• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A hydraulic control circuit (1) for controlling a CVT (20) comprising a primary and a secondary pulley (21, 23) mechanically coupled by a flexible endless element (25). The hydraulic control circuit includes a feed pump (10; 10 ') to supply hydraulic fluid with a first fluid pressure value (P1), a bi-directional lift pump (12) coupled via a first and a second hydraulic branch (13, 14) to a respective pulley actuator. The bi-directional lift pump is adjustable to move hydraulic fluid in both directions between the first and second hydraulic branches. A selection valve (15) controllably couples the feed pump to the first or second hydraulic branch. The hydraulic control circuit controls the selector valve to select the hydraulic branch of the pulley actuator indicated as the one with the smallest running radius in the prevailing operating state of the CVT.
    公开号:BE1026582A9
    申请号:E20185610
    申请日:2018-08-31
    公开日:2020-06-03
    发明作者:Buul Wouter Benedictus Van；Leeuwen Dennis Van；Rooij Jacobus Hubertus Maria Van
    申请人:Punch Powertrain Nv；
    IPC主号:
    专利说明:

    A hydraulic control circuit for a continuously variable transmission, a continuously variable transmission and a method for controlling the clamping forces of a continuously variable transmission.
    BACKGROUND
    The present invention relates to a hydraulic control circuit for a continuously variable transmission (also referred to as CVT), a continuously variable transmission and a method for controlling the transmission ratio of a continuously variable transmission and the clamp level for a transmission element of the continuously variable transmission.
    A continuously variable transmission for providing a continuously variable transmission ratio between an input shaft and an output shaft is described in NL 1009954. The continuously variable transmission is provided with a first pulley with an input shaft and a second pulley with an output shaft, a flexible element that mechanically couples the pulleys and a hydraulic control circuit for hydraulic control of the pulleys. A first and a second pump, driven by an electric motor, pressurize a hydraulic fluid, with which the hydraulic control circuit activates the first and second pulleys to enable a slip-free transmission with a desired transmission ratio between the input shaft and the output shaft. The first pump serves as a feed pump and the second pump as a feed pump. A selection valve is provided that responds to the pressures present in the hydraulic branches to the pulley actuators to cause the feed pump to supply a flow of hydraulic fluid at an initial fluid pressure sufficient to operate the pulley with the lowest requirement pressure to ensure slip-free operation of the CVT. The feed pump receives and supplies hydraulic fluid from the feed pump at the first pressure
    BE2018 / 5610 hydraulic fluid with a second pressure to enable control of the other of the pulleys.
    Slipping of the flexible element results in a loss of efficiency and can further lead to wear and breakage of the flexible element. To prevent slip of the flexible element, a fluid pressure that exceeds the minimum required fluid pressure by a safety margin is used to control the pulleys. This sets the clamping force to a value higher than the clamping force that would theoretically be required for slip-free operation to account for uncertainties in physical parameters and external disturbances of the variator system. It is a drawback of the known transmission that the selection valve adjustment is not reliable when its transmission ratio is within a central range. Therefore, to avoid the risk of variator slipping, the safety margin in the central range should be relatively high to account for this uncertainty. However, this also reduces the efficiency of the transmission.
    RESUME
    It is an object of the present invention to provide measures that increase transmission efficiency without increasing the risk of slip of the flexible element.
    To this end, a hydraulic control circuit according to claim 1 is provided. In the hydraulic control circuit according to claim 1, the hydraulic pressure with which the pulley actuators are controlled depends on determining which of the pulleys has the smallest running radius.
