Abstract: A hydraulic controller (10, 10a, 10b) comprising a power part that is supplied by a high-pressure pump (42), and a control part and connecting lines is proposed. According to the invention, a low-pressure pump (64) is provided for the control part. This has an advantageous effect on leakage and fuel consumption.

Abstract: The present invention relates to a method for detecting a slip (s) of a belt part of a belt transmission, especially of a CVT transmission, having a transmission rpm ratio (ji).

Abstract: A system hydraulically adjusts the transmission ratio of a continuously variable transmission in a motor vehicle. The adjustment of the transmission ratio takes place by the drive of at least one valve via an electrical signal. Furthermore, in one operating state of the transmission, the transmission ratio is held essentially constant in that the electrical signal is set to a pregivable value. The valve then assumes the above-mentioned center position (blocking position). This operating state is also characterized as the ratio-hold state. The pregivable value can be changed in the normal operation of the vehicle. Component tolerances are compensated during operation of the vehicle or the transmission.

Abstract: The invention relates to an arrangement and a method for determining the transmission ratio of a continuously variable transmission having a drive end and an output end. A signal, which represents the transmission ratio, is computed in dependence upon a primary rpm of the drive end and a secondary rpm of the output end which are transmitted to the arrangement. A fault signal is generated which is dependent upon the instantaneous primary rpm and/or the instantaneous secondary rpm and indicates whether a value for the transmission ratio is to be outputted as the signal representing the transmission ratio. This value is computed from the detected instantaneous values for the primary rpm and the secondary rpm.

Abstract: A system (10), in particular an electrohydraulic system (10), for adjusting the contract pressures of a continuously variable gear, in particular a double-cone pulley belt-contact gear, which has a device for changing the gear ratio of the gear having at least one primary pressure chamber and one secondary pressure chamber is proposed. An electrically triggerable primary pressure valve (Vprim) for adjusting the pressure in the primary pressure chamber and an electrically triggerable secondary pressure valve (Vsec) for adjusting the pressure in the secondary pressure chamber are provided. The pressure (pprim) of the primary pressure chamber and the pressure (psec) of the secondary pressure chamber can be carried to the secondary pressure valve (Vsec). The object is to enable a more-accurate adjustment of the pressure (pprim) in the primary pressure chamber.

Abstract: In an emergency hydraulic control, in which in an open hydraulic circuit for supplying the various piston chambers of the secondary and primary axial adjusters, at least one throttle valve is disposed. For regulating the primary and secondary pressure, a primary and secondary valve are used, respectively. Each valve is triggered in turn via a respective electromagnetically actuated pilot control valve in the pilot control valve that opens in emergency operation; the pilot control valves are connected to the outlet of the secondary valve, among others, via orifice valves. The pressure fluid pressure in the primary piston chamber is additionally limited by a pressure limiting valve. The outlet of this pressure limiting valve is connected via a control line to the control line located between the primary pilot control valve and the primary valve.

Abstract: The invention proceeds from a system for adjusting the tension of a belt part (for example, a band) of a belt transmission mounted downstream of a vehicle engine. The belt transmission preferably is continuously adjustable with respect to its transmission ratio. A first means is provided for controlling (open loop and/or closed loop) the vehicle engine and a second means is provided for controlling (open loop and/or closed loop) the belt transmission. Here, a first signal is determined by the first means and this signal represents the engine torque of the vehicle engine and this signal is supplied by the first means to the second means. The tension is adjusted by the second means in dependence upon the first signal and a safety reserve. The essence of the invention is that the safety reserve is not fixedly pregiven; instead, it is determined in dependence upon various conditions.

Abstract: The invention proceeds from a system for generating a signal for hydraulically adjusting the transmission ratio of a continuously variable transmission in a motor vehicle. Here, a valve is provided which influences the hydraulic connection from a pressure reservoir, which exhibits a hydraulic pressure, to a pressure chamber. The adjustment of the transmission ratio takes place via the drive of at least the valve via the electrical signal. For this purpose, the electrical signal is generated in such a manner that it is limited to maximum and/or minimum values. The essence of the invention is that the maximum and/or minimum values are determined in dependence upon the hydraulic pressure. With the limiting in accordance with the invention, it is ensured that an adequate pressure reserve for the adjustment of the belt tension is available notwithstanding the adjustment of the transmission ratio.

