideal contact between the conical disks and the belt, the torque sensor should react as continuously as possible. However, a fully variable torque sensor is very expensive to manufacture. The hydraulic system according to the invention combines the cost advantages of a two-stage torque sensor with the advantages of the steplessity of the variable torque sensor. The advantages of the hydraulic system according to the invention include the fact that only small changes compared to a two-stage torque sensor are required. According to an essential aspect of the invention, it is not the hydraulic resistances themselves that are varied, but the number of single diaphragms, preferably connected in parallel. With three fixed panels or single panels, up to five levels of operation can be realized. The single apertures provide the advantage that they are easy to control in terms of tolerance. The combination of open and closed diaphragms as well as suitable diaphragm diameters of the individual diaphragms or their exact axial position relative to the axially displaceable conical disc or spacer disc, the contact pressure or the associated law, which is also referred to as Anpressgesetz, in a simple manner very accurate and be reproducibly fine tuned.

A preferred embodiment of the hydraulic system is characterized in that the hydraulic system comprises four fixed orifices to represent, in addition to the underdrive operating stage or the overdrive operating stage, at least two further operating stages of the conical-pulley belt transmission. Of the four fixed apertures, two are preferably pairwise combined to represent different functions. A first diaphragm pair is preferably switchable or connected between the further torque sensor chamber and one of the contact pressure chambers. A second pair of diaphragms is preferably switchable between the further torque sensing chamber and a pressure relief space, such as a tank. The second diaphragm pair is thus connected to the output side of the hydraulic system. As a result, the apertures of the second aperture pair are also referred to as the aperture-side apertures.

A further preferred embodiment of the hydraulic system is characterized in that the hydraulic system comprises four fixed shutters to represent a total of five operating - stages of the conical-pulley belt transmission. This combination has proved to be particularly advantageous in the context of the present invention. A further preferred embodiment of the hydraulic system is characterized in that the fixed shutters are connected in parallel, arranged relatively close to each other and / or identical. The fixed orifices are preferably arranged and designed in the axial and / or radial direction in such a way that the exact same pressures act on all fixed orifices and the centrifugal forces cancel each other out. This provides the great advantage that the contact pressure is independent of the speed.

A further preferred embodiment of the hydraulic system is characterized in that the fixed orifices are arranged in an input shaft of the conical-pulley belt transmission and are switched on or off via the axial position of a displaceable on the input shaft guide disk of a first set of cone pulleys. The arrangement of the fixed aperture in the input shaft is space neutral and has been found in the context of the present invention for the desired function of the aperture as optimal.

A further preferred embodiment of the hydraulic system is characterized in that in a first operating state, a first and a second aperture closed and a third and a fourth aperture, at least partially, are open. The first operating state preferably corresponds to an underdrive operating state. The third and the fourth aperture are preferably fully opened in the first operating state.

Another preferred exemplary embodiment of the hydraulic system is characterized in that, in a second operating state, the second diaphragm is closed and the first, third and fourth diaphragm are at least partially opened. The first panel is preferably partially opened in the second operating state. The third and fourth aperture are preferably completely open in the second operating state. In the second operating state, a transmission ratio between 1 and 2 is set, preferably about 1.8.

Another preferred exemplary embodiment of the hydraulic system is characterized in that in a third operating state, the second and third shutters are closed and the first and fourth shutters are at least partially opened. The first and the fourth aperture are preferably fully open in the third operating state. In the third operating state, a transmission ratio of approximately 1, in particular exactly 1, is preferably set. A further preferred embodiment of the hydraulic system is characterized in that in a fourth operating state, the third diaphragm is closed and the first, second and fourth diaphragm, at least partially, are open. The first panel is preferably completely open in the fourth operating state. The second and fourth aperture are preferably partially open in the fourth operating state. In the fourth operating state, a transmission ratio is preferably set which is less than 1, in particular about 0.75.

Another preferred exemplary embodiment of the hydraulic system is characterized in that, in a fifth operating state, the first and second shutters are at least partially opened and the third and fourth shutters are closed. The first and second aperture are preferably fully open in the fifth operating state. In the fifth operating state, a transmission ratio of approximately 0.6 is preferably set.

If appropriate, the invention also relates to a method for operating a hydraulic system described above.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, various embodiments are described in detail.

FIGS. 1 to 5 each show a simplified representation of a conical-pulley belt drive in longitudinal section with a hydraulic system according to the invention in five different operating states.

In the figures 1 to 5 a conical-pulley belt transmission 1 in five different operating states simplified in half section is shown. By a symbol 2, the gear ratio in the respective operating state is indicated in the figures 1 to 5 at the top left in each case.

