Hydrodynamic transmission unit with hydrodynamic circuit

Abstract

Hydrodynamic transmission unit (1) comprising a primary bladed impeller (2) and a secondary bladed impeller (3), which are designed such that the two impellers (2, 3) are rotatably mounted and form an oil-fillable working chamber in which torque can be transmitted from one impeller to the other impeller by forming a flow, further comprising an oil circuit with an oil reservoir (7), an inlet line (4) and an outlet line (5), wherein the working chamber can be supplied with oil via the inlet line (4) and wherein oil can be discharged from the working chamber via the outlet line (5), wherein a shut-off valve (20) is provided in the inlet line (4), and the outlet line (5) and the inlet line (4) are connected to each other in such a way that oil can circulate from the working chamber without having to pass through the oil reservoir (7), wherein the shut-off valve (20) is positioned between the connection point of the outlet line (5) with the inlet line (4) and the working chamber, and wherein a control device is provided which is designed to close the shut-off valve (20) when the oil is to be drained from the working chamber into the oil reservoir (7). characterized by that the shut-off valve (20) comprises a valve piston (23) which is made entirely or at least predominantly of plastic, and which in particular has a piston surface (23a) made of plastic

Description

[0001] The invention relates to a hydrodynamic transmission unit comprising a primary bladed impeller and a secondary bladed impeller, which are designed such that the two impellers are rotatably mounted and form a working chamber which can be filled with oil and in which torque can be transmitted from one impeller to the other impeller by forming a flow, further comprising an oil circuit with an oil reservoir, an inlet line and an outlet line, wherein the working chamber can be supplied with oil via the inlet line and wherein oil can be discharged from the working chamber via the outlet line.

[0002] Such hydrodynamic transmission units are known, for example, as turbo couplings, retarders, or torque converters. In order to control torque transmission, the working chamber must be able to be filled and drained with oil in a controlled manner. For draining purposes, the prior art provides a drain valve in the drain line or in a connecting line between the drain line and the oil reservoir. DE 102004015706 A1 describes a hydrodynamic coupling that can be drained via a drain valve in an additional connecting line between the drain line and the oil reservoir. The disadvantage is that the draining time with such an arrangement is relatively long and that an additional line is required.

[0003] From DE 10 2006 050 759 A1 an oil circuit with an actuating device for a hydrodynamic starting unit is known.

[0004] Further hydrodynamic couplings are known from DE 100 46 828 A1, DE 195 03 295 A1 and DE10 2008 034 974 A1.

[0005] Also known from DE 100 46 833 A1 is a hydrodynamic coupling which comprises means for filling and emptying and means for setting the pressure, wherein it is provided that oil can circulate from the working chamber without being led through the oil reservoir.

[0006] The object of the invention is to further develop such a gear unit so that emptying is faster and easier.

[0007] The object of the device is achieved according to the invention by a gear unit according to claim 1. Further advantageous features of the inventive embodiment, which further improve the device, can be found in the corresponding subclaims. The gear unit according to the invention is characterized in that a shut-off valve is provided in the inlet line, and that the outlet line and the inlet line are connected to one another in such a way that oil from the working chamber can circulate without having to be passed through the oil reservoir, wherein a control device is provided which is designed such that the shut-off valve is closed when the oil from the working chamber is to be emptied into the oil reservoir.

[0008] In this design, the shut-off valve is positioned between the connection point of the drain line and the supply line and the working chamber. This ensures proper functioning during emptying without the need for an additional line or valve.

[0009] The key advantage of the inventive solution is that the closed shutoff valve in the supply line prevents further oil from being sucked into the working chamber from the line and the oil circuit during the draining process due to the rotation of the primary impeller. This rotation also forces the oil from the working chamber into the drain line to the oil reservoir. This drains the working chamber significantly faster than is possible with a conventional additional line with a quick-drain valve on the drain side. Furthermore, this creates a short, closed circuit.

[0010] Oil is understood here to mean any operating fluid, which can also be coolant or water, for example.

[0011] Filling is the process by which the empty or partially filled working chamber is further filled and the oil quantity in the oil circuit is increased by additional oil from the oil reservoir. Conversely, emptying is the process by which the fill level in the working chamber is reduced and oil is drained from the oil circuit into the oil reservoir.

