Patent Application
20170327099
The present invention relates to a working medium circuit for a hydrodynamic machine that is arranged in a drive train with a drive motor, as installed in motor vehicles, for examples buses and trucks. In each case, such hydrodynamic machines include a working medium circuit through which the working medium can circulate.
Such retarders are known to the expert in various designs. The retarder essentially comprises a stator and a rotor which together form a toroidal working chamber. The working medium circuit essentially comprises a working medium container, an inflow line, an emptying line and a cooler. Means are also provided by way of which in a first operating state, in particular the braking mode, the working medium can be moved out of the working medium container into the working chamber, and in a second operating state, in particular the non-braking mode the working medium can be moved out of the working chamber back into the working medium container.
In the braking mode, a circular flow is created in the working medium circuit by way of which the working medium that is heated in the working chamber by the hydrodynamic flow is pumped to the cooler and from there back into the working chamber.
Ventilation of the hydrodynamic circuit occurs via an aerating and ventilating unit that is installed in the working medium circuit and vents into the atmosphere. Aerating and ventilating is especially important in order to be able to quickly switch from one operating state to the other and in order to prevent intermixing of air with the working medium, wherein during switching the working chamber must either be vented or aerated. Various means are known for preventing the working medium from getting into the surroundings. Moreover, contamination of the working medium which would cause a reduction in the operational readiness must be prevented.
Known working media for retarders are oils or aqueous solutions, in particular cooling water from the vehicle's cooling circuit. Due to increased demands, it is necessary to prevent leakage of working medium into the environment and to extend the change intervals for the working medium.
What is needed in the art is a working medium circuit that provides improved operational readiness.
The present invention a working medium circuit for a hydrodynamic machine provides. Additional embodiments and possible solution variations are described in the dependent sub-claims.
The working medium circuit for a hydrodynamic machine which is arranged in a drive train with a drive motor includes at least one each rotor blade wheel and stator blade wheel which are arranged in a common housing and together form a toroidal working chamber. The working chamber can be filled with and emptied of working medium in order to switch the hydrodynamic machine on and off. The working medium circuit includes a working medium container, an inflow line, an emptying line, a heat exchanger and devices by way of which the working medium can be moved out of the working medium container into the working chamber in a first operating state, in particular the braking mode. The working medium can be moved out of the working chamber back into the working medium container in a second operating state, in particular the non-braking mode. The circulation of the working fluid is brought about by the rotor blade wheel.
It is moreover provided that for aerating and ventilating, the working chamber is connected at least indirectly via a ventilating line with an unpressurized chamber which has a ventilating device vis-à-vis the surroundings and in which working medium can collect.
The working medium of the hydrodynamic machine can moreover be oil and the chamber can be the oil container of the drive motor or the transmission. This simplifies aerating and ventilating of the working chamber. Provision may thus be made to link the aeration and ventilation of the working chamber with the air space of the transmission or drive motor, thereby utilizing the aerating and ventilating device of the transmission or drive motor also for the working chamber.
The connection can occur internally via the retarder housing, transmission housing or more specifically the internal combustion engine housing or via an external line. This solution is conceivable for retarders having a common oil supply with the transmission or the internal combustion engine, as well as for retarders having a separate oil pan or oil supply. The oils that are used for transmission and retarder or combustion engine and retarder are herein selected such that they are miscible with one another.
In the embodiment with the separate retarder oil pan, the chamber can moreover be connected indirectly via a compensating line with the working medium container. The oil volumes of the two oil supplies can thus be balanced with one another via an internal channel or an external line.
The chamber may be located at a geodetically higher level than the working medium container and may be connected with the working medium container in such a way that the working medium flows out of this atmospherically connected container into the working medium container due to gravity, so that no separate pump is required.
Furthermore, a valve may be arranged in the compensating line in order to be able to influence the flow into the working medium container and in order to be able to interrupt this connection.