Abstract: The invention is directed to a method and an arrangement for controlling a drive train of a motor vehicle which includes at least: a motor, a transmission and a main clutch. The transmission is especially a transmission continuously variable with respect to its transmission ratio. Furthermore, at least two driving states of the drive train are provided which can be selected by the driver of the vehicle. The first driving state is provided in normal driving operation; whereas, in the second driving state, the force flow in the drive train is essentially interrupted. The essence of the invention is that the motor rpm is adjusted to the transmission input rpm in the second operating state wherein the force flow is essentially interrupted in the drive train. The vehicle speed can be considered as an additional criterion for adjusting the motor rpm.

Abstract: The invention proceeds from a control of a transmission, which is continuously adjustable with respect to its transmission ratio, for a motor vehicle wherein the transmission together with a drive unit is mounted in the drive train of the motor vehicle. The drive unit has an adjustable output torque. According to the invention, determination means for determining a quantity is provided which represents the instantaneous maximum transmittable torque of the transmission. Furthermore, the output torque of the drive unit is limited to a limit value by limiting means. This limit value is determined in dependence upon the above-determined quantity. In order to reliably protect the transmission against damage by increased slippage, it is therefore provided according to the invention to limit the torque outputted by the engine when the contact force is so small that the danger of slippage exists. The torque of the motor can, in general, be more rapidly limited than the contact force can be increased.

Abstract: The invention proceeds from an arrangement or a method for adjusting the transmission ratio of a continuously variable belt transmission having a drive end and an output end. The drive end and the output end have at least one axially displaceable element which has essentially the form of a conical disc. Via sensor means, an rpm signal is detected, which represents the rotational movement of the drive end or the output end, and, on the other hand, a displacement signal is detected which represents the axial displacement of at least one of the axially displaceable elements. The essence of the invention is that means for adjusting the transmission ratio are provided with the aid of which the adjustment takes place at least in dependence upon the detected displacement signal. An advantage of the invention is that, in this way, the possibility is provided to save one rpm sensor.

Abstract: The invention relates to an adjustment of the transmission ratio of a transmission having a primary end and a secondary end. The transmission is continuously variably adjusted with respect to its transmission ratio and is mounted between a vehicle engine and the drive wheels. According to the invention, means are provided by means of which a deceleration state of the vehicle of a pregivable or pregiven extent is determined. The output rpm of the vehicle engine is adjusted or controlled in dependence upon the detected rpm of the primary end in response to the determination of one such deceleration state. With the invention, it can be ensured that the vehicle with a CVT transmission comes to standstill for a transmission ratio close to the start transmission ratio even for especially intense decelerations at low speeds (30 to 60 km/hour).

Abstract: A system for adjusting the tension of a belt of a belt transmission provides a higher accuracy of the estimate of the engine torque, which is to be expected, and therefore a better proportioning of the tension is obtained. For this purpose, signals are made available from the engine control which controls the internal combustion engine. These signals make possible a precise estimation of the engine torque. In a first embodiment, this signal can, for example, be an estimated value for the engine torque to be expected. The estimated value is, for example, formed in the engine control. In a second embodiment, these signals can be the quantity of air mass inducted by the engine (that is, the signal derived therefrom) and the ignition angle of the engine. The tension of the belt can be reduced by the more accurate estimate of the engine torque so that an improved transmission efficiency results.

