CA2935364C - Hydrostatic transmission, drive train having the transmission and method for controlling the transmission - Google Patents
Hydrostatic transmission, drive train having the transmission and method for controlling the transmission Download PDFInfo
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- CA2935364C CA2935364C CA2935364A CA2935364A CA2935364C CA 2935364 C CA2935364 C CA 2935364C CA 2935364 A CA2935364 A CA 2935364A CA 2935364 A CA2935364 A CA 2935364A CA 2935364 C CA2935364 C CA 2935364C
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- hydraulic machine
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/42—Control of exclusively fluid gearing hydrostatic involving adjustment of a pump or motor with adjustable output or capacity
- F16H61/431—Pump capacity control by electro-hydraulic control means, e.g. using solenoid valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/4008—Control of circuit pressure
- F16H61/4017—Control of high pressure, e.g. avoiding excess pressure by a relief valve
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/42—Control of exclusively fluid gearing hydrostatic involving adjustment of a pump or motor with adjustable output or capacity
- F16H61/433—Pump capacity control by fluid pressure control means
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
- F16H59/68—Inputs being a function of gearing status
- F16H2059/6838—Sensing gearing status of hydrostatic transmissions
- F16H2059/6861—Sensing gearing status of hydrostatic transmissions the pressures, e.g. high, low or differential pressures
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H2312/00—Driving activities
- F16H2312/20—Start-up or shut-down
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
- F16H59/60—Inputs being a function of ambient conditions
- F16H59/64—Atmospheric temperature
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Control Of Fluid Gearings (AREA)
Abstract
A hydrostatic transmission for a drive train is disclosed, said transmission comprising a first hydraulic machine that can be coupled to a drive machine and comprises an adjustable first displacement volume and is arranged together with at least one second hydraulic machine of the transmission in a hydraulic circuit and said second hydraulic machine can be coupled to an output of the drive train, wherein a control pressure of the transmission at the first hydraulic machine is effective in the direction in which the first displacement volume is increased and a working pressure of the second hydraulic machine that is dependent upon this adjustment is effective in the opposite direction, so that the working pressure can be controlled by way of the control device of the transmission by means of changing the control pressure. A hydrostatic drive train having this transmission is disclosed and a method for controlling the transmission of said drive train is disclosed.
Description
Hydrostatic transmission, drive train having the transmission and method for controlling the transmission Description The invention relates to a hydrostatic transmission, a drive train having said transmission, and also a method for controlling the working pressure of said transmission.
Hydrostatic transmissions that comprise a first hydraulic machine that can be driven by a drive machine and is fluid connected in an in particular closed hydraulic circuit to a second hydraulic machine require a warm-up phase at a limited working pressure so as to avoid damaging the transmission in the case by way of example of the pressure medium temperature being too low. Such warm-up phases are by way of example specified in the data sheets of the hydraulic machines. One example for a warm-up phase of a conventional axial piston machine in the temperature range of -40 C to -20 C proposes a specification by way of example that during the warm-up phase the working pressure p must be less than or equal to a predetermined fraction of the nominal pressure pnon, within a time period t less than or equal to 15 minutes.
Furthermore, a rotational speed n may not exceed a predetermined fraction of the nominal rotational speed nnom.
However, in the case of hydraulic machines that do not have a pressure controlling arrangement, the permitted limit for the working pressure can be exceeded during the warm-up phase even in the case of a low rotational speed and small displacement volume if the hydraulic machine is used as a pump.
Hydrostatic transmissions that comprise a first hydraulic machine that can be driven by a drive machine and is fluid connected in an in particular closed hydraulic circuit to a second hydraulic machine require a warm-up phase at a limited working pressure so as to avoid damaging the transmission in the case by way of example of the pressure medium temperature being too low. Such warm-up phases are by way of example specified in the data sheets of the hydraulic machines. One example for a warm-up phase of a conventional axial piston machine in the temperature range of -40 C to -20 C proposes a specification by way of example that during the warm-up phase the working pressure p must be less than or equal to a predetermined fraction of the nominal pressure pnon, within a time period t less than or equal to 15 minutes.
Furthermore, a rotational speed n may not exceed a predetermined fraction of the nominal rotational speed nnom.
However, in the case of hydraulic machines that do not have a pressure controlling arrangement, the permitted limit for the working pressure can be exceeded during the warm-up phase even in the case of a low rotational speed and small displacement volume if the hydraulic machine is used as a pump.
- 2 -The unexamined German application DE 10 2011 120 665 Al discloses a hydrostatic transmission having a hydraulic pump and a hydraulic motor. Said application explains how the working pressure is determined on the basis of a torque balance and an ascertained or estimated displacement volume of the hydraulic pump. In order to perform this procedure it is necessary to know the magnitude of the torque of the drive machine, to be aware of all auxiliary consumers and to know the drive torque MF. Although it is possible to determine the working pressure by means of the proposed torque balance and the displacement volume of the hydraulic pump, a considerable expenditure with regard to the sensor system is however still necessary for ascertaining the torque and the displacement volume. In addition, owing to the proposed estimates for the torque values and the displacement volume of the hydraulic pump, the method is encumbered by a degree of uncertainty with regard to the result of the working pressure. Consequently, any limitation of the working pressure on the basis of this method is associated with a degree of uncertainty and a risk of the hydrostatic transmission being overloaded.
The printed publication US 5,410878 proposes a comprehensive sensor system for ensuring that a warm-up phase is maintained. Said publication thus proposes the rotational speed of the drive machine, the magnitude of leakage oil, the working pressure of the hydraulic pump, a temperature sensor for ascertaining the oil temperature of the drive machine, and said publication proposes a temperature sensor for ascertaining the temperature of the cooling medium of the drive machine and also proposes a temperature sensor for ascertaining the temperature of the pressure medium of the
The printed publication US 5,410878 proposes a comprehensive sensor system for ensuring that a warm-up phase is maintained. Said publication thus proposes the rotational speed of the drive machine, the magnitude of leakage oil, the working pressure of the hydraulic pump, a temperature sensor for ascertaining the oil temperature of the drive machine, and said publication proposes a temperature sensor for ascertaining the temperature of the cooling medium of the drive machine and also proposes a temperature sensor for ascertaining the temperature of the pressure medium of the
- 3 -hydraulic circuit. A control system that processes input signals continuously compares the rotational speed of the drive machine, the leakage current and the working pressure until the said temperatures adhere to the necessary, predetermined limit values. A disadvantage of this system is the costly sensor system and the requirement to process the measuring signals in order to be able to sufficiently ensure the warm-up phase.
The printed publication EP 2 767 739 Al describes an approach that uses less sensor technology and indicates a power split transmission having a hydrostatic power branch.