    This measure is based on the observation that the slip risk is greatest for the pulley with the smallest running radius. Accordingly, the clamping level for this pulley must be most accurately controlled. By controlling the hydraulic pressure with which the pulley actuators are controlled in a manner which depends on which
    BE2018 / 5610 of the pulleys is determined to have the smallest running radius, the hydraulic control circuit will by definition supply the feed pump fluid pressure to the actuator of the pulley most prone to slip, even if different piston surfaces were used to the first and adjust the second pulley. The clamping force applied with the actuator of the second pulley depends on the clamping force ratio, which must be estimated, thereby introducing additional uncertainty. Since this uncertainty relates to the pulley with the larger running radius, which is less critical, this is not a serious problem. However, if the pulley with the smallest running radius is not directly controlled by the fluid pressure, it would be necessary to increase the safety margin, which would require higher operating pressures on average. By removing this uncertainty, the safety margin for the clamping force can be set to a lower value. Accordingly, better transmission efficiency is achieved in that generally lower hydraulic pressures are sufficient to ensure slip-free operation of the variator.
    In one embodiment, the hydraulic control circuit is further configured to account for an expected change in state when selecting the destination for supplying the hydraulic fluid with the first pressure. For example, when controlling a change of transmission ratio assuming a condition where the pulleys have an equal running radius, the hydraulic control circuit is arranged to supply hydraulic fluid of the first pressure to the pulley actuator which is predicted to be after said change has the smallest running radius.
    BRIEF DESCRIPTION OF THE DRAWINGS
    These and other aspects are described in more detail with reference to the drawings.
    In it shows:
    BE2018 / 5610
    Fig. 1 schematically a drivetrain;
    Fig. 2 a first embodiment of a hydraulic control circuit;
    Fig. 3 a second embodiment of a hydraulic control circuit;
    Fig. 4 a third embodiment of a hydraulic control circuit;
    Fig. 5A, 5B show exemplary elements for use in the hydraulic control circuit.
    DESCRIPTION OF THE EMBODIMENTS
    Fig. 1 schematically shows, for example, a drivetrain 2 in a vehicle for transferring power from a power source MOT, such as a combustion engine or an electric motor, to wheels WH of the vehicle. The drivetrain includes a continuously variable transmission 20. In the embodiment shown, the drivetrain 2 includes further transmission elements, here a torque converter / lock clutch (TC / LUC) TC, a forward-neutral reverse-clutch planetary gear set (DNR), a fixed gear FD and a differential DF. The torque / converter clutch torque TC connects an output shaft from the MOT motor to the forward-neutral-reverse-clutch planetary gear set DNR, with an adjustable slip ratio and a correlated torque ratio, ie the ratio of the output torque to the output torque. torque received at the input from the MOT motor. The DNR planetary gear set is provided to couple the torque converter transducer / lock clutch TC to the CVT 20. The DNR clutch can be controlled to adopt one of a drive mode D that corresponds to the vehicle driving in a forward direction. reverse mode R where the vehicle is driven to the rear and a neutral mode in which it keeps the CVT 20 disconnected from the TC / LUC TC. The CVT 20 carries energy supplied via the TC / LUC and the DNR coupling from the MOT motor through the fixed transmission FD and the differential DF to the wheels WH, with a transmission ratio that can be taken from a continuous range
    BE2018 / 5610 selected. In other embodiments of the drivetrain, transmission elements may be in a different order. In still other embodiments, one or more of the further transmission elements may be absent and / or other further transmission elements may be included. Although in this example the CVT is shown as a drivetrain, its use is not limited to this application. Other applications are conceivable in which the presence of a continuously variable transmission between an input shaft and an output shaft is advantageous, for example as a transmission element between the turbine of a windmill and an electric power generator.
    A hydraulic control circuit 1 is provided to hydraulically control the setting of the CVT 20 and optional further transmission elements. The hydraulic control circuit 1 is in turn controlled by control signals from an electronic transmission control unit TCU 3, for example a general purpose processor, by special hardware, or by a programmable signal processor. A motor control unit ECU for controlling the power source is further provided, which is coupled via a bus, e.g. a CAN bus to the TCU controller. In analogy to the TCU, this controller can also be, for example, a general purpose processor, special hardware or a programmable signal processor. In another embodiment, a single control unit serving as an ECU and a TCU may be provided.
    Fig. 2 shows a first embodiment of a hydraulic control circuit 1 for controlling a continuously variable transmission 20. For clarity, FIG. 1 only the CVT 20. Typically, the CVT 20 forms part of a drivetrain 2, which may also include other transmission elements, for example as described with reference to FIG. 1.
