DE102015215604A1 - Continuously variable transmission (CVT) with electronic torque sensor, drivetrain and method of controlling a continuously variable transmission - Google Patents

Abstract

The invention relates to a continuously variable transmission (1) for a motor vehicle, with axially movable discs (3, 4) of a drive disc pair (2) and axially movable discs (6, 7) of a driven disc pair (5), wherein between the respective two Discs (3, 4, 6, 7) of the drive disk pair (2) and the driven pulley pair (5) einklemmbares endless Umschlingungsmittel (8) can be used, wherein the pair of drive pulleys (2) causing a clamping first Anpresskammer (9) for receiving hydraulic fluid is associated with the driven pulley pair (5) a second Anpresskammer causing the clamping (10) for receiving hydraulic fluid, and the drive disc pair (2) is associated with a first adjustment chamber (11) for adjusting the axial distance of the local discs (6, 7) , and the output disc pair (5) is associated with a second adjustment chamber (12) for adjusting the axial distance of the local discs (11, 12) , wherein the adjusting and Anpresskammern (9, 10, 11, 12) at least via a pumping device (20) are supplied with hydraulic fluid, and at least from the adjustment chambers (11, 12) targeted a hydraulic fluid drainage enabling adjusting device (24) is inserted in that, depending on a torque present at the pair of drive disks (2), which is detectable by a torque-sensing unit (14), it controls the hydraulic fluid discharge or optionally in the inflow, the torque-sensing unit (14) being designed as an electrical device interposed a computing unit (26) for torque-dependent actuation of the adjusting device (24) is designed. The invention also relates to a drive train with such a transmission and a method for controlling or regulating a continuously variable transmission (1), comprising a first step of electrically detecting a torque on a pair of drive disks (5) and the second step of opening based on this information or Closing of an electrical adjusting device (24) for increasing or decreasing a pressure in two Anpresskammern (9, 10).

Description

The invention relates to a continuously variable adjustable transmission for a motor vehicle, such as a car, a truck or other commercial vehicle, with axially movable discs of a pair of drive disks and axially movable discs of a driven disc pair, wherein between the respective two discs of the drive disc pair and the driven pulley pair einklemmbares endless belt / endless traction means, such as a chain or a belt, is present, so the pairs of disks together torque-transmitting connects, wherein the drive disk pair is assigned a clamping of the belt causing the first Anpresskammer for receiving hydraulic fluid and the driven pulley pair causing a terminal second Anpresskammer for receiving is assigned by hydraulic means, and the drive disk pair is associated with a first adjustment chamber for adjusting the axial distance of the local disks, and the driven pulley npaar a second adjustment chamber for adjusting the axial distance of the local discs is assigned, further, the two adjustment chambers and the two output chambers are supplied at least via a pumping means with hydraulic means, and at least one of the adjustment specifically targeted a hydraulic fluid drain or a hydraulic fluid supply enabling setting device is used in that it controls or even regulates the hydraulic agent outflow or the hydraulic fluid inflow in dependence on a torque present at the drive disk pair which is detectable by a torque-sensing unit.

Continuously variable transmission (CVT) transmissions are already known from the prior art. For example, the EP 0 208 398 B1 a hydraulic control system for a continuously variable transmission with an input shaft, hydraulically adjustable, axially movable pulley elements that determine an adjustable ratio belt mechanism, and an output shaft, the control system comprising: a fluid pressure source; first valve means connected to the source for supplying control fluid to one of the adjustable pulley elements, the control fluid acting on the first valve means for transmitting a force thereon; second valve means having a connection to a torque-sensing means and a fluid connection to the first valve means; and feedback means for applying a force proportional to the axial position of the one pulley element to the first valve means in addition to the force exerted by the control fluid. It is particularly emphasized in that document that the control system includes: a toothed gear assembly for transmitting torque from the pulley mechanism to the output shaft, wherein the torque sensing means is operatively connected to a non-rotatable member of the toothed gear assembly and the transmission of a through the gear train transmitting torque proportional force causes a servomotor to be operatively connected to the torque sensing means; further wherein the second valve means is connected to the torque sensing means and operable upon a change in torque transmission for distributing a fluid pressure signal from the source to the servo motor; further wherein the servomotor, in response to the pressurized fluid, balances the force on the torque sensing means and interrupts the fluid distribution thereto; and further comprising conducting means for directing the fluid pressure signal from the second valve means to the first valve means.