The hydraulic pump is embodied in such a manner that a control pressure that acts on said hydraulic pump is effective in the direction in which the displacement volume of said pump is increased and the working pressure that is subsequently set in the hydraulic circuit is effective in the direction in which the displacement volume of said pump is reduced. By way of controlling the control pressure, by way of example by way of a pressure reducing valve such as is disclosed in the printed publication DE 10 2005 037 619 Al, a controlling influence can then be exerted on the working pressure. Hydraulic machines that are constructed in this manner (hydraulic pumps) are by way of example known from the data sheet RD92004/06.12 issued by the applicant. A
disadvantage of this solution is that the loading on the hydraulic circuit during the warm-up phase cannot be avoided.
It is desirable to provide a hydrostatic transmission having an improved protection against being damaged. Furthermore, a drive transmission having this hydrostatic transmission and
The printed publication EP 2 767 739 Al describes an approach that uses less sensor technology and indicates a power split transmission having a hydrostatic power branch.
The hydraulic pump is embodied in such a manner that a control pressure that acts on said hydraulic pump is effective in the direction in which the displacement volume of said pump is increased and the working pressure that is subsequently set in the hydraulic circuit is effective in the direction in which the displacement volume of said pump is reduced. By way of controlling the control pressure, by way of example by way of a pressure reducing valve such as is disclosed in the printed publication DE 10 2005 037 619 Al, a controlling influence can then be exerted on the working pressure. Hydraulic machines that are constructed in this manner (hydraulic pumps) are by way of example known from the data sheet RD92004/06.12 issued by the applicant. A
disadvantage of this solution is that the loading on the hydraulic circuit during the warm-up phase cannot be avoided.
It is desirable to provide a hydrostatic transmission having an improved protection against being damaged. Furthermore, a drive transmission having this hydrostatic transmission and
- 4 -a method for controlling the hydrostatic transmission are also desirable.
In one aspect, the invention provides a hydrostatic transmission for a drive train (1; 101), said transmission comprising a first hydraulic machine (8; 108) that can be coupled to a drive machine (2) and comprises an adjustable first displacement volume (VHp) and is arranged together with at least one second hydraulic machine (14) of the transmission (4, 104) in a hydraulic circuit and said second hydraulic machine can be coupled to an output of the drive train (1; 101), wherein a control pressure (pst) of the transmission (4, 104) at the first hydraulic machine (8;
108), is effective in the direction in which the first displacement volume (Viip) is increased and a working pressure (p) of the second hydraulic machine (14) that is dependent upon this adjustment is effective in the opposite direction, so that the working pressure (p) can be controlled by way of a control device (20) of the transmission (4; 104) by means of changing the control pressure (Pst), characterized in that an operating phase of the transmission (4; 104) is parameterized in the control device (20) during which by way of the control device (20) the working pressure (p) and/or a first rotational speed (flip) of the first hydraulic machine (8; 108) is or are limited to a fraction of an allocated nominal value (Pnorn, nnorn).
In one aspect, the invention provides a hydrostatic drive train comprising the hydrostatic transmission described herein.
In one aspect, the invention provides a method for controlling the hydrostatic transmission described herein,
In one aspect, the invention provides a hydrostatic transmission for a drive train (1; 101), said transmission comprising a first hydraulic machine (8; 108) that can be coupled to a drive machine (2) and comprises an adjustable first displacement volume (VHp) and is arranged together with at least one second hydraulic machine (14) of the transmission (4, 104) in a hydraulic circuit and said second hydraulic machine can be coupled to an output of the drive train (1; 101), wherein a control pressure (pst) of the transmission (4, 104) at the first hydraulic machine (8;
108), is effective in the direction in which the first displacement volume (Viip) is increased and a working pressure (p) of the second hydraulic machine (14) that is dependent upon this adjustment is effective in the opposite direction, so that the working pressure (p) can be controlled by way of a control device (20) of the transmission (4; 104) by means of changing the control pressure (Pst), characterized in that an operating phase of the transmission (4; 104) is parameterized in the control device (20) during which by way of the control device (20) the working pressure (p) and/or a first rotational speed (flip) of the first hydraulic machine (8; 108) is or are limited to a fraction of an allocated nominal value (Pnorn, nnorn).
In one aspect, the invention provides a hydrostatic drive train comprising the hydrostatic transmission described herein.
In one aspect, the invention provides a method for controlling the hydrostatic transmission described herein,
- 5 -characterized by the step of limiting the working pressure (P) and/or limiting the first rotational speed (nlip) to the fraction of the allocated nominal value (Pnomf nnom) during the operating phase by way of the control device (20).
A hydrostatic transmission for a drive train comprises a first hydraulic machine that can be coupled to a drive machine and comprises an adjustable first displacement volume and is arranged together with at least one second hydraulic machine of the transmission in an in particular closed hydraulic circuit, said hydraulic machine can be coupled to an output of the drive train. A control pressure of the transmission is effective at the first hydraulic machine, in particular at an adjusting element, so as to adjust the first displacement volume in a direction in which the first displacement volume is increased, and a working pressure of the second hydraulic machine that is dependent upon this adjustment is effective in the opposite direction.
In this manner, the working pressure of the transmission can be controlled by way of the control device by means of changing, in particular adjusting, the control pressure. In accordance with the invention, an operating phase of the transmission is parameterized in the control device during which by way of the control device the working pressure or a first rotational speed of the first hydraulic machine, or both, is or are limited to a fraction of its respective allocated nominal value.
In this manner, the hydrostatic transmission is better protected in the operating phase against damage owing to an excessively high working pressure and/or an excessively high first rotational speed. The design of the first hydraulic machine and the associated ability of the working pressure
A hydrostatic transmission for a drive train comprises a first hydraulic machine that can be coupled to a drive machine and comprises an adjustable first displacement volume and is arranged together with at least one second hydraulic machine of the transmission in an in particular closed hydraulic circuit, said hydraulic machine can be coupled to an output of the drive train. A control pressure of the transmission is effective at the first hydraulic machine, in particular at an adjusting element, so as to adjust the first displacement volume in a direction in which the first displacement volume is increased, and a working pressure of the second hydraulic machine that is dependent upon this adjustment is effective in the opposite direction.
In this manner, the working pressure of the transmission can be controlled by way of the control device by means of changing, in particular adjusting, the control pressure. In accordance with the invention, an operating phase of the transmission is parameterized in the control device during which by way of the control device the working pressure or a first rotational speed of the first hydraulic machine, or both, is or are limited to a fraction of its respective allocated nominal value.
In this manner, the hydrostatic transmission is better protected in the operating phase against damage owing to an excessively high working pressure and/or an excessively high first rotational speed. The design of the first hydraulic machine and the associated ability of the working pressure
- 6 -to be controlled by way of controlling the control pressure has proved itself to be particularly simple as far as the technology regarding the device is concerned since it is possible on the basis of knowing the dependency of the working pressure upon the control pressure to omit a costly pressure sensor system. The hydrostatic transmission is consequently protected in the operating phase against the said overload without the use of a costly pressure sensor system.