    As shown in FIG. 2, the CVT 20 includes a primary pulley 21 with an input shaft 22 driven by a power source. The power source is, for example, a motor, e.g. MOT (Figure 1) or a windmill turbine. The CVT 20 has a secondary pulley 23 with a
    BE2018 / 5610 output shaft 24 which is to drive a target, e.g. wheels WH (see figure 1) of a vehicle or an electric power generator. The CVT 20 further includes an endless, flexible transmission element 25 wrapped around the pulleys 21, 23 which mechanically couples the pulleys 21, 23. The pulleys 21, 23 each comprise an axially fixed cone disc 21a, respectively. 23a and an axially displaceable cone disk 21b and 23b, the last disks being axially controllable with a respective hydraulic actuator 26, 27 to set a transmission ratio between the input shaft 22 and the output shaft 24. Typically, the actuators 26, 27 are positioned crosswise as shown in FIGS. 2, 3 and 5. The hydraulic control circuit 1 is adapted to control a running radius R21, R23 of each of the pulleys, by driving the respective actuators with a hydraulic fluid at a respective operating pressure value P26, P27. Thus, a transmission ratio i can be set to a desired value R23 / R21.
    The hydraulic control circuit includes a feed pump 10 with an output 11 to supply hydraulic fluid with a first fluid pressure value Pi. The hydraulic control circuit also includes a bi-directional lift pump 12, which is coupled via a hydraulic branch 13 to the first hydraulic actuator 26 and via the hydraulic branch 14 to the second hydraulic actuator 27. The bi-directional lift pump 12 is controllable with a control signal S12 of control unit 3 to displace hydraulic fluid in any direction between the and the hydraulic branches 13, 14. The hydraulic control circuit 1 further comprises a selection valve 15 which couples the output 11 of the feed pump 10 to the hydraulic branch 13 or to the hydraulic branch 14 in response to a control signal S15 from the control unit 3. In an operational state, the control unit 3 controls the selection valve 15 to select the hydraulic branch coupled to the pulley actuator indicated as the one with the smallest running radius in that operational state.
    In the illustrated embodiment, the running radii R21, R23 of the pulleys 21, 23 are indicated by input signals S21, S23. These input signals can be provided by sensors provided with
    BE2018 / 5610 the pulleys, S21, S23, for example, represent input signals from sensors
    51, 53 (see Figure 5A) which measure the axial positions of the axially displaceable cone discs 21b, 23b. The running radii R21, R23 are linearly geometrically defined by these axial positions. Since the pulleys 21, 23 are coupled by the transmission element 25, the positions of the movable conical pulleys 21b, 23b are also interconnected geometrically. Thus, measuring only one of the axial positions of the cone discs 21b or 23b is sufficient to determine whether the transmission ratio is above or below a ratio i = 1, and thus sufficient to determine which pulley has the smallest running radius. For example, as shown in FIG. 5A, the logic element 55 receives the input signal S21 from the first sensor 51, indicative of the axial position of the axially displaceable conical disk 21b and uses this information to calculate the indication Imin, which indicates which of the pulleys 21, 23 has the smallest running radius . The second sensor 53 and its output signal are shown in dashed lines to clarify that the input signal S21 is sufficient to determine the indication Imin. Likewise, the indication Imin could only be calculated from the signal from the sensor 53. Nevertheless, it may be considered to use both sensor signals S21, S23, for example, as a way to detect a malfunction or to identify a transition region in which the individual sensor signals S21, S23 would result in different indications for Imin.
    As another example, shown in FIG. 5B, S21, S23 represent output signals from rotational speed sensors 61, 63. The pulley with the highest rotational speed is identified by logic unit 65 with signal Imin as the one with the smallest running radius. Equal rotational speed of the pulleys 21.23 will determine the speed ratio i = 1 and will indicate a change of the pulley with the smallest running radius.