It may also be provided that the device for switching between operational modes include a pump. By way of the pump the working chamber can be filled with working medium on the one hand, and on the other hand the leakage losses that occur in the braking mode can be compensated for.
In another embodiment, the pump includes at least three control ranges—a first control range during filling of the hydrodynamic machine, a second control range during braking mode, and a third control range during non-braking mode.
In one embodiment, a filter may be located upstream from the pump, so that the oil quality required for retarder operation is always ensured.
Moreover, in the case of hydrodynamic oil retarders that share a common oil supply with the transmission, the pump may be a displacement pump, located on the retarder or transmission side, by way of which both units are supplied with oil.
Furthermore, a switchable quick-draining line may be provided for rapid emptying of the working chamber.
In addition, an alternative is also conceivable whereby the chamber includes the oil container of the drive motor and the working medium container and whereby a common container is created.
In the non-braking operating mode of the retarder, the pump can be connected/switched with the oil circuit in such a way that—for cooling—an oil stream is pumped continuously from the chamber of the drive motor or the transmission and/or the working medium container through the heat exchanger of the retarder.
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
The working medium circuit consists of a working medium container 5, an inflow line 13, an emptying line 14, a heat exchanger 6, as well as devices 20, 11 by way of which in a first operating state, in particular the braking mode, the working medium can be moved out of working medium container 5 into working chamber 2, and in a second operating state, in particular the non-braking mode the working medium can be moved out of working chamber 2 back into working medium container 5. The circulation of the working medium is caused by rotor blade wheel 18. In this embodiment, it is provided that the retarder adjustment occurs by way of compressed air 20 that acts upon the working medium in working medium container 5 and through which the working medium is pressed into working chamber 2 via a standpipe 21.
Via the shifting position of the valves of valve unit 10, the lines are switched for the filling mode, the braking mode or the emptying mode. Thus, the circulation in the braking mode occurs via inflow line 13 and emptying line 14 via heat exchanger 6 and working chamber 2.
Alternatively, the embodiment illustrated in
Ventilation of working chamber 2 occurs via ventilating line 3 through which the connection from the center of working chamber cross section 2 into chamber 4 is established. An oil discharge device can be provided in chamber 4, and ventilation occurs via venting valve 9.
An oil discharge device can be located before or integrated in aerating and ventilating unit 9.
To compensate for oil losses that occur via the ventilating line into chamber 4, a compensating line 8 with a switching valve 7 is provided. The chamber, or at least the oil level in the chamber, may be arranged geodetically higher than the working medium container, or more specifically the oil level thereof, so that the level compensation can occur without additional devices.
For this purpose, the outlet of displacement pump 11 is connected with emptying line 14 of the working medium circuit. This connection causes a pressure equilibrium during operation between the outlet of displacement pump 11 and the outlet of the hydrodynamic circuit. This influences the fill level of the hydrodynamic circuit and thereby the provided retarder braking torque.
An adjustable as well as a non-adjustable pump can be used as the displacement pump. An adjustable pump offers the advantage that during non-braking operation the mechanical power consumption of pump 11 can be reduced.
With hydrodynamic oil retarders that share a common oil supply with the transmission, retarder-specific or transmission-specific displacement pumps can be dispensed with in the case of transmissions with their own pump 11. This one pump then assumes the oil supply for lubrication and cooling of the transmission, as well as the supply of the working medium in working chamber 2 that is required for the braking operation.
A heat exchanger 6 is built into the working medium circuit for cooling, wherein heat exchanger 6 can also be used for cooling the common oil supply.
While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2015 201 910.1 | Feb 2015 | DE | national |
This is a continuation of PCT application No. PCT/EP2016/050870, entitled “WORKING MEDIUM CIRCUIT FOR A HYDRODYNAMIC MACHINE”, filed Jan. 18, 2016, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2016/050870 | Jan 2016 | US |
| Child | 15668960 | US |