In a further development, the hydraulic circuit comprises at least one further second hydraulic machine that can be supplied with a pressure medium by way of the first hydraulic machine. It is preferred that the second hydraulic machines can be connected in a hydraulic parallel manner to the first hydraulic machine, in particular brought into connection therewith, in such a manner that pressure medium can be supplied by way of said parallel connection.
It is preferred that the one or the multiple second hydraulic machines likewise comprise in each case a second displacement volume that can be adjusted by the control device. The one or the multiple second hydraulic machines have preferably an adjusting device by way of which the respective second displacement volume can be adjusted proportionally with respect to an electrical desired value signal. The actual value of the second displacement volume that has been controlled in this manner is essentially known in an advantageous manner when the desired value signal for the second displacement volume is known.
In a further development, the fraction amounts to between 60% and 80%, in particular approx. 70% of the respective
In a further development, the hydraulic circuit comprises at least one further second hydraulic machine that can be supplied with a pressure medium by way of the first hydraulic machine. It is preferred that the second hydraulic machines can be connected in a hydraulic parallel manner to the first hydraulic machine, in particular brought into connection therewith, in such a manner that pressure medium can be supplied by way of said parallel connection.
It is preferred that the one or the multiple second hydraulic machines likewise comprise in each case a second displacement volume that can be adjusted by the control device. The one or the multiple second hydraulic machines have preferably an adjusting device by way of which the respective second displacement volume can be adjusted proportionally with respect to an electrical desired value signal. The actual value of the second displacement volume that has been controlled in this manner is essentially known in an advantageous manner when the desired value signal for the second displacement volume is known.
In a further development, the fraction amounts to between 60% and 80%, in particular approx. 70% of the respective
- 7 -nominal value. The respective nominal value is a specific characteristic of the respective hydraulic machine and/or of the hydrostatic transmission and is preferably stored in the control device.
In one possible embodiment, the first hydraulic machine is embodied as an adjustable axial piston machine of a swash plate design and comprises working pistons that rotate with a drive shaft, said working pistons being supported on a swash plate that can pivot about a pivot axis. The swash plate is the already mentioned adjusting element. It is preferred that the drive shaft can be coupled to the drive machine. It is preferred that the swash plate is articulated to the pivot axis at a distance from an adjusting device in particular an actuating cylinder that can be influenced by the control pressure medium. The control pressure is the pressure of the control pressure medium. Hydrostatic working chambers that can be delimited by the working pistons and are part of the first hydraulic machine can be connected in an alternating manner to the low pressure and high pressure side of said first hydraulic machine in a fluid medium-connected manner by way of a swash plate that is penetrated by two pressure nodules. The swash plate is preferably arranged so as to rotate about its longitudinal axis so that at least one of the pressure nodules is arranged distributed in an asymmetrical manner in relation to one of the pivot axis and the axis of rotation of the working chambers or from its plane that extends in a parallel manner. In this manner, the working pressure is effective as already mentioned in the direction in which the first displacement volume is reduced.
In one possible embodiment, the first hydraulic machine is embodied as an adjustable axial piston machine of a swash plate design and comprises working pistons that rotate with a drive shaft, said working pistons being supported on a swash plate that can pivot about a pivot axis. The swash plate is the already mentioned adjusting element. It is preferred that the drive shaft can be coupled to the drive machine. It is preferred that the swash plate is articulated to the pivot axis at a distance from an adjusting device in particular an actuating cylinder that can be influenced by the control pressure medium. The control pressure is the pressure of the control pressure medium. Hydrostatic working chambers that can be delimited by the working pistons and are part of the first hydraulic machine can be connected in an alternating manner to the low pressure and high pressure side of said first hydraulic machine in a fluid medium-connected manner by way of a swash plate that is penetrated by two pressure nodules. The swash plate is preferably arranged so as to rotate about its longitudinal axis so that at least one of the pressure nodules is arranged distributed in an asymmetrical manner in relation to one of the pivot axis and the axis of rotation of the working chambers or from its plane that extends in a parallel manner. In this manner, the working pressure is effective as already mentioned in the direction in which the first displacement volume is reduced.
- 8 -In a further development, the operating phrase is an inflow phase, in particular a warm-up or warming phase, or said operating phase is an outflow phase, in particular a cooling down phase, of the transmission or at least of its hydraulic machines. Both the inflow phase and also the outflow phase are characterized in that they have the goal of bringing relevant process variables of the transmission or at least of one of the hydraulic machines into an allocated designated range.
In a further development, both the inflow phase and also the outflow phase are stored in a parameterized manner in the control device. It is possible in this manner to start up the hydrostatic transmission but also to shut down the hydrostatic transmission, by way of example following an overload, in a controlled and reliable manner as a result of the pressure limitation and/or the first rotational speed limitation.
In a further development, a termination criterion is stored in the control device and the operating phase can be terminated, in particular is terminated, by way of the control device on the basis of said criterion being fulfilled. The termination criterion can be by way of example a fixedly parameterized duration of the operation phase. By way of example a duration of 5 to 30 minutes, in particular 15 minutes can be provided for a hydrostatic transmission.
In a further development, a start-up criterion is stored in the control device and the operating phase can be started up by way of the control device on the basis of said criterion being fulfilled. By way of example, the start-up criterion
In a further development, both the inflow phase and also the outflow phase are stored in a parameterized manner in the control device. It is possible in this manner to start up the hydrostatic transmission but also to shut down the hydrostatic transmission, by way of example following an overload, in a controlled and reliable manner as a result of the pressure limitation and/or the first rotational speed limitation.
In a further development, a termination criterion is stored in the control device and the operating phase can be terminated, in particular is terminated, by way of the control device on the basis of said criterion being fulfilled. The termination criterion can be by way of example a fixedly parameterized duration of the operation phase. By way of example a duration of 5 to 30 minutes, in particular 15 minutes can be provided for a hydrostatic transmission.
In a further development, a start-up criterion is stored in the control device and the operating phase can be started up by way of the control device on the basis of said criterion being fulfilled. By way of example, the start-up criterion
- 9 -can be a start-up procedure of the transmission or drive train requested in particular by a user.
In addition or as an alternative to the already mentioned purely temporal definition of the start-up criterion and the termination criterion, it is possible to define both the termination criterion but also the start-up criterion in dependence upon at least one process variable of the transmission or at least of one of the hydraulic machines.
In this manner, the operating phase is started up or terminated not merely as a result of events (start-up, duration of the operation phase) that have a fixed duration but rather the operating phase is started up or terminated at the actual state of the transmission in dependence upon the process variables that are describing this state. It is possible in this manner to shorten or even omit the operating phase by way of example in the case of an early fulfillment of the necessary termination criterion so that operating time periods with reduced power are shortened.
