DE1680650B2 - Hydraulic control device for an automatically shifting motor vehicle gearbox with three forward gears - Google Patents

Description

6. Hydraulic control device according to claim 5, characterized in that the further Connection line (156) has a connection with an auxiliary piston (402, 404) of the backflow valve (388) which its spring (398) braced against the valve body (390) is supported.

A hydraulic control device for an automatic .Sf. tig switching motor vehicle gearbox with three Forward gears of the type covered by the claims is, for example, from FR-PS 12 02 888 known. The servo device is provided for the friction brake resulting in the slow gear, and the back pressure valve comprises two valve bodies, each loaded by a biasing spring, which in the at the release chamber of this servo device connected supply line are connected in series and the control pressures dependent on the vehicle speed and the engine torque to be influenced. With the two valve bodies of the backflow valve, depending on the level of these control pressures associated throttle points in the supply line made effective or be bypassed in order to influence the time required for the complete emptying of the Release chamber of this servo device when shifting down from middle gear to slow gear is needed.

This consequently the application of the friction brake correspondingly delaying effect of the backflow valve is further supplemented in the known control device by an even upstream of one unpressurized drain line of the 1,2-switching valve provided Another throttle point, in front of which there is also a back pressure in the then to this outlet line connected supply line of the servo device for a friction clutch resulting in the middle gear builds up so that their loosening in appropriate coordination on da :; delayed tightening the friction brake is also delayed in time. When upshifting from slow gear to middle corridor, however, unfolds this through the

various throttling points triggered delaying effect by then bypassing the main pressure of the back pressure valve via the check valve at the same time the tightening chamber and the release chamber of the Servo device for the low speed friction brake and the lowering device for the Middle gear resulting friction clutch is allocated.

The invention is based on the object of developing the known control device so that the Tighten the friction brake, which results in the middle gear, both when upshifting gears from slow gear as well as when downshifting from direct gear, adapting to the respective Driving conditions is dampened. This damping effect should be independent of the 3.2 downshift be attainable from whether the shift of the middle gear by a pushing vehicle Reversal of the drive direction triggered in direct gear takes place or with the assistance of one for one Forced downshifting of the relevant kick-down valve.

Due to the solution to this object according to the invention according to the characterizing part of claim 1 provided measures is achieved that regardless of the shift direction of the gears only one of the Pressure force of the biasing spring for the valve body of the back pressure valve depending on a back pressure accordingly predetermined and controllable size in the release chamber of the servo device for the Middle gear resulting friction brake must be built up before the friction brake is fully applied will. Since the back pressure builds up progressively and therefore the blocking position of the valve body against the Force of the biasing spring is left accordingly increasingly in favor of the release position thereby also the tightening of the friction brake increasingly stronger, so that until it is fully applied a sufficient damping for a desired smooth gear change is achieved.

With the further development of the invention covered by claim 2, it is possible to make the backflow valve ineffective, for example, in reverse gear or also when the transmission is set for permanent shifting of the slow gear. Through the measure of claim 3, it is possible to modify the damping effect when the friction brake is applied depending on the shift direction of the gears and, for example, to specify a back pressure of about 0.7 at for the 1.2 upshift, while for the 3.2 downshift, a back pressure of about 2 at is required. This modifying effect can also be used advantageously by the measure of claim 4 for a forced downshifting of the gears in order to obtain a very smooth gear change in this way. By means of the measures of claims 5 and 6, it is finally possible to optimally adjust the application of the friction brake to very specific driving conditions in order to obtain different deceleration effects for the different switching directions.

An embodiment of the invention is shown schematically in the drawing and is described below described in more detail. It shows

1 shows an overall representation of a motor vehicle change-speed transmission, for its automatic switching a hydraulic control device according to the invention is provided,

2A and 2B the circuit diagram of this hydraulic Control device,

Fig. 3 shows the piston valve of the one shown in Fig. 2B Hand ventiis in a 90 ° rotated position and

4 shows the backflow valve shown in FIG. 2A according to a modified version.

The hydraulic control device is for a motor vehicle change gearbox with three forward gears provided by an internal combustion engine 10 with a carburetor 12 and one with its crankshaft connected hydrokinetic torque converter 16 is driven. Through the impeller 18 of the Torque converter 16 becomes a power steering pump 24

ΙΊ driven which both the converter and the Hydraulic control device is supplied with pressurized oil, which from a sump 124 via a suction line 126 is sucked in. Furthermore, the turbine wheel 20 of the converter 16 is connected to a drive shaft 32 of the transmission

2V) , which is surrounded by a hollow shaft 26 connected to the transmission housing 28 , on which the stator 22 of the converter 16 is arranged via a one-way brake 30 which allows rotation of the stator only in one direction of rotation

2 ^r ) of the stator locks in the opposite direction of rotation.