The symbol 2 greatly simplifies a conical-pulley belt drive with a first conical disk pair or conical disk set 3 and a second conical disk pair or conical disk set 4. An arrow 5 indicates that the first conical disk pair 3 is driven. The two conical disk pairs 3 and 4 are connected by Means 6, such as a chain, connected to each other to transmit a torque from the driven first conical disk pair 3 to the second conical disk pair 4.

The conical-pulley belt transmission 1 shown in FIGS. 1 to 5 comprises, like the conical-pulley belt transmission disclosed in the German patent application DE 10 2008 059 807 A1, an input shaft 10 which, preferably in one piece, is formed with a fixed pulley, not shown. A conical disk 12, which is also referred to as a travel plate or loose disk, is axially displaceable, but non-rotatably connected to the input shaft 10.

The conical disk 12 with the input shaft 10 belong to a first, driven conical disk set or cone pulley pair, which are connected by a belt 14, in particular a chain, with a second, not shown conical disk set. Due to the design of the two conical disk sets and the belt 14, the transmission ratio between the input shaft 10 and an output shaft associated with the second set of conical disks can be varied continuously.

On the back of the cone pulley 12, which is also referred to as a travel plate, is a

Torque sensor 15 indicated with a support ring 16 which, for example, by a press fit, is firmly connected to the input shaft 10. Between the support ring 16 and a sensor piston 20 rolling elements 18 are indicated, which are designed here as balls.

The sensor piston 20 is, as indicated by an axial toothing, rotatably connected to a radial projection 22, which may also be referred to as a collar, connected to the input shaft 10. The axial toothing ensures that feeler piston 20 of the torque sensor 15, which is also referred to as a torque sensor piston, can move relative to the input shaft 10 in the axial direction back and forth.

The sensor piston 20 defines, together with the input shaft 10, a torque sensor chamber 24, which is also referred to as a sensor chamber 24. Together with the radial projection 22, the sensor piston 20 defines a further torque sensor chamber 25, which is also referred to as a further sensor chamber 25. The first-mentioned sensor chamber 24 communicates via a connecting channel 28 with a pressure chamber 26, which is provided in the axial direction between the radial projection 22 of the input shaft 10 and the conical disk 12. The further sensor chamber 25 is connected via a connecting channel 30 with four apertures 31, 32, 33, 34 in connection. The apertures 31 to 34 are designed as single apertures or fixed apertures, that is, the aperture cross section of the apertures 31 to 34 is constant.

The connecting channel 30 extends in the form of a longitudinal bore partially through the

Input shaft 10. From the longitudinal bore four transverse bores extend radially outward, in each of which one of the apertures 31 to 34 is provided.

The diaphragms 31, 32 represent a first diaphragm pair which, depending on the axial position of the conical disk 12, is completely or partially or individually connectable to the pressure chamber 26. The two diaphragms 33 and 34 represent a second pair of diaphragms which, depending on the axial position of the conical disk 12, are connected completely or partially to the output side or to a pressure relief space, for example a tank. The output-side aperture 33 and 34 open between the travel plate 12 and the fixed disk, not shown, of the first pair of conical disks in a space in which the belt 14 is arranged.

An arrow 41 indicates in FIGS. 1 to 5 that the sensor chamber 24 is supplied with hydraulic medium as required by way of a hydraulic pump. A further arrow 42 indicates in FIGS. 1 to 5 that hydraulic medium can flow off via a control edge as a function of the axial position of the feeler piston 20 relative to the input shaft 10 via a transverse bore in the input shaft 10 into the pressure relief space or tank.

The diaphragms 31 to 34 are designed identically according to a further aspect of the invention. Thus, the apertures 31 to 34 all have the same diameter, for example 0.8 millimeters. In addition, the apertures 31 to 34, relative to a rotational axis 11 of the input shaft 10, are arranged the same in the radial direction. This provides the advantage that production-related batch spreads do not affect when the panels 31 to 34 are built batch-pure, since not the absolute aperture diameter determines the Anpressfehler, but only the relative differences of the aperture 31 to 34 in the associated input shaft 10 and the associated pulley , In addition, the identical design of the apertures 31 to 34 has the advantage that there is no risk of confusion, neither in production nor in assembly. By using identical diaphragms 31 to 34, moreover, their temperature dependence is compensated. FIG. 1 shows the underdrive operating stage, in which the two shutters 31, 32, which are also referred to as inlet orifices for the pressure chamber 26, are closed. At the same time, the two panels 33 and 34, which are also referred to as drain panels, are open. Thus, no pressure can build up in the Anpresskammer 26. In addition, indicated by the arrow 42 that the so-called changeover hole is open. This ensures, especially in dynamic driving situations, that no pressure can build up in the pressure chamber 26.