However, extended operating time periods are also feasible in the case of the fulfillment of the termination criterion being delayed.
In principle, the start-up criterion is fulfilled if the process variable lies outside a designated range that is parameterized in the control device. Accordingly the termination criterion is fulfilled if the process variable lies within a designated range that is parameterized in the control device.
In a further development, the process variable is a pressure medium temperature of the hydraulic circuit of the transmission. As an alternative or in addition thereto, a
In addition or as an alternative to the already mentioned purely temporal definition of the start-up criterion and the termination criterion, it is possible to define both the termination criterion but also the start-up criterion in dependence upon at least one process variable of the transmission or at least of one of the hydraulic machines.
In this manner, the operating phase is started up or terminated not merely as a result of events (start-up, duration of the operation phase) that have a fixed duration but rather the operating phase is started up or terminated at the actual state of the transmission in dependence upon the process variables that are describing this state. It is possible in this manner to shorten or even omit the operating phase by way of example in the case of an early fulfillment of the necessary termination criterion so that operating time periods with reduced power are shortened.
However, extended operating time periods are also feasible in the case of the fulfillment of the termination criterion being delayed.
In principle, the start-up criterion is fulfilled if the process variable lies outside a designated range that is parameterized in the control device. Accordingly the termination criterion is fulfilled if the process variable lies within a designated range that is parameterized in the control device.
In a further development, the process variable is a pressure medium temperature of the hydraulic circuit of the transmission. As an alternative or in addition thereto, a
- 10 -process variable is also feasible that represents wear of the hydrostatic transmission or one of the components. The pressure medium temperature is particularly well suited for this since it is a direct indication of the viscosity and thus the lubricating capacity of the pressure medium and consequently for a protection against wear of the hydrostatic transmission.
In a further development, multiple sensing sites for sensing the pressure medium temperature are provided on the hydrostatic transmission. The start-up criterion and/or the termination criterion are defined by way of example by one of the ascertained pressure medium temperatures or in dependence upon at least two of the ascertained pressure medium temperatures or in dependence upon all ascertained pressure medium temperatures. It is possible depending upon each application and the importance of the sensing site to parameterize in the control device those pressure medium temperatures that are allocated to the respective criterion.
In a further development, a characteristic field of the control pressure in dependence upon the working pressure is stored in the control device for controlling the working pressure.
It is preferred that the characteristic field of the control pressure is stored also in dependence upon the first displacement volume.
In a further development, the characteristic field of the control pressure in dependence upon the first rotational speed or a first rotational speed range of this first rotational speed is also stored.
In a further development, multiple sensing sites for sensing the pressure medium temperature are provided on the hydrostatic transmission. The start-up criterion and/or the termination criterion are defined by way of example by one of the ascertained pressure medium temperatures or in dependence upon at least two of the ascertained pressure medium temperatures or in dependence upon all ascertained pressure medium temperatures. It is possible depending upon each application and the importance of the sensing site to parameterize in the control device those pressure medium temperatures that are allocated to the respective criterion.
In a further development, a characteristic field of the control pressure in dependence upon the working pressure is stored in the control device for controlling the working pressure.
It is preferred that the characteristic field of the control pressure is stored also in dependence upon the first displacement volume.
In a further development, the characteristic field of the control pressure in dependence upon the first rotational speed or a first rotational speed range of this first rotational speed is also stored.
- 11 -In a further development, the hydrostatic transmission comprises a pressure control device or a pressure reducing device, in particular a pressure control valve or a pressure reducing valve that can be controlled by way of the control device by means of an electrical desired value signal of the control pressure. The respective device is embodied in such a manner that the control pressure is controlled in a manner essentially proportional to the desired value signal.
Consequently, in the case of a known desired value signal the control pressure and, as a result of the previously discussed characteristic of the first hydraulic machine, the working pressure are known.
In a further development, the control pressure for a traction operation and/or a braking operation of the second hydraulic machine is stored in the characteristic field. It is preferred that the first displacement volume of the first hydraulic machine can be adjusted on both sides of a zero setting and the control pressure is stored on both sides of the zero setting in the characteristic field. It is preferred that a desired torque of the second hydraulic machine can be requested by a user. It is preferred for this purpose that a desired working pressure can be determined by way of the control device in dependence upon a desired torque of the second hydraulic machine and in dependence upon the displacement volume of the second hydraulic machine. In this manner, the hydrostatic transmission or the drive train renders it possible for the vehicle to travel in a comfortable torque-based manner such as is known by way of example from the passenger car sector.
Consequently, in the case of a known desired value signal the control pressure and, as a result of the previously discussed characteristic of the first hydraulic machine, the working pressure are known.
In a further development, the control pressure for a traction operation and/or a braking operation of the second hydraulic machine is stored in the characteristic field. It is preferred that the first displacement volume of the first hydraulic machine can be adjusted on both sides of a zero setting and the control pressure is stored on both sides of the zero setting in the characteristic field. It is preferred that a desired torque of the second hydraulic machine can be requested by a user. It is preferred for this purpose that a desired working pressure can be determined by way of the control device in dependence upon a desired torque of the second hydraulic machine and in dependence upon the displacement volume of the second hydraulic machine. In this manner, the hydrostatic transmission or the drive train renders it possible for the vehicle to travel in a comfortable torque-based manner such as is known by way of example from the passenger car sector.
- 12 -A hydrostatic drive train comprises a hydrostatic transmission that is embodied at least in accordance with one of the aspects of the preceding description. The already known advantages of the hydrostatic transmission are provided in an identical manner for the hydrostatic drive train, as a consequence of which the drive train is also better protected against wear and malfunction.
A method for controlling a hydrostatic transmission that is embodied at least in accordance with one of the preceding aspects of the description comprises in accordance with the invention a step of "limiting the working pressure and/or limiting the first rotational speed to the fraction of the allocated nominal value during the operating phase by way of the control device". The advantages of the transmission that is controlled in this manner have already been explained and apply in an identical manner to the method so that further explanations are not necessary.
In a further development, the method includes a step of "starting the operating phase by way of the control device as soon as a start-up criterion for this step has been fulfilled". Furthermore, the method in this further development includes a step "terminating the operating phase by way of the control device as soon as a termination criterion for this step has been fulfilled". Possible types of the one or multiple start-up criterion or termination criterion have already been explained in the preceding description.
Two exemplary embodiments of a drive train in accordance with the invention having a hydrostatic transmission in accordance with the invention are illustrated in the
A method for controlling a hydrostatic transmission that is embodied at least in accordance with one of the preceding aspects of the description comprises in accordance with the invention a step of "limiting the working pressure and/or limiting the first rotational speed to the fraction of the allocated nominal value during the operating phase by way of the control device". The advantages of the transmission that is controlled in this manner have already been explained and apply in an identical manner to the method so that further explanations are not necessary.