The drive shaft 32 connected to the turbine wheel 20 of the converter 16 is via one in all three Forward clutch 36 and engaged in forward gears

jn one designed as a friction disk clutch like this one further friction clutch 38, which is only engaged in direct gear and reverse gear, with an output shaft 72 of the transmission connected through which, for example, the rear wheels of the vehicle concerned are driven. Via the forward clutch 36, a direct connection is established with the Hohirad 40 of a first planetary gear set 42 of the change gear, which still has planetary gears 68 on one with the output shaft 72 connected planetary gear carrier 70 and a sun gear 46 which is attached to a The engine shell 44 which can be connected to the drive shaft 32 via the friction clutch 38 is formed. That Sun gear 46 is a second set of planet gears 48 in common, with the sun gear 46 and with a ring gear 74 also connected to the output shaft 72 meshing planet gears 76 on a Planetary gear carrier 78 are arranged, which is connected to the transmission housing via a one-way brake 96 is.

The engine shell 44 and thus the sun gear 46 are through a middle gear of the gearbox The resulting friction brake 50 can be braked, and a servo device 54 is provided for its actuation is that a cylinder 56 and one in this

^r r> sliding servo piston 58, which divides the cylinder into a tightening chamber 60 and a release chamber 62. As soon as the pressurization of the tightening chamber 60 controlled by the hydraulic control device, that of the release

w) exceeds chamber 62, then the brake band of the friction brake 50 is then against one with the Engine shell 44 connected to the brake drum is attracted, while on the other hand the friction brake 50 is released when the brake band supported on a fixed abutment via a linkage 64 transmitted pressurization of the release chamber 62 predominates. The planetary gear carrier 78 can similarly via a brake drum 80 formed on it and a

The brake band 82 of a further friction brake that interacts with this is braked, which is actuated by means of an associated servo device "84 for a tightening in slow gear and in reverse gear, but is otherwise released, whereby the connection with the gearbox housing via the Eünwegbremse% exists. The servo device 84 comprises a servo piston 88 displaceable in a cylinder 86, the application of pressure in a tightening chamber 90 via a linkage 92 to the brake band 82 of this friction brake Upshifting of the change-speed gearbox is prevented and the i ^r > slow gear is constantly maintained, just as the gearbox also remains shifted to reverse gear when the brake band 82 is tightened against the brake drum 80 with the clutch 38 engaged

When the brake band 82 is released, the transmission only remains in its slow gear until the friction brake 50 resulting in the middle gear is applied with the assistance of the hydraulic control device. It is possible to change from this middle gear to a direct gear by engaging the friction clutch 38 and releasing the friction brake 50 synchronously with it. Conversely, it is possible to change from the direct gear to the middle gear if the friction clutch 38 is disengaged again and the friction brake 50 is applied again, and this downshift can be continued with a change to slow gear if the driving conditions are appropriate, if the friction brake 50 is then used again is resolved. ϊ>

The hydraulic control device comprises a pressure control valve 104 arranged in the delivery line 118 of the servo pump 24, the valve body 106 of which is displaceable by the servo pressure against a spring 128 and is provided with four control collars 108, 110, 112 and 114, which cooperate with corresponding sieve edges of the valve bore 118 . The delivery line 118 is connected to the valve bore 116 at the level of the control collars 110, 112 and 114 so that, due to the differential area formed by the control collars 108 and 110 in cooperation with the force of the valve spring 128, an equilibrium position for the valve body 106 results as soon as the Main pressure is built up in the control circuit of the control device. ^{An unpressurized outlet 120 connected to the transmission sump 124 via a 5} ″ connecting line 122 also contributes to this build-up of the main pressure, the relevant control edge of which cooperates with the control collar 114 in order to create the ^r > ⁵ main pressure from the servo pressure depending on the mutual overlap ratio , which is then fed to the other parts of the control device via a main pressure line 164.

A connection line 132 with the torque converter ^{h (l} K) is also connected to the pressure regulating valve 104 and is opened by the sleeve collar 112 before the nozzle collar 114 can open the connection to the unpressurized outlet 120. Thus, the delivered by the servo pump 24 pressure oil passes earlier in the converter 16, wherein the ^Μ Driickbcgrcnzung of Scrvodmckcs in the Verbindungslcitung 132 Sichcrhcits check valve is installed 140th Another check valve 13f> is installed in a supply line 134 leading to the various lubrication systems, which is branched off from the connecting line 132.

