DE2707098A1 - TRANSMISSION FOR A MOTOR VEHICLE - Google Patents

Description

The invention relates to hydraulic transmissions for motor vehicles, in particular a transmission with a clutch with direct torque transmission, which is in a torque converter or a fluid coupling is arranged.

Theoretically, the turbine of the torque converter must be at Increase in the speed of the internal combustion engine rotate at the same speed as the pump, so that a direct drive between the output shaft of the prime mover and the transmission input shaft is achieved. In practice, however, there is always one Torque converter slip, or more precisely, a slight difference in speed between the pump, which is driven directly by the internal combustion engine, and the turbine, which is driven by the pump wheel. It follows that the torque converter is not able to provide an exact 1: 1 torque ratio between the output shaft the prime mover and the transmission input shaft. Such a loss in torque transmission leads to an undesirable uninterrupted loss of fuel.

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It is already known to arrange a clutch with direct torque transmission in the housing of a torque converter, this clutch enabling a direct drive connection between the output shaft of the internal combustion engine and the transmission input shaft without the use of a transmission transmission through the torque converter. However, the direct drive enabling clutch is designed such that it is only engaged after the third gear or fastest gear is engaged, for example when the transmission is a three forward gear transmission. This means that a direct drive connection is only established when the internal combustion engine is accelerated further after switching on the fastest gear. It follows that a gearbox equipped with this clutch works practically like an ordinary gearbox with four forward gears, but without a clutch with direct torque transmission, its construction and function as well as its manufacturing costs being comparable to conventional gears and therefore only a small one compared to conventional gears Owns advantage. Furthermore, there is the disadvantage that the driver and the occupants of the vehicle are exposed to unpleasant bumps when the transmission is shifted three times, namely from 1st to 2nd gear, from 2nd to 3rd gear and from 3rd to direct ( fastest) gear if the transmission is equipped with four forward gears.

The invention is directed to creating a transmission for a motor vehicle which has a clutch with direct torque transmission, which is arranged in a hydraulic torque converter, and which avoids the disadvantages described above. The invention is also directed to improving a transmission of the type described above in such a way that the clutch with direct torque transmission is engaged at the same time when a shift from a lower to a higher gear or to the fastest gear occurs, while it is simultaneously disengaged when the Transmission is shifted down to lower gears. The invention is also directed to creating a transmission of the type described above, with

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which the fuel consumption of the internal combustion engine can be reduced that the slip of the torque converter is avoided with the help of the coupling with direct torque transmission. The transmission described above is also intended to be a have a simpler construction so that the manufacturing and operating costs are reduced. And finally, the transmission should of the type described above allow a reduction in the shock frequencies during switching.

According to the invention, a transmission for a motor vehicle with a drive machine is proposed, the output shaft of which with a transmission input shaft via a hydraulic clutch device for transmitting the torque from the output shaft is connected to the transmission input shaft, the transmission according to the invention being characterized by hydraulically controllable Means for engaging at least two forward gears, one forward gear for a low vehicle speed and a forward speed for a high vehicle speed is provided by a hydraulic circuit for control the hydraulic control devices and for the optional engagement of the forward gear for the low or high vehicle speed, by a hydraulically actuated frictional engagement device with which a direct drive connection can be produced between the output shaft of the drive machine and the transmission input shaft without the hydraulic clutch device is, and by a control device, which both with the hydraulic circuit and with the frictional engagement device is in flow communication so that the frictional engagement device is simultaneously engaged when a Shifting from the low vehicle speed gear to the high vehicle speed gear occurs during the Frictional engagement device simultaneously with the shift from the gear for a high vehicle speed to the gear is disengaged for a low vehicle speed.

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According to the invention is therefore within a torque converter housing a friction disk clutch with several disks is provided, which enables a direct torque transmission. I. Furthermore, in a hydraulic control circuit of the transmission is a; Clutch control valve provided, which by the fluid pressure is switched within the control circuit in such a way that the clutch with the direct torque transmission simultaneously is engaged when shifting from the low vehicle speed gear to the high vehicle speed gear occurs while the clutch is being disengaged at the same time as a shift from the high vehicle speed gear into the aisle for low vehicle speed.

Further features, details and advantages of the invention emerge from the following description of an exemplary embodiment based on the drawing. Show in it:

Fig. 1 is a sectional view through part of the drive gear with a coupling according to the invention with direct torque transmission;

Fig. 2 is a schematic representation of the hydraulic control circuit, which is used in connection with the transmission shown in FIG. 1;

3 shows a schematic representation of a control valve according to the invention for the clutch with direct torque transmission, which is used in the hydraulic control circuit shown in Figure 2;

Fig. 4a is a diagram in which the circuit diagram of a conventional Motor vehicle transmission is shown, and

Fig. 4b is a diagram in which the circuit diagram of the invention Transmission is shown.