    Alternatively, sensors can be provided that directly measure the running radius. Furthermore, the indication may be based on the estimated running radius, depending on the hydraulic pressures with which the
    BE2018 / 5610 actuators are driven. Also, different input signals indicative of the running radius can be combined to obtain a resulting indication of the pulley with the smallest running radius. For example, a speed sensor with a flexible element could be used in combination with a pulley speed sensor to determine the running radius.
    In the embodiment shown, it is indicated that the primary pulley 21 has the smallest running radius, and the selection valve 15 is controlled accordingly to couple the output 11 of the feed pump 10 to the hydraulic branch 13. Thereby, the actuator 26 of the primary pulley 21 is operated with a hydraulic pressure P26, equal to Pi, as supplied by the feed pump 10. With the feed pump 12, controlled to move the hydraulic fluid in the direction of the hydraulic branch 13 to branch 14 or vice versa, the actuator 27 is driven with a pressure P27.
    In the illustrated embodiment, the pressure P26, P27 exerted by the hydraulic fluid on the actuators 26, 27 is determined by the pumps 10 and 12. The controller 3 controls these pressures by energizing electric motors appropriately with drive signals S10, S12 10m, 12m for driving the pumps 10, 12. To this end, the electronic controller 3 may have means for pressure monitoring, for example a pressure sensor 16 which outputs a sensor signal Sie indicative of a pressure Pi monitored in branch 19. A pressure control facility is provided by the electronic controller 3 being able to control the operational status of the feed pump 10 with control signal S10 to set the pressure Pi to a desired value.
    Fig. 3 shows an operational state indicating that the secondary pulley 23 has the smallest running radius and that the selection valve 15 is controlled accordingly to couple the output 11 of the feed pump 10 with the hydraulic branch 14. Thereby, the actuator 27 of the pulley 23 operated with the hydraulic pressure P27 supplied by the feed pump 10, equal to Pi. With the feed pump 12
    BE2018 / 5610 controlled to move the hydraulic fluid in the direction of the hydraulic branch 14 to the hydraulic branch 13 or vice versa, the actuator 26 is operated with a pressure P26.
    By controlling the hydraulic pressure for operating the pulleys in a manner that depends on which of the pulleys is determined to have the smallest running radius, the hydraulic feed pump 10 directly delivers the driving pressure to the pulley most susceptible to slipping. the flexible element. This reduces the risk of slipping, which makes it possible to limit safety factors or to limit a clamping margin on the small pressure controlled by the feed pump. This significantly reduces the risk of shp and wear on the flexible element and increases the overall power transfer efficiency of the CVT.
    Fig. 4 shows an alternative arrangement. Parts therein corresponding to those in FIG. 2 and 3 have the same references. In contrast to the embodiment shown in FIG. 2, 3, the rotational speed of the feed pump 10 'is not independently controllable. The feed pump 10 'may, for example, be driven by the power source MOT, which cannot be controlled by the controller 3. This is, for example, the engine MOT driving a vehicle, and which is controlled by a special engine control unit ECU. In the embodiment shown, the output 11 'of the feed pump 10' feeds a branch 19 which provides an input of the selection valve 15. As in the embodiment of FIG. 2, 3, the electronic controller 3 controls a pressure Pi in the branch 19. Contrary to this previous embodiment, the electronic controller 3 maintains the hydraulic pressure in branch 19 with a control signal S17 driving an electronically controllable pressure control valve 17, also referred to as a pressure relief valve . The pressure control valve 17 serves as a pressure regulator in this embodiment.
    In addition, an autonomously operating safety valve 18 can be provided which can at least divert a flow of hydraulic fluid if the hydraulic pressure exceeds a safety threshold.