From the DE 197 50 722 A1 is also known a drive arrangement for a motor vehicle, namely such, with a drive shaft of a drive unit, an output shaft and arranged between the drive shaft and the output shaft continuously variable transmission with an input shaft and an output shaft. It is particularly found that the input shaft of the continuously variable transmission is connected via a starting element and a first torque sensor to the drive shaft, wherein the continuously variable transmission is arranged such that the respective axes of rotation of the drive shaft and input shaft are aligned.

Also, the torque monitoring system disclosure of DE 10 2006 056 692 A1 is interesting. There, a torque monitoring system and method for monitoring torque and a machine are disclosed. A torque monitoring system receives torque data from a drive shaft for use by engine-transmission or other vehicle controllers. The torque monitoring system uses a structural member to hydraulically connect a driving member to a driven member. A pressure gauge is operatively connected to a fluid chamber in the structural member by which the driving member drives the driven member. The pressure gauge measures a pressure level in the chamber. The amount of torque transmitted from the driving element to the driven element is in direct linear relationship to the measured pressure. In one embodiment, the pressure measuring device is a surface wave sensor in contact with the hydraulic fluid, which is a sensor signal, ie, a signal having a value that is the measured pressure and thus corresponds to the torque, wirelessly transmits to the controller.

A similar prior art is also from the DE 42 34 294 A1 known. There is a continuously variable conical pulley with two mutually adjustable conical pulley pairs, a drive and a driven side cone pulley pair, disclosed, wherein at least one of the conical pulley pairs by means of a torque sensor for clamping the belt is acted upon, the torque sensor rolling elements, such as balls, has, with Abwälzflächen work together, which generate torque and translation-dependent clamping forces. So there are just from that latter document known hydraulic-mechanical torque sensor.

Continuously variable transmissions with electronic pressure or mechanical torque sensors reflect the state of the art. The torque sensor represents a considerable mechanical effort and is difficult to integrate in so-called "front-transverse" applications due to the space requirement. Advantages of the torque sensor in conventional design, but so far are an exact mechanical detection of the input torque and its direct transfer into a contact pressure. Also, it has been advantageous to be able to use such hydraulic-mechanical torque sensor in the most widespread on the market systems easy.

Usually, the provision of the hydraulic pressure for the contact pressure and adjustment by a mechanically driven pump so far done so far.

However, a "down-sizing", ie downsizing of internal combustion engines / engines, recently causes a qualitative deterioration of the torque signal, which originates from the internal combustion engine / the engine. By a suitable device, the torque at the transmission input but should be able to be sensed. This should make it possible to capture the input torque more precisely and adjust the contact pressure accordingly. It is desirable that the torque signal be further processed to be used to drive a pressure control valve.

It is the object of the invention to make better use of the installation space, to provide a cost-effective solution, and to have more possibilities for a sensible use. In principle, however, the disadvantages of the prior art in particular should be remedied or at least mitigated.

This object is achieved in that the torque sensor is designed as an electrical device or is designed as an electronic device, which is designed with the interposition of a computing unit for torque-dependent actuation / actuation of the position direction.

Advantageous embodiments are claimed in the subclaims and are explained in more detail below.

Thus, it is advantageous if the adjusting device is designed as a solenoid valve. Precise rules or taxes can then be achieved.

Further, it is advantageous if the adjusting device for opening and / or closing a drain opening or optionally in the inflow, which does not have to be digital, but continuously, in a fluid-connected with two Anpresskammern Klemmbewirkleitung / hydraulic medium line is designed.

In order to allow easier production, it is advantageous if the drain opening is designed as a drain hole.

It has also been found to be advantageous if the torque-sensing unit includes an electrical sensor, such as one or more strain gauges. Accurate results are then the result.

Alternatively or additionally, it is also possible that the electrical sensor is designed for transferring the data to a telemetric transmission device and / or is vapor-deposited on a non-rotatably connected to a disc of the drive disk pair contact area. An outward lead of the data and information can then be simplified and / or a permanently valid results supplying solution can be achieved.