In a further development, the method includes a step of "starting the operating phase by way of the control device as soon as a start-up criterion for this step has been fulfilled". Furthermore, the method in this further development includes a step "terminating the operating phase by way of the control device as soon as a termination criterion for this step has been fulfilled". Possible types of the one or multiple start-up criterion or termination criterion have already been explained in the preceding description.
Two exemplary embodiments of a drive train in accordance with the invention having a hydrostatic transmission in accordance with the invention are illustrated in the
- 13 -drawings. The invention is now further explained with reference to the figures in these drawings, in which:
Fig. 1 illustrates a first exemplary embodiment of a drive train in accordance with the invention with a hydrostatic transmission;
Fig. 2 illustrates a second exemplary embodiment of a drive train in accordance with the invention with a hydrostatic transmission; and Fig. 3 illustrates a characteristic field of a desired control pressure Pstson in dependence upon a working pressure p of the transmission arrangement and a first displacement volume VHp of the first hydraulic machine.
The common features of the two exemplary embodiments are first explained with reference to the Figures 1 and 2. In accordance with Figures 1 and 2, a drive train 1; 101, by way of example that of a mobile work machine, comprises a drive machine 2, which is embodied as a diesel motor, and a hydrostatic transmission 4; 104. The hydrostatic transmission 4; 104 comprises a first hydraulic machine 8;
108 that is embodied as an axial piston pump of a swash plate design and is connected by way of two working lines 10, 12 in a fluid manner in a closed, hydraulic circuit to a second hydraulic machine that is embodied as an axial piston motor of the bent axis design. The first hydraulic machine 8; 108 is coupled by way of a drive shaft 16 to the drive machine 2. A drive shaft 18 of the second hydraulic machine
Fig. 1 illustrates a first exemplary embodiment of a drive train in accordance with the invention with a hydrostatic transmission;
Fig. 2 illustrates a second exemplary embodiment of a drive train in accordance with the invention with a hydrostatic transmission; and Fig. 3 illustrates a characteristic field of a desired control pressure Pstson in dependence upon a working pressure p of the transmission arrangement and a first displacement volume VHp of the first hydraulic machine.
The common features of the two exemplary embodiments are first explained with reference to the Figures 1 and 2. In accordance with Figures 1 and 2, a drive train 1; 101, by way of example that of a mobile work machine, comprises a drive machine 2, which is embodied as a diesel motor, and a hydrostatic transmission 4; 104. The hydrostatic transmission 4; 104 comprises a first hydraulic machine 8;
108 that is embodied as an axial piston pump of a swash plate design and is connected by way of two working lines 10, 12 in a fluid manner in a closed, hydraulic circuit to a second hydraulic machine that is embodied as an axial piston motor of the bent axis design. The first hydraulic machine 8; 108 is coupled by way of a drive shaft 16 to the drive machine 2. A drive shaft 18 of the second hydraulic machine
14 is coupled to an output (not illustrated) of the drive train 1; 101. Both hydraulic machines 8; 108, 14 comprise in each case an adjustable displacement volume. They are embodied in such a manner that they can operate in all four quadrants, in both torque directions, both as a hydraulic pump and also as a hydraulic motor.
Furthermore, the hydrostatic transmission 4; 104 comprises a control device 20, in particular for controlling the torque MHM of the drive shaft 18. A first adjusting device 22; 122 of the first hydraulic machine 8; 108 is coupled in a signal-communicating manner to the control device 20 so as to adjust the first displacement volume VHp of said first hydraulic machine, and a second adjusting device 24 of the second hydraulic machine 14 is coupled in a signal-communicating manner to the control device 20 so as to adjust the second displacement volume VHm of said second hydraulic machine.
The hydrostatic transmission 4; 104 comprises a rotational speed sensor 26 by way of which the first rotational speed nHp of the first hydraulic machine 8; 108 can be ascertained.
The rotational speed sensor 26 is coupled in a signal-communicating manner to the control device 20 by way of the signal line 28. Alternatively, it is possible that the rotational speed niip is read in by way of a CAN bus from the rotational speed of the drive machine 2. In addition, the transmission 4; 104 comprises a temperature sensor 30 for ascertaining a pressure medium temperature of a leakage flow of the first hydraulic machine 8; 108. The latter is coupled in a signal-communicating manner to the control device 20 by way of a signal line 32.
In principle, a multi-stage gearbox is connected downstream of the hydrostatic transmission 4; 104 in order to cover a
Furthermore, the hydrostatic transmission 4; 104 comprises a control device 20, in particular for controlling the torque MHM of the drive shaft 18. A first adjusting device 22; 122 of the first hydraulic machine 8; 108 is coupled in a signal-communicating manner to the control device 20 so as to adjust the first displacement volume VHp of said first hydraulic machine, and a second adjusting device 24 of the second hydraulic machine 14 is coupled in a signal-communicating manner to the control device 20 so as to adjust the second displacement volume VHm of said second hydraulic machine.
The hydrostatic transmission 4; 104 comprises a rotational speed sensor 26 by way of which the first rotational speed nHp of the first hydraulic machine 8; 108 can be ascertained.
The rotational speed sensor 26 is coupled in a signal-communicating manner to the control device 20 by way of the signal line 28. Alternatively, it is possible that the rotational speed niip is read in by way of a CAN bus from the rotational speed of the drive machine 2. In addition, the transmission 4; 104 comprises a temperature sensor 30 for ascertaining a pressure medium temperature of a leakage flow of the first hydraulic machine 8; 108. The latter is coupled in a signal-communicating manner to the control device 20 by way of a signal line 32.
In principle, a multi-stage gearbox is connected downstream of the hydrostatic transmission 4; 104 in order to cover a
- 15 -greater rotational speed range of the drive shaft 18 and consequently to cover a greater speed range of the drive train 1; 101.
The two exemplary embodiments have in common that the second displacement volume VHm is adjusted in an electro-proportional manner by way of the adjusting device 24. The adjusting device 24 comprises for this purpose a hydraulic adjusting cylinder (not illustrated) whose mutually effective pressure chambers can be supplied in each case with a pressure medium by way of an electro-proportionally adjustable pressure control valve (not illustrated). The electro-proportional adjustment renders it possible to perform an infinitely variable adjustment to the displacement volume VHm. The adjustment is performed in a manner proportional to a desired value signal VHmson that is output by the control device 20 by way of the signal line 34. An advantage of this control concept for the second hydraulic machine 14 is the fact that the actual second displacement volume VHm corresponds essentially to the desired value VHMsoll of the second hydraulic machine 14 that is required by the control device 20.