    BE2018 / 5610 The feed pump 10 'or other elements of the hydraulic circuit can have output to other branches that serve as an oil supply for clutch operation and for lubrication and cooling or for delivery to other hydraulic consumers. It will be apparent to those skilled in the art that elements presented in the drawings are only examples of a variety of suitable implementations. The controllable valve 15 could also be provided, for example, as a valve controllable in three or more separate steps or one that is proportionally controllable. It may further be considered to replace the valve 15 with a pair of independently controllable valves, one from the outlet 11 of the pump 10 to the hydraulic branch 13 and one from the outlet 11 of the pump 10 to the hydraulic branch 14. These valves also can be simple open / close valves or valves controllable in three or more separate steps or proportionally controllable valves.
    In the claims, the word comprising does not exclude other elements or steps, and the indefinite article a or a does not exclude a plural. A single component or other unit can perform the functions of various parts mentioned in the claims. The mere fact that certain measures are described in mutually different claims does not exclude the possibility of a favorable combination of these measures. References in the claims should not be interpreted as limiting the scope of protection.
    权利要求:
    Claims (13)
    [1]
    A hydraulic control circuit (1) for controlling a continuously variable transmission (CVT, 20) comprising a primary pulley (21) with an input shaft (22) and a second pulley (23) with an output shaft (24), as well as an endless, flexible transmission element (25) that mechanically couples the pulleys, the pulleys being axially controllable with a respective hydraulic actuator (26, 27) to set a transmission ratio between the input shaft and the output shaft and a clamp level for the transmission element, wherein the hydraulic control circuit is arranged to control a running radius of each of the pulleys, by driving the respective actuators with a hydraulic fluid at a respective operating pressure value, the hydraulic control circuit at least comprising a feed pump (10; 10 ') with an outlet (11, 11') for supplying hydraulic fluid at a first fluid pressure value (Pi), a bi-directional lift pump (12) coupled via a first hydraulic branch (13) with a first of the hydraulic actuators and via a second hydraulic branch (14) with a second of the hydraulic actuators, the bi-directional feed pump being adjustable to control hydraulic fluid in any direction between the first and the second hydraulic branch, the hydraulic control circuit further comprising a selection valve (15) for controllably coupling the feed pump output to one of the first and second hydraulic branches, characterized in that in an operational state the selection valve is controlled to select the hydraulic branch associated with the pulley actuator indicated to have the smallest running radius in that operating condition.
    [2]
    The hydraulic control circuit according to claim 1, wherein the hydraulic control circuit comprises a logic unit (55) that uses an indication (S21) for an axial position of a cone disk (21b) that part
    BE2018 / 5610 includes a pulley (21) to determine which of the primary pulley (21) and the secondary pulley (22) has the smallest running radius.
    [3]
    The hydraulic control circuit according to claim 1 or 2, wherein the hydraulic control circuit comprises a logic unit (65) which identifies the pulley with the highest rotational speed of the primary pulley and the secondary pulley as the pulley with the smallest running radius.
    [4]
    The hydraulic control circuit according to claim 1, 2 or 3, characterized in that a sensor is provided for measuring a fluid pressure supplied to the actuator of the pulley with the smallest running radius.
    [5]
    The hydraulic control circuit according to any one of the preceding claims, characterized in that a pressure control device is provided which is arranged to control a value for the first fluid pressure based on one or more of: a pressure value indicated by the pressure sensor and vehicle parameters, such as transmission parameters such as desired pulley clamping force, belt slip, endless flexible transmission element speed, torque, vehicle speed, transmission ratio, and selection valve condition.
    [6]
    The hydraulic control circuit according to any one of the preceding claims, characterized in that the feed pump is arranged to displace a hydraulic fluid between the selected hydraulic branch and another hydraulic branch.
    [7]
    The hydraulic control circuit according to any one of the preceding claims, characterized in that the feed pump is adapted to control the pressure and volume flow on the basis of a measured actual transmission ratio and the desired transmission ratio.
    [8]
    The hydraulic control circuit according to any one of the preceding claims, characterized in that after controlling a change of the transmission ratio, assuming a condition where the pulleys have an equal running radius, the hydraulic control circuit is arranged to supply hydraulic fluid with the first pressure to be delivered to the pulley actuator that is predicted to have the lowest running radius after that change.