In the lower end of the valve bore 116 of the pressure control valve 104, a bush 144 is inserted, which a biasing piston 146 for a spring 162 receives which at its other end on the valve body 106 of the Pressure control valve is supported. The biasing piston 106 has three control ports 148, 150 and 152, of which the two control connections 150 and 152 form a differential area, which via connection bores in the socket 144 with a connection line 154 to a pressure control valve 370 connection, the is connected to the other side via a line 156 to a backflow valve, as long as the biasing piston 146 assumes the illustrated lower position. This connection between the two lines 154 and 156, however, is interrupted when in one of the difference areas between the control collars 148 and 150 through a connection hole of the socket 144 connected line 158 the main pressure dem Biasing piston 146 is fed, which is only the case in reverse and then has the consequence that with the cooperation of the spring 162, the valve body 106 of the pressure regulating valve 104 is moved into a position, in which the main pressure is set to a value that is higher than that of the forward gears. One The only other way to increase the main pressure with the assistance of the preloading piston 146 is to increase the main pressure instead of when the vehicle is pushing and the drive is reversed at high speeds when the free-running valve 406 is then switched on, the main pressure via a connection 160 at the end face comes to the control collar 148 of the biasing piston 146 to which otherwise only the a line 272 brought up and mediated by the free-wheeling valve 406 acts as a throttle pressure, which is a generated by a throttle pressure valve 261, the engine torque corresponding Control pressure is.

The main pressure line 164 is led to a manual valve 166 which comprises a manually displaceable valve body 172. The valve body 172 has several control collars 174,176,178,180,182,184,186 and 188, which interact with corresponding control edges of the valve bore 170 in order to produce different control sequences in the various switching positions of the valve body 172 as a result of different pressure distribution to the individual parts of the control device via the individual connection bores of the manual valve 166 . If the valve body 172 of the manual valve 166 is consequently adjusted to the "P" position, the transmission is switched to a park position. In the "R" position of the valve body 172, the transmission is shifted into reverse gear, in the "N" position in a neutral position, in the "Dl" position in a shift position that allows automatic switching only between slow gear and middle gear , in the "D2" position in a shift position that allows automatic switching between all three forward gears, and finally in the "L" position in a shift position in which the transmission is set for permanent shifting of the slow gear. The valve body 172 is shown in the relative position assumed in the switching position "N" , in which the main pressure line 164 through the two control bundles 170 and 184 for a transmission of the main pressure to the various switching valves

the control device is blocked.

When the valve body 172 is set to the "R" switch position, the main pressure line 164 is connected to the connecting line 158 leading to the pretensioning piston 146 and to a connecting line 198, 228 to the servo device 84, through which the reverse gear producing friction brake for one Tightening of the brake band 82 is operated. The connecting line 198, 228 is routed via the 1,2-switching valve 203 , which also has a direct connecting line 190 with the manual valve 106 , which in the switching position "D2" of the valve body 172 comes into connection with the main pressure line 164 , while the lines 158 and 198 are emptied. In this switching position "D2" of the valve body 172, which, like all other sound positions, can be fixed on the valve body by the interaction of a spring-loaded locking pin 200 (FIG. 3) with a corresponding recess 202 , a connecting line 192 with a 2, 3-switching valve 235 is connected to the main pressure line 164 and a connecting line 194, 226 with the servo device, which is provided for actuating the forward clutch 36 . In the switching position “Dl”, the connecting line 190 with the 1,2-switching valve 203 is emptied, and only the connecting line 192 with the 2,3-switching valve 235 and the connecting line 194, 226, which is also connected to the 1,2-switching valve 203 with the servo device for the forward clutch 36 are then connected to the main pressure line 164 . In the "L" switch position of the valve body 172 , only the latter connection line 194, 226 is connected to the main pressure line 164 via the manual valve 166 , while all the other connection lines are then depressurized either via one or the other end of the valve bore 170 or a still provided pressure-less Outlet 196 are emptied.

The connecting line 190 with the 1 ^ switching valve 203 opens into its valve bore 208 at the joint between the two parts 204 and 206 of a valve body which is displaceable in the valve bore 208 . The upper part 206 of the valve body has two control collars 218 and 220 of different diameters, to the differential area of which a connecting line 222 with a Drossclmodulierventil 256 is connected, which the throttle pressure brought up via a branch line 258 of the throttle pressure line 272 and increased by means of a throttle pressure booster valve 294 built into this branch line also modulated for transmission to the 2, 3 switching valve 235. The other part 204 of the valve body of the 1,2-switching valve 203 on the other hand comprises the four control collars 210, 212, 214 and 216 and is biased by a biasing spring 224 in a key for both valve body parts high position, wherein the force acting in this direction, the biasing force of the spring 224 is supplemented by the control collar 210 end face acting main pressure of the manual valve 166 in the connecting line 198.228 for which prevails in the switching position "R" of the valve body 172 to the servo device 84 to the reverse resultant friction brake. In the meantime, the two valve body parts 204 and 206 are also in the switch position "L" of the valve body 172 of the manual valve 166 by the main pressure acting on the control collar 210 in the illustrated elevated position, so that the 1,2-switching valve 203 is blocked for an automatic upshift of the transmission into middle gear. In all other cases, the pretensioning force of the spring 224 is supplemented by the main pressure acting on the differential area between the two control collars 210 and 212 , which is branched off at this point from the connecting line 194, 226 with the servo device for the forward clutch 36 and during the downward movement of the valve body part 204 by the