The working pressure p in other words the higher of the two pressures in the working lines 10, 12 is controlled by way of the first hydraulic machine 8; 108. The control concept of the pressure control procedure on the basis of a control pressure Pst that is to be controlled is explained hereinunder. Two designs with technically different devices are possible and the alternatives are illustrated in the Figures 1 and 2.
The two exemplary embodiments have in common that the second displacement volume VHm is adjusted in an electro-proportional manner by way of the adjusting device 24. The adjusting device 24 comprises for this purpose a hydraulic adjusting cylinder (not illustrated) whose mutually effective pressure chambers can be supplied in each case with a pressure medium by way of an electro-proportionally adjustable pressure control valve (not illustrated). The electro-proportional adjustment renders it possible to perform an infinitely variable adjustment to the displacement volume VHm. The adjustment is performed in a manner proportional to a desired value signal VHmson that is output by the control device 20 by way of the signal line 34. An advantage of this control concept for the second hydraulic machine 14 is the fact that the actual second displacement volume VHm corresponds essentially to the desired value VHMsoll of the second hydraulic machine 14 that is required by the control device 20.
The working pressure p in other words the higher of the two pressures in the working lines 10, 12 is controlled by way of the first hydraulic machine 8; 108. The control concept of the pressure control procedure on the basis of a control pressure Pst that is to be controlled is explained hereinunder. Two designs with technically different devices are possible and the alternatives are illustrated in the Figures 1 and 2.
- 16 -The two different designs have the common feature that the working lines 10, 12 are protected by way of respective pressure limiting valves 36 that have an after suction function against being overloaded. Furthermore, the first hydraulic machine 8; 108 comprises a control pressure connection G at which a constant control pressure is available.
In accordance with Fig 1, the adjusting device 22 of the first hydraulic machine 8 comprises a pressure reducing valve 38. Said valve can be connected by way of a 4/3 directional control valve 40 having in each case a pressure medium chamber of an adjusting cylinder 42 whose piston 44 is coupled to an adjustable cradle of the first hydraulic machine 8 so as to adjust its first displacement volume VHP.
The pressure reducing valve 38 can be actuated in a directly controlled electromagnetic, electrical manner and is coupled by way of a signal line 46 in a signal-communicating manner to the control device 20. The control pressure that is supplied by the connection G is available at a control pressure inlet 50 of the pressure reducing valve 38 by way of a control pressure line 48. A valve body of the pressure reducing valve 38 is pre-stressed by way of a spring into an end position in which a control pressure outlet 52 of the pressure reducing valve 38 is connected in a pressure medium-conveying manner to a tank T. An electromagnet 54 that can be energized by way of the signal line 46 acts against the resilient force. In the case of said electromagnet being energized, the valve body of the pressure reducing valve 38 is displaced from the said end position (control pressure outlet 52 connected to the tank T) into intermediate positions in which the other end position that reveals the fluid connection of the control
In accordance with Fig 1, the adjusting device 22 of the first hydraulic machine 8 comprises a pressure reducing valve 38. Said valve can be connected by way of a 4/3 directional control valve 40 having in each case a pressure medium chamber of an adjusting cylinder 42 whose piston 44 is coupled to an adjustable cradle of the first hydraulic machine 8 so as to adjust its first displacement volume VHP.
The pressure reducing valve 38 can be actuated in a directly controlled electromagnetic, electrical manner and is coupled by way of a signal line 46 in a signal-communicating manner to the control device 20. The control pressure that is supplied by the connection G is available at a control pressure inlet 50 of the pressure reducing valve 38 by way of a control pressure line 48. A valve body of the pressure reducing valve 38 is pre-stressed by way of a spring into an end position in which a control pressure outlet 52 of the pressure reducing valve 38 is connected in a pressure medium-conveying manner to a tank T. An electromagnet 54 that can be energized by way of the signal line 46 acts against the resilient force. In the case of said electromagnet being energized, the valve body of the pressure reducing valve 38 is displaced from the said end position (control pressure outlet 52 connected to the tank T) into intermediate positions in which the other end position that reveals the fluid connection of the control
- 17 -pressure inlet 50 to the control pressure outlet 52 increasingly gains influence. Accordingly, as the electromagnet 54 becomes further energized, the control pressure at the control pressure outlet 52 increases. The control pressure outlet 52 is connected by way of a control pressure line to the 4/3 directional control valve 40.
Depending upon which position 40a or 40b the said directional control valve is switched to, either one or the other pressure medium chamber of the adjusting cylinder 42 is influenced with pressure medium. The 4/3 directional control valve 40 is consequently used as a valve that determines the drive direction.
Figure 2 illustrates the second exemplary embodiment of the first hydraulic machine 108, wherein the differences with respect to the first exemplary embodiment in accordance with Figure 1 will be explained hereinunder. A pressure reducing valve of the first hydraulic machine 108 in accordance with Figure 2 is embodied in such a manner that the 4/3 directional control valve 40 in accordance with Figure 1 can be omitted. To this end, the pressure reducing valve is embodied as a pressure reducing valve 138 having two individual pressure reducing valves. Each individual pressure reducing valve is allocated a conveying direction of the first hydraulic machine 108 and consequently a drive direction of the drive train 101. The two individual pressure reducing valves of the pressure reducing valve unit 138 comprise in each case a control pressure inlet 150 and a control pressure outlet 152. Each of the control pressure outlets 152 is fixedly allocated to one of the pressure medium chambers of the adjusting cylinder 42. The valve bodies of the two pressure reducing valves are coupled by way of a spring. Each of the pressure reducing valves Mk 02935364 2016-07-07
Depending upon which position 40a or 40b the said directional control valve is switched to, either one or the other pressure medium chamber of the adjusting cylinder 42 is influenced with pressure medium. The 4/3 directional control valve 40 is consequently used as a valve that determines the drive direction.
Figure 2 illustrates the second exemplary embodiment of the first hydraulic machine 108, wherein the differences with respect to the first exemplary embodiment in accordance with Figure 1 will be explained hereinunder. A pressure reducing valve of the first hydraulic machine 108 in accordance with Figure 2 is embodied in such a manner that the 4/3 directional control valve 40 in accordance with Figure 1 can be omitted. To this end, the pressure reducing valve is embodied as a pressure reducing valve 138 having two individual pressure reducing valves. Each individual pressure reducing valve is allocated a conveying direction of the first hydraulic machine 108 and consequently a drive direction of the drive train 101. The two individual pressure reducing valves of the pressure reducing valve unit 138 comprise in each case a control pressure inlet 150 and a control pressure outlet 152. Each of the control pressure outlets 152 is fixedly allocated to one of the pressure medium chambers of the adjusting cylinder 42. The valve bodies of the two pressure reducing valves are coupled by way of a spring. Each of the pressure reducing valves Mk 02935364 2016-07-07
- 18 -comprise a first end position and the control pressure that prevails at the valve body of the control pressure outlet 152 and the force of the spring act in the direction of said first end position. In this first end position, the control pressure outlet 152 is fluid connected to the Tank T. In a second end position of the respective pressure reducing valve, the control pressure inlet 150 is connected to the control pressure outlet 152. Intermediate positions between the end positions are possible. The force of the respective electromagnet 154 of the individual pressure reducing valves is effective into the second end position. The electromagnets 154 are connected in a signal-communicating manner to the control device 20 by way of a signal line 46a or 46b.