[0012] Rapid emptying is especially necessary when the retarder's braking effect is no longer required after use. This protects an existing brake element that secures the secondary impeller. If the hydrodynamic transmission unit is used as a clutch upstream of a downstream automated manual transmission, it is also advantageous if the hydrodynamic clutch can be emptied as quickly as possible after upshifting to relieve the friction elements in the manual transmission.

[0013] In another advantageous embodiment, a heat exchanger is installed in the drain line, and the oil circuit is designed so that the oil flows through the heat exchanger when draining the working chamber. The heat exchanger is necessary to dissipate the heat generated during operation from the circuit. With previous solutions, the heat exchanger must be bypassed during draining, and the oil is drained directly into the oil reservoir via an additional line opened by the drain valve.

[0014] Furthermore, it is advantageous if there is no drain valve in the drain line or in an additional line between the drain line and the oil reservoir.

[0015] Preferably, a common riser pipe is provided that connects both the supply line and the drain line—i.e., the closed circuit—to the oil reservoir. During filling, oil is forced through this riser pipe into the supply line, and during emptying, oil is drained from the drain line into the oil reservoir. This allows for a very simple arrangement.

[0016] It is also advantageous if the inlet and outlet lines open into the working chamber near the primary impeller, particularly so that the inlet line opens in the radially inner area of ​​the working chamber, i.e., approximately at the inner circumference, and the outlet line opens in the radially outer area of ​​the working chamber, i.e., at the outer circumference. This utilizes the pumping effect of the rotation of the primary impeller for draining and also for oil circulation in a closed circuit.

[0017] Preferably, the oil reservoir is designed so that air pressure (py) can be applied to the oil within it, forcing oil into the oil circuit. The air pressure py determines the oil quantity in the oil circuit and thus the fill level in the working chamber. This allows for efficient control of the transmission unit's function.

[0018] In a further advantageous embodiment, the primary impeller is connected to an input shaft in a rotationally fixed manner, and the secondary impeller is connected to an output shaft in a rotationally fixed manner via a freewheel. In addition, a clutch is preferably provided which, when engaged, can connect the input shaft and the output shaft. The lock-up clutch thus allows the hydrodynamic transmission unit to be bypassed in the load path when not needed—for example, when the starting or gearshift process is complete. Additionally, the transmission unit can be designed as a starting clutch-retarder unit for a vehicle. A braking element is provided which can lock the secondary impeller to the housing. Rapid emptying is particularly important in such arrangements.

[0019] In order to be able to control the shut-off valve as effectively and quickly as possible, it is preferably designed as a pneumatically controlled valve.

[0020] In a particularly preferred embodiment, the shut-off valve is designed with a valve piston that has at least two seals arranged one behind the other at a distance from the other to separate the oil and air. This allows the valve piston to move quickly while still ensuring reliable separation of air and oil. The sealing effect is improved, and the valve piston still moves freely, allowing the shut-off valve to close particularly quickly. Possible seals include, for example, an O-ring, a radial shaft seal, a quad ring, or a piston ring.

[0021] Furthermore, the shut-off valve preferably has a cylinder bushing or a valve housing that encloses the valve piston and has an oil outlet opening positioned so that it lies between the two seals, whether the shut-off valve is closed or open. This allows oil that has passed through the oil-side seal to be drained away without reaching the air side. The sealing effect is further improved.

[0022] It is advantageous if the oil outlet opening is connected to the oil reservoir via a leakage line, so that the leakage oil remains in the oil circuit.

[0023] According to the invention, the shut-off valve is designed with a valve piston made entirely or at least predominantly of plastic, and in particular, with a plastic piston surface. Due to its low weight, the piston can be moved more quickly and is also easier and cheaper to manufacture.

[0024] Further advantageous embodiments of the invention are explained using exemplary embodiments with reference to the drawings. The features mentioned can be advantageously implemented not only in the illustrated combination, but also individually combined with one another. The figures show in detail: Fig. 1 Schematic representation of a transmission unit according to the invention with oil circuit Fig. 2 Schematic of another transmission unit according to the invention as a starting clutch retarder unit for a vehicle Fig. 3 Detailed view of the shut-off valve for a gear unit according to the invention

[0025] The figures are described in more detail below. Like reference numerals indicate like or similar parts or components.