If the pump device includes a mechanically coupled with a transmission input shaft / coupled main pump or includes a decoupled from the transmission input shaft electric motor driven / driven main pump, it can be specifically caused caused independent of a crankshaft power actuation. Furthermore, it is advantageous if the pump device includes a hydraulic medium to both displacement chambers suitable for spreader / electrically driven / driven auxiliary pump or includes two hydraulic fluid to each adjusting chamber for the purpose of suitable / spending electrically driven / driven by-pumps. It would thereby created a double piston system, the offers the advantage that the contact pressure and the adjustment can be hydraulically separated from each other.

The result is an advantageous embodiment, when the pumping device includes a pump that is designed / prepared for the active extraction of hydraulic fluid from one or more chambers of the pressing and / or Verstellkammern. In this way, a quick adjustment can be achieved.

If each adjustment chamber is assigned a secondary pump, which is in each case connected to its own electric motor, then a "power-on-demand" solution can be achieved not only for the one adjustment chamber, but for both adjustment chambers. It is also possible to raise the pressure level for both adjustment chambers when both pumps are activated. This is especially useful for emergency situations to increase the contact pressure.

The invention ultimately also relates to a drive train of a motor vehicle, with a transmission in the manner according to the invention.

However, the invention also relates to a method for controlling a continuously variable transmission (CVT), comprising a first step of electrically detecting a torque on a drive disk pair and the second step based on this information of opening or closing an electric actuator for raising or lowering one Pressure in two pressure chambers.

A further development is that at least one electrically driven pump is controlled or regulated based on the information obtained in the first step.

The presented solution makes it possible for the main pump to work satisfactorily even at low temperatures, since it is generously sized. Of course, it is also designed to compensate for leakage.

Of course, the secondary pumps are designed to compensate for leakage, but they should not be over-sized to be designed for low temperatures. Because of the changed viscosity, lower temperatures cause a poorer flowability. Only the main pump must be dimensioned so large that even at low temperatures enough clamping force can be provided. The secondary pumps need not be provided with such great security, since the main pump in operation leads to a heating of the hydraulic fluid, such as oil / mineral oil, and so after a short time can be effected again via the secondary pumps an adjustment. The adjustment of "Overdrive" to "Underdrive" is thereby quickly re-feasible even in the most difficult situations and environmental conditions. The operational safety is increased.

In other words, the invention also relates to a CVT transmission with an electronic torque sensor and an electrically driven pump. There are so far mainly CVT arrangements with hydraulic-mechanical (rotary) torque sensor known. The derivation of the torque from the engine control unit and other torque sensors are also known. However, the down-sizing of the engines, as explained, but a qualitative deterioration of the torque signal from the engine. Also, the hydraulic-mechanical torque sensor requires a relatively large amount of space, which is not available for "front-transverse" applications. Thus, there is now proposed a single or dual piston CVT system having an electronic sensor for accurately detecting input torque at the transmission input shaft. Thus, the contact pressure can be set accurately and an overpressure of the system can be avoided. This increases efficiency. In conjunction with the double piston system, it is additionally possible to represent the required adjustment by means of one or two electrically driven pumps in a "power-on-demand" system. As a result, the overall efficiency of the transmission can be further improved. Hybridization requires an increase of the on-board voltages in the medium term and thus also enables the electric drive of the pumps.

The torque signal is converted in an ECU into a signal for driving the pressure regulating valve.

Although the efficiency of the CVT transmission is lower than that of conventional automatic step machines, which is due to the high pressures required to press and adjust the system, this inconvenience is more than compensated for by the stepless change in the operating point of the engine. The required pressures and volume flows are no longer necessarily provided by permanently mechanically driven pumps. An improvement is being achieved here. In critical driving situations, when, for example, a shock from the wheel side is to be expected, electronically controlled systems must be subjected to additional safety factors. This is possible now.

The invention will be explained in more detail with the aid of a drawing. Show it:

1 a CVT with mechanical torque sensor, but already two different pumps, one pump supplying the pressure chambers and the other pump supplying the two displacement chambers with hydraulic fluid / oil,

2 a special embodiment in which a single mechanical pump is used for the two Anpresskammern and a single electrically driven pump for the two Verstellkammern is used, with an electronic torque sensor whose information is passed to a computing unit / ECU and then to an adjusting device for closing a drain hole is forwarded, and

3 a further embodiment in which, however, instead of only a single electronic pump for the adjustment chambers two separate, separate electronically driven pumps are used to differently than in the embodiment of 2 be able to supply the two pressure chambers separately from each other.