The operating principle according to which the pressure p is controlled is common for the two exemplary embodiments. It follows from this that the control pressure pst that is provided at the respective control pressure outlet 52; 152 to the adjusting cylinder 42 with regard to the respective selected drive direction leads to an increase of the first displacement volume VHp of the first hydraulic machine 8;
108. This is counteracted in each case by the then higher of the two working pressures PA, PB in the working lines 10, 12.
In the two illustrated exemplary embodiments, this is achieved by virtue of a corresponding rotation of the respective swash plate of the first hydraulic machine 8;
108. As a result of this type of construction, the respective working pressure PA or pB as a function of the control pressure pstis known in the form of a characteristic field that is stored in the control device 20.
The operating principle according to which the pressure p is controlled is common for the two exemplary embodiments. It follows from this that the control pressure pst that is provided at the respective control pressure outlet 52; 152 to the adjusting cylinder 42 with regard to the respective selected drive direction leads to an increase of the first displacement volume VHp of the first hydraulic machine 8;
108. This is counteracted in each case by the then higher of the two working pressures PA, PB in the working lines 10, 12.
In the two illustrated exemplary embodiments, this is achieved by virtue of a corresponding rotation of the respective swash plate of the first hydraulic machine 8;
108. As a result of this type of construction, the respective working pressure PA or pB as a function of the control pressure pstis known in the form of a characteristic field that is stored in the control device 20.
- 19 -One example of such a characteristic field is illustrated in Figure 3. In accordance with Figure 3, the working pressure p and its allocated adjusting current I of the electromagnet 54 of the hydraulic machine 8 in accordance with Figure 1 or of one of the electromagnets 154 of the first hydraulic machine 108 in accordance with Figure 2 is stored in the control device 20 in dependence upon the first rotational speed nHP of the first hydraulic machine 8; 108.
The control device 20 continuously monitors the pressure medium temperature Ton by way of the temperature sensing unit 30. If the value of said pressure medium temperature is outside a designated range that is stored in the control device, a start-up criterion for an operating phase of the hydrostatic transmission 4; 104 with a limited working pressure p is fulfilled. Accordingly, the working pressure is limited by way of the control device 20 in dependence upon the rotational speed. In accordance with the characteristic field in accordance with Figure 3, a value that is not to be exceeded for the adjusting current Iilm for the electromagnets 54, 154 is then produced for an assumed rotational speed rim, of the first hydraulic machine 8; 108 and an assumed working pressure plIm = p3. By taking into consideration the requirements of the user, the rotational speed nHp of the first hydraulic machine 8; 108 and the stored permissible maximum working pressure pmax in the operating phase, the control device thus in accordance with the invention by way of limiting the adjusting current I to Ilim provides protection for the transmission 4; 104 against wear and damage. Only when the termination criterion is fulfilled, in this case the pressure medium temperature Toil achieves the required, designated range, is the operating phase terminated by way of the control device 20 and the
The control device 20 continuously monitors the pressure medium temperature Ton by way of the temperature sensing unit 30. If the value of said pressure medium temperature is outside a designated range that is stored in the control device, a start-up criterion for an operating phase of the hydrostatic transmission 4; 104 with a limited working pressure p is fulfilled. Accordingly, the working pressure is limited by way of the control device 20 in dependence upon the rotational speed. In accordance with the characteristic field in accordance with Figure 3, a value that is not to be exceeded for the adjusting current Iilm for the electromagnets 54, 154 is then produced for an assumed rotational speed rim, of the first hydraulic machine 8; 108 and an assumed working pressure plIm = p3. By taking into consideration the requirements of the user, the rotational speed nHp of the first hydraulic machine 8; 108 and the stored permissible maximum working pressure pmax in the operating phase, the control device thus in accordance with the invention by way of limiting the adjusting current I to Ilim provides protection for the transmission 4; 104 against wear and damage. Only when the termination criterion is fulfilled, in this case the pressure medium temperature Toil achieves the required, designated range, is the operating phase terminated by way of the control device 20 and the
- 20 -working pressure p can now be adjusted to higher than the hitherto limit value pfirn=
A hydrostatic transmission is disclosed for a drive train wherein a control pressure is effective at a first hydraulic machine of the transmission, said hydraulic machine being operated as a hydraulic pump, in a direction in which the first displacement volume is increased and a working pressure of the transmission that is dependent upon this adjustment is effective in the opposite direction, so that the working pressure can be controlled by way of a control device of the transmission by means of changing the control pressure. An operating phase is parameterized in the control device during which by way of the control device the working pressure and/or a first rotational speed of the first hydraulic machine is or are limited to a fraction of an allocated nominal value. Furthermore, a hydrostatic drive train having this transmission and a method for controlling said transmission are also disclosed.
A hydrostatic transmission is disclosed for a drive train wherein a control pressure is effective at a first hydraulic machine of the transmission, said hydraulic machine being operated as a hydraulic pump, in a direction in which the first displacement volume is increased and a working pressure of the transmission that is dependent upon this adjustment is effective in the opposite direction, so that the working pressure can be controlled by way of a control device of the transmission by means of changing the control pressure. An operating phase is parameterized in the control device during which by way of the control device the working pressure and/or a first rotational speed of the first hydraulic machine is or are limited to a fraction of an allocated nominal value. Furthermore, a hydrostatic drive train having this transmission and a method for controlling said transmission are also disclosed.
- 21 -List of reference numerals 1; 101 Drive train 2 Drive machine 4; 104 Hydrostatic transmission 8; 108 First hydraulic machine 10, 12 Working line 14 Second hydraulic machine 16 Drive shaft 18 Drive shaft Control device
22; 122 First adjusting device 24 Second adjusting device 26 Rotational speed sensor 15 28 Signal line Temperature sensor 32, 34 Signal line 36 Pressure limiting valve 38; 138 Pressure reducing valve; Pressure reducing 20 unit 4/3 Directional control valve 40a 40b Switched position 42 Adjusting cylinder 44 Adjusting piston 25 46; 46a, 46b Signal line 48 Control pressure line 50; 150 Control pressure inlet 52; 152 Control pressure outlet 54; 154 Electromagnet P, PA, PB Working pressure Pnom Nominal working pressure Piirn Working pressure limit Pst Control pressure VHP First displacement volume VHM Second displacement volume 11Hp First rotational speed nriom Nominal rotational speed HM Second rotational speed Adjusting current Ilim Adjusting current limit Toil Pressure medium temperature
Claims (19)
1. A hydrostatic transmission for a drive train, said transmission comprising a first hydraulic machine that can be coupled to a drive machine and comprises an adjustable first displacement volume and is arranged together with at least one second hydraulic machine of the transmission in a hydraulic circuit and said second hydraulic machine can be coupled to an output of the drive train, wherein a control pressure of the transmission at the first hydraulic machine, is effective in a first direction in which the first displacement volume is increased and a working pressure of the second hydraulic machine that is dependent upon this adjustment is effective in a second direction opposite the first direction, so that the working pressure can be controlled by way of a control device of the transmission by means of changing the control pressure, characterized in that an operating phase of the transmission is parameterized in the control device during which by way of the control device at least one of the working pressure and a first rotational speed of the first hydraulic machine is or are controlled at a fraction of an allocated nominal value.