FIG. 2 shows the second operating stage with a transmission ratio of 1.8. The first panel 31 is partially opened. A volumetric flow flows through the first orifice 31 into the pressure chamber 26. The volumetric flow supplied via the connecting duct 30 is then distributed to the two completely open drain orifices 33 and 34.

FIG. 3 shows the third operating stage with a gear ratio of 1.0. The first aperture 31 and the fourth aperture 34 are open. The second and third shutters (32, 33) are closed. Thus, the volume flow supplied via the connecting channel 30 is distributed to the first orifice 31 and the fourth orifice 34. A first half of the volumetric flow passes via the first orifice 31 into the pressure chamber 26. The second half of the volumetric flow is discharged via the drain orifice 34.

FIG. 4 shows the fourth operating state with a transmission ratio of 0.75. The first panel 31 is fully open. The second panel 32 is partially open. The third panel 33 is closed and the fourth panel 34 is partially opened. A larger part of the volume flow supplied through the connecting channel 30 passes through the orifices 31 and 32 into the pressure chamber 26. A smaller part of the volume flow is discharged via the drainage orifice 34.

FIG. 5 shows the fifth operating state with a transmission ratio of 0.6. The two inlet apertures 31, 32 are open. The two drain panels 33 and 34 are closed. Thus, the pressure in the pressure chamber 26 is equal to the pressure in the other sensor chamber 25. Therefore, the torque sensor 15 behaves like a conventional two-stage torque sensor in the overdrive operating stage. Overdrive means, among other things, overdrive or low gear. Underdrive means analog crawl. The apertures 31 to 34 are preferably designed so that they come as close as possible to ideal apertures. In addition, the apertures 31 to 34 in the immediate vicinity of each other, so as close to each other, placed in the input shaft 10. This ensures that possibly existing temperature effects on all four panels 31 to 34 have the same effect.

List of references Cone pulley

symbol

first conical disk set

second conical disc set

arrow

endless

input shaft

axis of rotation

conical disk

endless

torque sensor

support ring

rolling elements

sensor piston

radial approach

Torque sensing chamber

further torque sensor chamber

Anpresskammer

connecting channel

cover

arrow

Claims

claims

1. Hydraulic system for driving a continuously variable conical-pulley belt drive (1), with two of a belt (14) looped conical disk pairs, each comprising two conical disks, one of which is axially displaceable in dependence on the pressure in an associated pressure chamber (26) and a torque sensor (15) including a torque sensing chamber (24) connected to a source of hydraulic power and communicating with at least one of the apply chambers (26) and another torque sensing chamber (25) for an underdrive operation stage or an overdrive operating stage of the conical-pulley transmission (1), characterized in that the hydraulic system comprises at least three fixed orifices (31-34) for providing, in addition to the underdrive operation stage or the overdrive operation stage, at least one further operation stage of the conical disc Wrap-around gearbox (1).

2. Hydraulic system according to claim 1, characterized in that the hydraulic system comprises four fixed orifices (31-34), in addition to the underdrive operating stage or the overdrive operating stage to represent at least two further operating stages of the conical disk-belt drive (1).

3. Hydraulic system according to one of the preceding claims, characterized in that the hydraulic system comprises four fixed apertures (31-34) to represent a total of five operating stages of the conical-pulley belt transmission (1).

4. Hydraulic system according to one of the preceding claims, characterized in that the fixed shutters (31-34) connected in parallel, arranged relatively close to each other and / or executed identically.

5. Hydraulic system according to one of the preceding claims, characterized in that the fixed orifices (31-34) in an input shaft (10) of the conical-pulley (1) are arranged and the axial position of a on the input shaft (10) displaceable deflector (12) of a first conical disk set (3) are switched on or off.

6. Hydraulic system according to one of the preceding claims, characterized in that in a first operating state, a first (31) and a second (32) diaphragm closed and a third (33) and a fourth (34) diaphragm, at least partially, are opened.

7. Hydraulic system according to claim 6, characterized in that in a second operating state, the second diaphragm (32) closed and the first (31), third (33) and fourth (34) diaphragm, at least partially, are open.

8. A hydraulic system according to claim 7, characterized in that in a third operating state, the second (32) and third (33) diaphragm closed and the first (31) and fourth (34) diaphragm, at least partially, are open.

9. Hydraulic system according to claim 8, characterized in that in a fourth operating state, the third diaphragm (33) closed and the first (31), second (32) and fourth (34) diaphragm, at least partially, are open.

10. Hydraulic system according to claim 9, characterized in that in a fifth operating state, the first (31) and second (32) diaphragm, at least partially, opened and the third (33) and fourth (34) diaphragm are closed.