The figures are merely schematic in nature and are only for the understanding of the invention. The same elements are provided with the same reference numerals.

In 1 is a continuously variable transmission 1 shown. It is intended for use in a drive train of a motor vehicle, such as a car, a truck or other commercial vehicle.

The gear 1 has a drive disk pair 2 on, the two cone-shaped discs 3 and 4 includes. Furthermore, a pair of driven pulleys 5 available, the two slices 6 and 7 having. The disks 6 and 7 are similar to the discs 3 and 4 cone-shaped. The sloping surfaces of the discs 3 and 4 as well as the discs 6 and 7 are aligned with each other on a pair of discs. At this is a wrap / endless draw 8th clamped.

In the illustrated variant is the belt / the endless traction means 8th in an "underdrive" position. The drive disk pair 2 is a first pressure chamber 9 assigned. The driven pulley pair 5 is a second pressure chamber 10 assigned. The pressure chamber 1 connected in series or the Anpresskammer 10 connected in series, there is a first adjustment chamber 11 or a second adjustment chamber 12 , The two pressure chambers 9 and 10 are with a Klemmbewirkleitung 13 for conducting hydraulic fluid such as (mineral) oil. Strictly speaking, the Klemmbewirkleitung 13 several sections, so that a certain section, the first adjustment chamber 1 contacted and a certain other section the second adjustment chamber 2 contacted. But the two sections open together into a main line leading to a torque sensor or a torque sensor 14 leads.

In the variant of 1 is the torque-sensing unit 14 a hydraulic-mechanical sensing device, which is a primary pulley 15 and a secondary disc 16 between which a rolling element 17 , namely a ball, is arranged. A change to an electronic torque sensor 14 but is possible and useful.

Depending on how far the secondary pulley 16 to the primary disk 15 is twisted, the effect between the two discs 14 and 16 existing rolling elements 17 an axial displacement of the secondary pulley 16 so that a drain opening 18 infinitely more or less closed / opened. The secondary disc 16 , which is formed like a piston, so is in the direction of a shift arrow 19 shifted depending on the torque.

To the Klemmbewirkleitung 13 is a pumping device 20 connected. In fact, it's a main pump 21 to the Klemmbewirkleitung 13 connected. This main pump 21 is a mechanically connected / driven pump, which thus receives its energy through a mechanical coupling with, for example, a transmission input shaft. A secondary pump 22 may be configured as a comparable mechanical pump, or desirably configured as an electrically driven pump. The sub pump 23 is in a pipe system 23 integrated, with two strands each to one of the two Verstellkammern 11 and 12 leads.

In the embodiment of 2 is a special adjusting device 24 used as a solenoid valve 25 is trained. This solenoid valve receives the control or control commands from a computing unit / ECU 26 , The ECU 26 receives the necessary output data from a torque-sensing unit 14 that has an electrical sensor 27 contains. The connection of the electrical sensor 27 with the arithmetic unit / ECU 26 with the solenoid valve 25 via electrical lines 28 ,

The sub pump 22 is designed as an electrically driven pump, which is an electric motor 29 contains or is associated with it. The electric motor 29 is about a wave 30 coupled. The main pump 21 corresponds to the main pump 21 , as regards the 1 already described, but it is designed a little smaller. The main pump 21 as used in the embodiment of 3 has been used is designed accordingly. In the embodiment of 3 are two secondary pumps 22 Used together with the main pump 21 the pumping device 20 form.