    BE2018 / 5610
    [9]
    The hydraulic control circuit according to any one of the preceding claims, characterized in that the feed pump is driven by an electric motor;
    [10]
    The hydraulic control circuit according to any one of claims 1 to 8, characterized in that the feed pump is driven by a combustion engine;
    [11]
    The hydraulic control circuit according to any one of the preceding claims, characterized in that the feed pump is driven by an electric motor;
    [12]
    A continuously variable transmission comprising a primary pulley (21) with an input shaft and a second pulley (23) with an output shaft, as well as an endless flexible transmission element (25) that mechanically couples the pulleys, the first and the second pulley is axially controlled by a respective actuator controlled by a hydraulic control circuit according to any of the preceding claims.
    [13]
    A method of controlling a transmission ratio of a continuously variable transmission, comprising a primary pulley with an input shaft and a second pulley with an output shaft, as well as an endless, flexible transmission element that mechanically couples the pulleys, the method comprises: axially moving the pulleys to achieve a transmission ratio between the input shaft and the output shaft and a clamp level for the flexible transmission element, the method comprising driving the pulleys by actuation with a hydraulic fluid at a first, respectively and a second operating pressure value, comprising supplying hydraulic fluid at a base fluid pressure value, pumping hydraulic fluid to increase an axial displacement of a pulley controllably selected from both pulleys, while axially displacing the controllably non-selected pulley is comminuted, further comprising se selectively controlling hydraulic fluid supply with the base fluid pressure value for operating the pulley designated as the one with the smallest running radius in that operating condition.
    类似技术:
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    同族专利:
    公开号 | 公开日
    BE1026582B1|2020-03-31|
    CN112789432A|2021-05-11|
    BE1026582A1|2020-03-24|
    BE1026582B9|2020-06-08|
    WO2020043894A1|2020-03-05|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    DE3934506C1|1989-10-16|1991-05-08|Ford-Werke Ag, 5000 Koeln, De|
    NL1009954C1|1998-08-27|2000-02-29|Gear Chain Ind Bv|Control system for a continuously variable transmission with two cone-disk pairs of conical pulley adjustable by means of an endless transmission medium.|
    US6287227B1|1999-09-20|2001-09-11|General Motors Corporation|Hydraulic control for a continuously variable transmission|
    WO2013097880A1|2011-12-29|2013-07-04|Robert Bosch Gmbh|Hydraulically actuated continuously variable transmission for a vehicular drive line provided with an engine|
    JP6182293B2|2014-06-23|2017-08-16|本田技研工業株式会社|Hydraulic control device|
    CN106838301B|2017-01-19|2018-07-06|湘潭大学|A kind of contiuously variable transmission metal tape clamping force control device and control method|
    法律状态:
    2020-05-04| FG| Patent granted|Effective date: 20200331 |
    2021-05-26| MM| Lapsed because of non-payment of the annual fee|Effective date: 20200831 |
    2021-05-26| RC| Pledge established (pawning)|Free format text: DETAILS PLEDGE: RIGHT OF PLEDGE, ESTABLISHED Name of requester: BNP PARIBAS FORTIS NV/SA Effective date: 20201021 |
    优先权:
    申请号 | 申请日 | 专利标题
    BE20185610A|BE1026582B9|2018-08-31|2018-08-31|A hydraulic control circuit for a continuously variable transmission, a continuously variable transmission and a method for controlling the clamping forces of a continuously variable transmission.|BE20185610A| BE1026582B9|2018-08-31|2018-08-31|A hydraulic control circuit for a continuously variable transmission, a continuously variable transmission and a method for controlling the clamping forces of a continuously variable transmission.|
    CN201980064222.0A| CN112789432A|2018-08-31|2019-08-30|Hydraulic control circuit for continuously variable transmission, and method for controlling clamping force of continuously variable transmission|
    PCT/EP2019/073248| WO2020043894A1|2018-08-31|2019-08-30|A hydraulic control circuit for a continuously variable transmission, a continuously variable transmission and a method for controlling the clamping forces of a continuously variable transmission.|
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