Abstract: A hydraulic emergency control for changing the hydraulic oil pressure in the hydraulic conical pulley axial adjustment mechanism of a continuously variable transmission (10) for varying the clamping force ratio has a pump (20) in an open hydraulic circuit that supplies the respective piston chambers (17, 13) of the secondary and primary axial adjustment mechanisms with hydraulic oil. The primary and secondary oil pressures are regulated by separate oil pressure limiting valves (30, 40). At least one throttle valve (51) is arranged between the pump (20) and the output pipe (92) of the open hydraulic circuit, at a point where the pump volumetric flow can be influenced. The hydraulic emergency control allows a starting transmission ratio to be set in a low range when starting the vehicle, whereas a very small reduction ratio is selected at a high driving speed and at light throttle.

Abstract: A hydraulic emergency control for a gear-ratio-dependent change in hydraulic fluid pressures in a first and second hydraulic bevel-gear axial adjuster of a continuously variable transmission (10), is provided in which a pump (1) supplies at least the piston chamber (17) of the second axial adjuster, and at least one downstream pressure limiting valve (40) limits the fluid pressure there and moreover from this supply, via a continuous path valve (20), supplies the piston chamber (13) of the first axial adjuster, and the continuous path valve (20) is controlled with the aid of a pressure differential acting on a throttle valve (39) that is downstream of the pump (1) and is integrated with a switching valve (30).

Abstract: A hydraulic emergency control system for a continuous looped gear type continuously variable transmission (10) includes first and second hydraulic beveled conical pulley axial actuators controlling a gear ratio. A pump supplies a first piston chamber (13) of said first axial actuator via a sensor valve (20), wherein the sensor valve (20) is controlled by a flow control valve (73) connected downstream of the pump (80). The pump (80) supplies a second piston chamber (17) of the second axial actuator, with a pressure relief valve (40) limiting fluid pressure in said second piston chamber. Fluid in the second piston chamber (17) is controlled as a function of the fluid pressure in the first piston chamber (13) via a control line (52, 113).

Abstract: The electro-hydraulic control device is designed to control a continuously variable loop transmission including a hydraulic bevel disk displacement device having two pairs of bevel disks, each pair of which has piston/cylinder elements with a piston chamber, and a pump for supplying one of the piston chambers with hydraulic oil. The electro-hydraulic control device supplies and regulates a hydraulic pressure in the piston chamber by means of a flow control valve (50) and a proportioning pressure relief valve (30). The electro-hydraulic control device also includes a pressure sensor (90) for generating an electronic pressure sensor signal according to the hydraulic pressure in a low-pressure control pressure line (34) connecting the flow control valve (50) and the proportioning pressure relief valve (30) and an electronic control unit for generating an electrical current for actuating the flow control valve (50) according to the pressure sensor signal.

Abstract: For an electro-hydraulically actuable continuously variable belt transmission, the selected contact pressure at the movable conical pulley discs must be of such a magnitude that the chain, the force transmitting belt or the like does not slip. On the other hand, the contact pressure should not be too great for a high efficiency of the transmission to be achieved at every operating point. The invention reliably prevents slippage of the belt (chain, force transmitting belt or the like) by controlling the belt slip. The mean contact pressure is thereby reduced. As a result, there is a decrease in the mechanical and hydraulic losses at the transmission. A variant of the invention includes an embodiment of a rotational-speed sensor which makes it simultaneously possible to measure the axial position of the pulley disc(s). As a result, there is a reduction in the additional complexity required for slip control compared to the belt-tension control.

Abstract: A method for operating a motor vehicle such as a passenger car, which is equipped with a motor and an electronically controlled, continuously variable transmission includes the steps of: detecting a driving state defined by downhill travel; detecting the speed of the vehicle at the start of the downhill travel and storing the vehicle speed; continuously changing the transmission in such a manner that the vehicle speed is substantially maintained while utilizing the braking action of the motor thereby defining a downhill travel motor braking mode of operation; and/or, detecting possible slip at the wheels of the motor vehicle and adjusting a corresponding other, lower gear ratio continuously on the transmission so that the slip is reduced or is entirely eliminated thereby defining a slip-adjustment mode of operation; and/or, detecting if a braking operation is present and, during braking operation, continuously adjusting the transmission by changing the gear ratio to support the brakes of the motor vehicle to