LIST OF REFERENCE NUMBERS

1

 continuously variable transmission / CVT (continuously variable transmission)

2

 Sheave pair

3

 Washers of the drive disk pair

4

 Washers of the drive disk pair

5

 Output disk pair

6

 Discs of the driven pulley pair

7

 Discs of the driven pulley pair

8th

 Wraparound / continuous traction

9

 first pressure chamber

10

 second pressure chamber

11

 first adjustment chamber

12

 second adjustment chamber

13

 Klemmbewirkleitung

14

 Drehmomentsensiereinheit

15

 primary disc

16

 secondary disc

17

 rolling elements

18

 drain hole

19

 displacement arrow

20

 pumping device

21

 main pump

22

 In addition to pump

23

 line system

24

 setting device

25

 Solenoid valve

26

 Butterfly / ECU

27

 electrical sensor

28

 electrical line

29

 electric motor

30

 wave

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0208398 B1 [0002]
• DE 19750722 A1 [0003]
• DE 102006056692 A1 [0004]
• DE 4234294 A1 [0005]

Claims (10)

Infinitely variable transmission ( 1 ) for a motor vehicle, with axially movable discs ( 3 . 4 ) of a drive disk pair ( 2 ) and axially movable discs ( 6 . 7 ) of a driven pulley pair ( 5 ), whereby between the respective two disks ( 3 . 4 . 6 . 7 ) of the drive disk pair ( 2 ) and the driven pulley pair ( 5 ) a clampable endless looping means ( 8th ), wherein the drive disk pair ( 2 ) a clamping chamber causing the first ( 9 ) is assigned to receive hydraulic fluid and the driven pulley pair ( 5 ) a second pressing chamber causing the clamping ( 10 ) is assigned to receive hydraulic fluid, and the drive disc pair ( 2 ) a first adjustment chamber ( 11 ) for adjusting the axial distance of the local disks ( 6 . 7 ), and the driven pulley pair ( 5 ) a second adjustment chamber ( 12 ) for adjusting the axial distance of the local disks ( 11 . 12 ), wherein the adjusting and pressing chambers ( 9 . 10 . 11 . 12 ) at least via a pumping device ( 20 ) are supplied with hydraulic fluid, and at least one of the adjustment chambers ( 11 . 12 ) specifically a hydraulic fluid drain or a hydraulic fluid inflow enabling adjusting device ( 24 ) is inserted in such a way that it depends on one on the drive disk pair ( 2 ) present torque via a torque sensing unit ( 14 ), the hydraulic agent drain or the hydraulic fluid inlet controls, characterized in that the torque-sensing unit ( 14 ) is formed as an electrical device which, with the interposition of a computing unit ( 26 ) for the torque-dependent actuation of the actuating device ( 24 ) is designed. Transmission ( 1 ) according to claim 1, characterized in that the adjusting device ( 24 ) as a solenoid valve ( 25 ) is trained. Transmission ( 1 ) according to claim 1 or 2, characterized in that the adjusting device ( 24 ) for opening and / or closing a discharge opening ( 18 ) or alternatively in the inflow in one with the two Anpresskammern ( 9 . 10 ) fluid-conductively connected Klemmbewirkleitung ( 13 ) is designed. Transmission ( 1 ) according to one of claims 1 to 3, characterized in that the torque-sensing unit ( 14 ) an electrical sensor ( 27 ) contains. Transmission ( 1 ) according to one of claims 1 to 4, characterized in that the pumping device ( 20 ) a mechanically coupled to a transmission input shaft main pump ( 21 ) or one of the transmission input shaft decoupled electric motor driven main pump ( 21 ) includes. Transmission ( 1 ) according to one of claims 1 to 5, characterized in that the pumping device ( 20 ) a for driving hydraulic medium to both adjustment chambers suitable electrically driven auxiliary pump ( 22 ) includes or two for the introduction of hydraulic fluid to each an adjustment chamber ( 11 . 12 ) suitable electrically driven auxiliary pumps ( 22 ) includes. Transmission ( 1 ) according to one of claims 1 to 6, characterized in that the pumping device ( 20 ) includes a pump for active extraction of hydraulic fluid from one or more chambers of the pressing and / or Verstellkammern ( 9 . 10 . 11 . 12 ) is designed. Transmission ( 1 ) according to claim 6 or 7, characterized in that each adjustment chamber ( 11 . 12 ) a secondary pump ( 22 ), each with its own electric motor ( 29 ) connected is. Drive train of a motor vehicle with a transmission ( 1 ) according to any one of the preceding claims. Method for controlling or regulating a continuously variable transmission ( 1 ), with a first step of electrically detecting a torque on a drive disk pair ( 5 ) and based on this information second step of opening or closing an electric actuator ( 24 ) for increasing or decreasing a pressure in two contact chambers ( 9 . 10 ).

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