[0026] In Fig. Figure 1 shows a hydrodynamic transmission unit 1, which can be used, for example, as a clutch, particularly as a starting clutch for a vehicle. The primary impeller 2 and the secondary impeller 3 form a roughly toroidal working chamber, in which blades are arranged in the respective impellers so that, when filled with oil, torque can be transferred from one impeller to the other.

[0027] The oil is supplied via the supply line 4 and removed via the drain line 5. To fill the working chamber, oil is forced from the oil reservoir 7 into the working chamber via the riser line 6 and the supply line 4. For this purpose, a pressure py is applied to the compressed air line 9, which acts on the oil sump in the oil reservoir 7. During operation, the oil circulates through the closed circuit between the supply line 4 and the drain line 5 and is cooled in the heat exchanger 8.

[0028] If the working chamber needs to be drained, the quick-action shut-off valve 20 is pneumatically actuated via the compressed air line 22, closing it. This prevents the rotating action of the impeller from sucking in any more oil from line 4 and entering the working chamber. At the same time, the rotation drains the oil from the working chamber into the oil reservoir via the drain line 5 and the riser line 6. This enables fast and reliable draining, even at higher impeller speeds.

[0029] Fig. Figure 2 shows a structural diagram of a hydrodynamic transmission unit according to the invention, which is designed as a starting clutch-retarder unit. The existing oil circuit is not shown here and can, for example, be arranged as in the exemplary embodiment in Fig. 1 must be executed.

[0030] The primary impeller 2 is connected to the input shaft 14 in a rotationally fixed manner. The secondary impeller 3 is connected to the output shaft 15 via a freewheel. The freewheel blocks one direction of rotation, thus creating a rotationally fixed connection, and releases the other direction of rotation, allowing the shaft and impeller to rotate independently of each other. A clutch 11 and a torsional damper 13 are also provided. The clutch 11 acts as a lock-up clutch and connects the input shaft 14 and output shaft 15, bypassing the hydrodynamic unit. To enable the retarder function, a braking element 10 is provided that can lock the secondary impeller 3 to the housing 16. In vehicle applications, an automated manual transmission is usually present on the output side, which is not shown here. On the input side, there is a connection to the drive motor.Particularly when upshifting in a manual transmission, when the speed in the hydrodynamic transmission unit is reduced, rapid emptying of the working chamber is important to protect the friction elements in the manual transmission. Rapid emptying is also important when shifting gears after braking via the retarder. This protects the brake element 10.

[0031] Fig.Figure 3 shows an exploded view of the shut-off valve 20 for a transmission unit according to the invention. The valve piston 23 has, among other things, a piston surface 23a and a sealing surface 23b. The sealing surface 23b closes the valve when closed; in the illustrated embodiment, it is conical. The valve piston 23 is preferably made of plastic. Alternatively, only the sealing surface 23b can be made of plastic. This is particularly advantageous over the known valve pistons made of steel or other metal with a rubberized sealing plate, as it is simpler and cheaper to manufacture. The piston 23 has two seals 24 and 25. The two seals 24, 25 are designed as round seals and are arranged one behind the other on the valve piston 23, spaced apart from one another. They separate the air and oil sides particularly effectively. Also visible are the cover plate 29 and the spring 28, which serves as a return spring.

[0032] The cylinder sleeve 27 serves as the valve housing. It has an oil outlet opening 26, which is positioned so that when the valve is assembled, it is always located between the two seals 24, 25, both in the closed and open positions. This allows oil that has penetrated past the seal 24 to be drained away without reaching the air side. During operation, a leakage line is preferably connected to the oil outlet bore 26, which drains the leaked oil into the oil reservoir. The inventive design of the shut-off valve 20 enables a reliable sealing effect to be achieved while simultaneously allowing good mobility of the piston 23. This allows for particularly good media separation between the oil side and air side of the shut-off valve. List of reference symbols 1 gear unit 2 primary impeller 3 secondary impeller 4 Inlet line 5 Drain line 6 riser pipe 7 Oil reservoir 8 heat exchangers 9 Compressed air line for py 10 Brake element 11 Clutch 12 Freewheel 13 torsion dampers 14 Input shaft 15 Output shaft 16 housings 20 Shut-off valve 21 Leakage line 22 Pneumatic line 23 valve pistons 23a Piston surface 23b Sealing surface 24 first seal 25 second seal 26 Oil outlet opening 27 Cylinder liner 28 spring 29 Cover plate