The transmission shown in FIG. 1 has a drive shaft 1 which is driven by an internal combustion engine, not shown a flywheel 2 attached to the shaft 1, a transmission input shaft 9, a hydraulic torque converter T and a friction disc clutch A for direct torque transmission. The transmission also has a planetary gear set and various engagement elements for an optional frictional

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gene engagement with the corresponding gears of the planetary gear set, although this is not shown in FIG.

The hydraulic torque converter T has three elements in a manner known per se, namely a pump wheel 4 and a turbine 5 and a stator 6. The impeller 4 is connected to the valve 1 and is driven by this, while the turbine 5 is attached to a bushing 10, which in turn is connected to the transmission input shaft 9 is wedged. The stator 6 is attached to a short hollow shaft (no reference number) which has an overrunning clutch 7 is connected to an oil pump 8.

The clutch A with direct torque transmission is arranged within the housing of the torque converter and from a Friction disk clutch formed with a plurality of friction disks, the clutch having a piston 11 and movable in the axial direction has a clutch disc assembly (no reference number). The assembly has clutch drive disks 12 and a retainer plate 14, which rotates with the housing 3 of the torque converter, and driven clutch plates 13, which respectively between the corresponding clutch drive discs 12 or between the corresponding clutch drive disc 12 and the retaining plate. Each of the driven clutch disks 13 has corresponding friction surfaces on both sides. The driven clutch disks are in turn connected to a clutch disk 18 with the help of a torsion spring 17 is connected to a coupling hub 19 which is keyed onto the shaft 9.

The outer surface of the piston 11 bounds with the inner surface of the torque converter 3, a fluid chamber 23, which over a throttle bore 24 which is arranged in the torque converter housing, an elongated axial bore 25 in the shaft 9 and a bore 26 leading to the pump 8 with a housing of a control valve 80 for the clutch with direct torque transmission is related, which will be discussed in detail later.

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To engage clutch A, a hydraulic fluid is supplied via the The previously described bores passed through the valve 80 into the chamber 23. So if the pressure built up in the chamber 23 the Pressure in the torque converter housing exceeds, then the piston 11 is moved axially with respect to the drawing to the right, so that the clutch drive disks 12 are pressed firmly against the driven clutch disks 13 and engage with them rotate together. The torque introduced into the driven clutch disks 13 is then transmitted via the clutch disk 16 and the torsion spring 17 transferred to the shaft 9, so that thereby a direct drive between the motor output shaft and the transmission input shaft is generated.

When the pressure in chamber 23 is below that in the torque converter housing the prevailing pressure drops when all or part of the liquid is drained from this chamber, then the piston 11 moves to the left with respect to the drawing, so that the clutch drive plates 12 of the driven Clutch disks 13 are separated. Then the torque is generated in a manner known per se by means of the torque converter transfer.

In Fig. 2 is a circuit diagram of a known hydraulic Control circuit shown, which is used in an automatic transmission, which has three forward gears and one reverse gear having.

As is known per se, the control circuit basically comprises a pressure regulating valve 60, a manual control valve 61, a first and a second control valve 62, 63, one responsive to the suction pressure Throttle valve 67 and automatic switching valves 64 and The liquid coming from the pump 8 is controlled by the pressure regulating valve 60 set to a suitable line pressure and passes through the belt control valve 61 depending on the manually set switching stage to the corresponding lines. The automatic switching valves are actuated depending on the control pressures which are generated by the control valves in

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Depending on the vehicle speed and the throttle pressure generated by the valve 67 are generated, the latter responds to the pressure prevailing in the intake line of the internal combustion engine. While the switching valve 64 is switching between causes 1st and 2nd gear, the valve 65 causes a shift between 2nd and 3rd gear. The hydraulic shown Circuit also has various hydraulic elements, such as for example the pressure converter valve 67, a servo valve 68 for the valve 67, a solenoid operated valve 69 for downshifting, a second shut-off valve 70, a control valve 71, these hydraulic elements are all known per se, so that a no further description of these parts is required.