2. The transmission according to Claim 1, wherein the operating phase is an inflow phase or an outflow phase of the transmission.
3. The transmission according to Claim 1 or 2, wherein a termination criterion is stored in the control device and the operating phase can be terminated by way of the control device on the basis of said termination criterion being fulfilled.
Date reçue/Date received 2023-02-17
Date reçue/Date received 2023-02-17
4. The transmission according to Claim 3, wherein the termination criterion is a duration of the operating phase.
5. The transmission according to claim 3 or 4, wherein the at least one process variable is one of a plurality of process variables, and the termination criterion is defined in dependence upon at least one of the plurality of process variables of the transmission.
6. The transmission according to Claim 5, wherein the termination criterion is that the at least one of the plurality of process variables lies within a designated operating range that is parameterized in the control device.
7. The transmission according to Claim 5 or 6, wherein the at least one of the plurality of process variables comprises a pressure medium temperature of the hydraulic circuit of the transmission.
8. The transmission according to Claim 7, having multiple sensing sites for sensing the pressure medium temperature, wherein the termination criterion is assessed in dependence upon at least two of the ascertained pressure medium temperatures.
9. The transmission of any one of claims 1 to 8, wherein a start-up criterion is stored in the control device and the operating phase can be started by way of the control device on the basis of said start-up criterion being fulfilled.
Date reçue/Date received 2023-02-17
Date reçue/Date received 2023-02-17
10. The transmission according to Claim 9, wherein the start-up criterion is a start-up procedure of the transmission or the drive train.
11. The transmission according to claim 9 or 10, wherein the start-up criterion is defined in dependence upon at least one start-up process variable of the transmission.
12. The transmission according to Claim 11, wherein the at least one start-up process variable lies outside a designated range that is parameterized in the control device.
13. The transmission according to Claim 11 or 12, wherein the at least one start-up process variable is a pressure medium temperature of the hydraulic circuit of the transmission.
14. The transmission according to Claim 13, having multiple sensing sites for sensing the pressure medium temperature, wherein the start-up criterion is assessed in dependence upon at least two of the ascertained pressure medium temperatures.
15. The transmission according to any one of claims 1 to 14, wherein a characteristic field of the control pressure or a characteristic field of a signal that corresponds thereto in dependence upon the working pressure is stored in the control device for controlling the working pressure.
Date reçue/Date received 2023-02-17
Date reçue/Date received 2023-02-17
16. The transmission according to any one of claims 1 to 15 having a pressure control device or a pressure reducing device that can be controlled by way of the control device by means of an electrical desired value signal of the control pressure, and that is embodied in such a manner that the control pressure is essentially proportional to the desired value signal.
17. A hydrostatic drive train comprising the hydrostatic transmission according to any one of claims 1 to 16.
18. A method for controlling the hydrostatic transmission as defined in any one of claims 1 to 16, characterized by the step of:
- limiting the at least one of the working pressure and the first rotational speed to the fraction of the allocated nominal value during the operating phase by way of the control device.
- limiting the at least one of the working pressure and the first rotational speed to the fraction of the allocated nominal value during the operating phase by way of the control device.
19. The method according to claim 18 comprising the steps of:
¨ starting the operating phase by way of the control device as soon as a start-up criterion is fulfilled;
and ¨ terminating the operating phase by way of the control device as soon as a termination criterion is fulfilled.
Date reçue/Date received 2023-02-17
¨ starting the operating phase by way of the control device as soon as a start-up criterion is fulfilled;
and ¨ terminating the operating phase by way of the control device as soon as a termination criterion is fulfilled.
Date reçue/Date received 2023-02-17
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102015212727.3 | 2015-07-08 | ||
| DE102015212727.3A DE102015212727A1 (en) | 2015-07-08 | 2015-07-08 | Hydrostatic transmission, traction drive with the transmission and method of controlling the transmission |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2935364A1 CA2935364A1 (en) | 2017-01-08 |
| CA2935364C true CA2935364C (en) | 2023-09-26 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2935364A Active CA2935364C (en) | 2015-07-08 | 2016-07-07 | Hydrostatic transmission, drive train having the transmission and method for controlling the transmission |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP3115651B1 (en) |
| CA (1) | CA2935364C (en) |
| DE (1) | DE102015212727A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102017212921A1 (en) * | 2017-07-27 | 2019-01-31 | Robert Bosch Gmbh | Variable Displacement hydraulic machine, gearbox assembly with hydraulic machine, and method of controlling gearbox assembly |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100188882B1 (en) | 1993-06-30 | 1999-06-01 | 토니 헬샴 | Automatic preheating system for an internal combustion engine and hydraulic pump |
| DE102005037619B4 (en) | 2005-08-09 | 2020-07-09 | Brueninghaus Hydromatik Gmbh | Control valve unit with change stop |
| US7686737B2 (en) * | 2005-09-30 | 2010-03-30 | Kubota Corporation | Speed control structure and method for work vehicle |
| JP4990334B2 (en) * | 2009-09-03 | 2012-08-01 | 株式会社小松製作所 | Work vehicle |
| DE102011120665B4 (en) | 2011-12-09 | 2023-12-21 | Robert Bosch Gmbh | Method for operating a drive system comprising a hydrostatic drive unit |
| EP2767739B1 (en) | 2013-02-19 | 2018-10-24 | Dana Rexroth Transmission Systems S.r.l. | Power-split transmission for a vehicle propulsion system, method for controlling the transmission |
-
2015
- 2015-07-08 DE DE102015212727.3A patent/DE102015212727A1/en not_active Withdrawn
-
2016
- 2016-05-30 EP EP16171875.4A patent/EP3115651B1/en active Active
- 2016-07-07 CA CA2935364A patent/CA2935364C/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| EP3115651B1 (en) | 2018-01-31 |
| CA2935364A1 (en) | 2017-01-08 |
| EP3115651A1 (en) | 2017-01-11 |
| DE102015212727A1 (en) | 2017-01-12 |
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