Claims

[1] Hydrodynamic transmission unit (1) comprising a primary bladed impeller (2) and a secondary bladed impeller (3), which are designed such that the two impellers (2, 3) are rotatably mounted and form a working chamber which can be filled with oil and in which torque can be transmitted from one impeller to the other impeller by forming a flow, further comprising an oil circuit with an oil reservoir (7), an inlet line (4) and an outlet line (5), wherein the working chamber can be supplied with oil via the inlet line (4) and wherein oil can be discharged from the working chamber via the outlet line (5), wherein a shut-off valve (20) is provided in the inlet line (4), and that the outlet line (5) and the inlet line (4) are connected to one another in such a way that oil from the working chamber can circulate without having to be guided through the oil reservoir (7), wherein the shut-off valve (20) is positioned between the connection point of the outlet line (5) with the inlet line (4) and the working chamber, and wherein a control device is provided which is designed such that the shut-off valve (20) is closed when the oil from the working chamber is to be emptied into the oil reservoir (7), characterized by , that the shut-off valve (20) comprises a valve piston (23) which is made entirely or at least predominantly of plastic, and which in particular has a piston surface (23a) made of plastic [2] Gear unit (1) according to claim 1 characterized bythat a heat exchanger (8) is present in the drain line (5) and that the oil circuit is designed in such a way that the oil flows through the heat exchanger (8) when the working chamber is emptied. [3] Gear unit (1) according to one of the preceding claims characterized by that there is no drain valve in the drain line (5) or in an additional line between the drain line (5) and the oil reservoir (7). [4] Gear unit (1) according to one of the preceding claims characterized by that there is only one common riser pipe (6) connecting the inlet pipe (4) and the outlet pipe (5) to the oil reservoir (7). [5] Gear unit (1) according to one of the preceding claims characterized bythat the inlet line (4) and the outlet line (5) open into the working chamber in the region of the primary impeller (2), in particular such that the inlet line (4) opens in the radially inner region of the working chamber and the outlet line (5) opens in the radially outer region of the working chamber. [6] Gear unit (1) according to one of the preceding claims characterized by that the oil reservoir (7) is designed in such a way that an air pressure (py) can be applied to the oil therein, so that oil is pressed into the oil circuit. [7] Gear unit (1) according to one of the preceding claims characterized by that the primary impeller (2) is connected in a rotationally fixed manner to a motor or drive, in particular via a drive shaft (14), and the secondary impeller (3) is connected in a rotationally fixed manner to an output shaft (15) via a freewheel (12). [8] Gear unit (1) according to claim 7 characterized bythat a clutch (11) is present which, when closed, can connect the input shaft (14) and the output shaft (15) to one another. [9] Gear unit (1) according to claim 8 characterized by that the transmission unit (1) is designed as a starting clutch-retarder unit for a vehicle, wherein a braking element (10) is provided which can lock the secondary impeller (3) on the housing (16). [10] Gear unit (1) according to one of the preceding claims characterized by that the shut-off valve (20) is designed as a pneumatically controlled valve. [11] Gear unit (1) according to claim 10 characterized by that the shut-off valve (20) comprises a valve piston (23) which has at least two seals (24, 25) arranged one behind the other at a distance from one another for separating oil and air. [12] Gear unit (1) according to claim 11 characterized byin that the shut-off valve (20) comprises a cylinder bushing (27) or a valve housing which encloses the valve piston and has an oil outlet opening (26) which is arranged such that it lies between the two seals (24, 25) when the shut-off valve (20) is closed as well as when it is open. [13] Gear unit (1) according to claim 12 characterized by that the oil outlet opening (26) is connected to the oil reservoir (7) via a leakage line (21).

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