The transmission shown also has, as frictional engagement elements, a front clutch 75, a rear clutch 76, and a drum brake 73 and a brake 74 for slow and reverse travel. The front clutch 75 is engaged by being over a line 30 is acted upon with hydraulic fluid while the rear clutch 76 is engaged by having a Line 31 is acted upon with hydraulic fluid. The servo 72 of the drum brake 73 has a load side and a relief side, which are connected to a line 40 and to the line 30, respectively. When the load side is pressurized via line 40, then will a brake band is tightened on an unmarked drum surface so that the brake responds while the brake is released, when the relief side is supplied with pressure via line 30. The slow and reverse brake 74 is also activated attracted and released by liquid pressure, this liquid pressure being supplied through a conduit 41.

If the hydraulic circuit is in operation, then the slow gear or the first forward gear is switched on in that the rear clutch 76 via the line 31 is pressurized. Lines 30 and 40 are both not under fluid pressure. To the middle or second Engaging forward gear, the pressure in lines 31 and

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40 so that the front clutch 76 is engaged and the drum brake 73 is operated. The great or third forward gear is only turned on when both the front clutch 75 and the rear clutch 76 are engaged. if the line 30 is under pressure, then the drum brake solved. To engage reverse gear, the front clutch 75 is engaged and the brake for slow and reverse travel 74 is tightened while the rear clutch 76 is disengaged and the drum brake 73 is released. From the foregoing is it can be seen that only in 3rd gear or with the fastest drive the lines 30 and 31 are both under pressure and the clutches 75 and 76 are indented.

The control valve 80 according to the invention will now be based on FIG for the clutch with direct torque transmission are described, which in the hydraulic shown in FIG Control circuit is used. The valve essentially consists of a valve slide 81 with two control webs 81a and 81b, which in an elongated bore 89 with essentially the same Diameter is slidably mounted. While one axial end of the bore 89 is closed, the other is axial End with the line 30 shown in FIG. 2 via a connection 86 in connection. The bore also has a connection 88, which is connected to the already mentioned bore 26, and a connection 84, which is connected to the one shown in FIG line 31 shown is connected, the two connections can be connected to one another by an optional axial movement of the valve slide 81. The valve slide 81 is of a The spring 82 is loaded in such a way that it is pressed towards the connection 86 which is in communication with the line 30. A sequence 90 is also provided through which the liquid from the bore 89 is derived.

The above-described control valve for the clutch with direct torque transmission works as follows. During the When you switch from 2nd to 3rd gear, the fluid pressure builds up in the line 31 and thus via the connection 84 in the bore

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on. As soon as the shift to 3rd gear is completed, the fluid pressure also reaches the line via the switching valve 65 30, so that the connection 86 is also under pressure and the pressure acts on the control surfaces of the control web 81b. The valve slide 81 is then moved to the right with respect to FIG. 3 against the force of the spring 82 until a connection between terminals 84 and 88 is established. The liquid then passes through the connection 88 into the bore 26 and thus into the liquid chamber 23, which is shown in FIG. The clutch with direct torque transmission is then indented in the prescribed manner.

As soon as a downshift from 3rd to 2nd gear occurs, the fluid is drained from port 86, and consequently the valve slide 81 is moved by the spring 82 with respect to FIG. 3 to the left. As a result, the connection 88 connected to the drain 90 so that the liquid is drained from the chamber 23 through the bore 26.

As has already been stated, those shown in FIG. 2 are available Lines 30 and 31 under constant pressure as long as the fastest or 3rd forward gear is switched on. Consequently can the fluid connection of the control valve for the clutch with direct torque transmission according to FIG. 2 in such a way be selected that the connection 86 is connected to the line 31, while the connection 84 is connected to the line 30 is.

4a and 4b are based on diagrams corresponding operating curves of a conventional transmission with a clutch with direct torque transmission or the transmission according to the invention compared to each other. As can be seen from the As can be seen from the diagrams, the switching takes place practically three times in the previously known transmission, namely between the 1st and 2nd gear, between 2nd and 3rd gear and between 3rd and direct gear. On the other hand, switching takes place at the transmission according to the invention only twice instead, as shown in FIG. 4b, since switching between the 2nd and

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essentially simultaneously with switching between the 2. and the direct walk takes place. The various advantages resulting therefrom are already in the description above have been mentioned and do not need to be mentioned again at this point.

