This application claims priority from German Application Serial No. 103 14 324.6 filed Mar. 28, 2003.
The invention concerns a hydrodynamic converter with a primary clutch for the power train of a motor vehicle, particularly of a working machine, such as of a wheel loader of a lift truck or of a dumper.
Since the introduction of automatic transmissions, hydrodynamic converters have been the connecting element between a prime mover and the transmission proper. A converter makes possible, on one hand, a comfortable jolt-free start through the slip and at the same time dampens irregularities of rotation of the internal combustion engine. On the other hand, the fundamental increase of the torque makes available a great starting torque.
According to the prior art, a hydrodynamic converter is comprised of an impeller, a turbine wheel, the reaction element (guide wheel, stator) and the oil needed for torque transmission.
The impeller, which is driven by the engine, moves the oil in the converter to a circular current. Said oil current hits upon the turbine wheels where it is turned around in flow direction.
In the hub area, the oil leaves the turbine and arrives at the reaction element (guide wheel) where it is again turned around and thus fed to the impeller in the proper flow direction.
Due to the reversal, in the stator a torque generates whose reaction increases the turbine torque. The ratio of turbine torque to pump torque is designated as torque increase. The greater the rotational speed difference between pump and turbine, the greater the torque increase which has the maximum magnitude when the turbine is stationary. As the turbine rotational speed increases, the height of the torque consequently decreases. If the turbine rotational speed rises to about 85% of the pump rotational speed, the torque increase=1, that is, the turbine torque is equal to the pump torque.
The stator, which props itself toward the transmission housing via the freewheel and the stator shaft, flows freely in this state in the current and the freewheel is rolled over.
From this point on, the converter works as pure flow clutch. During the conversion, the stator remains still and is propped toward the housing via the freewheel.
Converters are known from the prior art which comprise one converter lock-up clutch and one primary clutch, said primary clutch being inserted between engine and converter and the lock-up clutch between engine and transmission.
Such converters are usually provided for vehicles which perform works at very low speeds but can also move at high speeds. Within the scope of DE 195 21 458 Al is described, by way of example, a converter with lock-up clutch and primary clutch. According to the prior art, there are, respectively, provided for converter lock-up clutch and primary clutch its own pressure supply and its own valve unit.
Converters are also known which comprise one converter lock-up clutch and are especially used in transportation vehicles such as dumpers or cranes. On the other hand, converters with primary clutch are used in working machines like wheel loaders or lift trucks.
The problem on which this invention is based is to provide a hydrodynamic converter in which the pump is detachably connectable via a primary clutch with the output from the engine.
A hydrodynamic converter for the power train of a motor vehicle is accordingly proposed which comprises one pump, one turbine connected with the transmission input shaft and one stator (guide wheel) and in which the pump is detachably connectable with the engine input via a primary clutch, the latter being located in the transmission.
According to the invention, the primary clutch is mounted in the transmission so that the converter can be subsequently inserted, it being possible that the converter is one with/without freewheel, the same as with/without lock-up clutch.
The primary clutch can be designed here as positive clutch or negative clutch actuatable by transmission system pressure, or as clutch actuatable by converter pressure. Depending on the design, the clutch can be lubricated via the transmission system or via the converter circuit.
The invention will now be described, by way of example, with reference to the accompanying drawings in which:
In
The primary clutch PK is sealed relative to the oil of the converter circuit; the clutch is lubricated and cooled from the transmission system, the cooling oil then flowing off into the transmission sump. In the embodiment shown in
In
According to the invention, grooves 17 are provided in the friction lining which convey the oil outwardly where it is collected in the deep interstices of the spline. The oil is inwardly guided into radial grooves in the end disc and the inner disc carrier and then can flow axially to the converter into the gap between pump hub 8 and converter shell 7. In addition, the oil can flow via holes in the gap between pump hub 8 and stator 9 in the converter. The primary clutch is closed under pressurization, the closing pressure of the transmission system being superposed on the converter inner pressure.
Within the scope of the embodiment shown in
As shown in
According to the invention, the primary clutch can also be actuated via the converter pressure. The higher the engine rotational speed, the higher becomes the through flow resistance and the higher is then the piston force or the clutch torque.
In those primary clutches in which the primary clutch is actuated via the converter pressure, said converter pressure acts against the pistons by lowering the pressure behind the piston 11 so that the piston presses upon the disc set and closes the clutch. Such an embodiment is the object of
In
The primary clutches provided in the embodiments of
As shown in
In all embodiments sensors can be installed, for example, one pressure sensor 14 to detect the pressure before the piston 11, or a rotational speed sensor 15 to detect the pump rotational speed. This is shown by way of example in
With the exception of the embodiments in
Number | Date | Country | Kind |
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103 14 324 | Mar 2003 | DE | national |
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Number | Date | Country |
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1 550 973 | Oct 1969 | DE |
2 006 955 | Sep 1970 | DE |
77 18 674 | Sep 1978 | DE |
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870863 | Jun 1961 | GB |
Number | Date | Country | |
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20040188207 A1 | Sep 2004 | US |