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Claims (8)

PATENTANVVALTC A, & RÜN £ CKER _'- pi .-: nc * H. KINKELOEY W. STOCKMAIR κ. SCHUMANN DR ΛΒΛ NAT- WL-PHVS P. H. JAKOB d * fi_-wo. G. BEZOUO 8 MUNICH 22 MAXIMILIANSTRASSK * 3 P 11,345 {077 Claims Transmission for a motor vehicle with a prime mover, the output shaft of which is connected to a transmission input shaft via a hydraulic clutch device for the transmission of the torque is coupled from the output shaft of the prime mover to the transmission input shaft by hydraulically controllable devices (60 to 80) for engaging at least two forward gears, wherein a forward gear for a low vehicle speed and a forward gear for a high vehicle speed is provided by a hydraulic circuit (Fig.2) for controlling the hydraulic control devices and for optional engagement of the forward gear for the low or high vehicle speed, by a hydraulically actuated Frictional engagement device (A), with which a direct drive connection between the output shaft of the prime mover and the transmission input shaft without the hydraulic one Coupling device can be produced, and by a control device (80), which both with the hydraulic Circuit as well as with the frictional engagement device is in a flow connection, so that the frictional (o ··) aaasaa tslbx oi-aon τιιιακωΜί month t «lbkopibr« i » engagement device is simultaneously engaged when a Shifting from the low vehicle speed gear to the high vehicle speed gear occurs while the final engagement device simultaneously with the shift from the gear for a high vehicle speed is disengaged into the gear for a low vehicle speed. 2. Transmission for a motor vehicle with a prime mover, the output shaft of which with a transmission input shaft via a hydraulic clutch device for transmitting the torque from the output shaft of the drive machine to the Transmission input shaft is coupled, characterized by a set of engagement elements with which a frictional engagement for engaging several forward gears is made possible, with one forward gear for a high vehicle speed is provided by a hydraulic circuit (see Fig. 2) through which the Engagement element can be acted upon with a controlled pressure fluid are to be selectively engaged or disengaged, the circuit having two leads (30, 31) which are under pressure when the forward gear is switched on for the high vehicle speed is, by a hydraulically controlled Rexbschlußeingriffseinrichtung (A), with which a direct connection between the output shaft of the prime mover and the transmission input shaft (9) without the hydraulic clutch device (T) can be produced, wherein the locking engagement device has a pressure fluid chamber (23) and is engaged is when there is a high fluid pressure in the chamber, while it is disengaged when that prevailing in the chamber Fluid pressure falls below a predetermined level, and through a hydraulically controllable valve (80), which in the hydraulic circuit is arranged and a valve slide (81) which is movable such that it a fluid connection between one of two lines (30, 31) with the pressure fluid chamber (23) of the frictional 709834/0355 Intervention device (A) produces if in both lines the fluid pressure prevails while he interrupts the fluid connection, so that the pressure fluid from the Pressure fluid chamber of the frictional engagement device is derived when the fluid pressure in one of the two lines is relieved. 3. Transmission according to claim 2, characterized in that the hydraulic clutch device has a hydraulic torque converter (T). 4. Transmission according to one of claims 1 to 3, characterized in that the hydraulically operated Frictional engagement device (A) a friction disc clutch having a plurality of discs, which is arranged in a torque converter housing (3) and has a piston (11), which is axially movable by the different pressure acting on its two opposite sides. 5. Transmission for a motor vehicle with a prime mover, its output shaft with a transmission input shaft via a hydraulic coupling device for transmitting the torque is coupled from the output shaft of the prime mover to the transmission input shaft, marked by a set of engagement elements, with which a frictional engagement for the engagement of several Forward gears are enabled, with a forward gear for a high vehicle speed is provided by a hydraulic circuit (see Fig. 2) through which the Engaging elements can be acted upon with a controlled pressure fluid are / to be selectively engaged or disengaged, the circuit having a first Has line (31) which is under pressure in each forward gear, and a second line (30) which is only in the gear for the high vehicle speed is under pressure, through a hydraulically controlled frictional engagement device (A), with which a direct connection between the output shaft the prime mover and the transmission input shaft (9) without 70P33A / 03 55 the hydraulic clutch device (T) can be produced, the frictional engagement device being a pressure fluid chamber (23) and is engaged when there is high fluid pressure in the chamber while it is disengaged is when the prevailing liquid pressure in the chamber falls below a predetermined level, and by a hydraulically controllable valve (80) which is arranged in the hydraulic circuit and has a valve slide (81), which is movable in such a way that it provides a fluid connection between the first line (31) and the pressurized fluid chamber (23) of the frictional engagement device (A) produces when the fluid pressure is simultaneously in the second line (30) prevails while he interrupts the fluid connection so that the pressure fluid from the Chamber of the frictional engagement device (A) is derived when the fluid pressure in the second line is relieved is. 709834/0355