ίο the main pressure brought in via the connecting line 190 as well as the modulated throttle pressure brought in via the connecting line 222 and a control pressure corresponding to the driving speed on the front side at the control collar 220 of the valve body part 206 , which is via a connecting line 234 with a regulator arranged on the output shaft 72 100 (Fig. 1), is then relieved via the line 228 to a pressureless drain 230 up to the moment at which the branch line branched off from the connecting line 194, 225 is closed by the control collar 212. With this pressureless outlet 230 , on the other hand, a connection to the tightening chamber 60 of the servo device 54 for the friction brake 50 resulting in the intermediate gear has a connection which is replaced by a connection between the line 232 and the line 194, 226 as the valve body part 204 moves downwards the control collar 214 of the pressureless outlet 230 is closed or is then opened synchronously with it for a connection with the line 228 .

The 2, 3 switching valve 235 comprises a valve body 236 which is displaceable in a valve bore 238 and which has a plurality of control collars 240, 242, 244 and 246 which interact with corresponding control edges of the valve bore 238 . The connecting line 192 with the manual valve 166 opens into the valve bore 238 at the level of the two control collars 242 and 244 which form a differential area, whereby the main pressure brought in via the connecting line 192 exerts a force on the valve body 236 supplemented by the force of a biasing spring 248 , which the also zoom out via the line 234 and the end face next to the control collar 240 for applying pressure regulator, that is the dependent of the driving speed control pressure counteracts. If the valve body 236 is pressed down from the illustrated high position, the annular surface between the two control collars 242 and 244 then comes into connection via a connected branch line 250 with the connection line 158 of the manual valve 166, which is only pressurized in reverse gear, and then over this connecting line to be emptied. In the high position of the valve body 238 shown , on the other hand, there is a connection via a connecting line 254 to the supply line 252, 366 leading to the release chamber 62 of the servo device 54 for the friction brake 50 resulting in the intermediate gear, from which there is also a supply line 252 ' for the servo device for the reverse gear and the direct gear resulting friction clutch 38 is branched off. In the high position of the valve body 236 of the 2, 3 switching valve 235 shown , both the release chamber 62 of the servo device 54 of the friction brake 50 al resulting in the middle gear, as well as the servo device of the friction clutch 38 giving the direct gear, are emptied via the connecting line 158, 250 254 of the manual valve 166 , while on the other hand

then the relevant supply lines 252, 366 and 252 'with the connection line 192 brought up main pressure when the Ventilkörpe.- 236 of the 2,3-switching valve 235 a Occupies a low position. In the deep position, the two lines 192 and 254 have a connection as soon as the Branch line 250 of the connection line 158 is blocked by the control collar 244 of the valve body 236. in the The rest of the action on the valve body 236 is still the throttle pressure brought in via the line 258, the is modulated by the throttle modulating valve 256 by the biasing spring loading the valve body 236 248 is supported on the valve body of this throttle modulating valve 256. The one on line 258 The throttle pressure introduced thus supplements the biasing force of the spring 248, which is further enhanced by the The main pressure introduced via a connecting line 320 with a kick-down valve 308 is supplemented can be as soon as this kick-down valve 308 for a forced downshift of the transmission when Driving in direct gear is actuated. The valve body 236 of the 2,3-switching valve 235 is consequently then through this brought up via the line 320 main pressure is pressed into the illustrated high position, so that it consequently then to a loosening of the direct gear resulting friction clutch 38 and to a tightening of the middle one Gear resulting friction brake 50 comes.

The throttle valve 261, which is decisive for the formation of the throttle pressure, comprises one with several control banks provided valve body 260, its displacement in a valve bore 268 by a servo device 278 is controlled, which is based on the intake manifold pressure supplied via a connection line 292 Internal combustion engine 10 responds. The main pressure line 164 is also connected to the throttle valve 261 connected, which is controlled by the valve body 260 connection to the outlet line 272 of the Throttle valve 261 receives, whereby the receives in this outlet line 272 of the throttle valve 261, whereby the in this outlet line prevailing throttle pressure is directly dependent on the intake manifold pressure Internal combustion engine 10 and thus dependent on the relevant drive engine torque.

The throttle booster valve built into branch line 258 to boost the throttle pressure 294 comprises a valve body 2% with the two control collars 298 and 298 forming a differential area 300, which interact with corresponding control edges of the valve bore 302. The valve body 296 is loaded by a biasing spring 306, so in the illustrated position of the valve body by its Control collar 298 a connected branch line of the main pressure line <64 is blocked, the other hand to increase the throttle pressure in the connecting line leading to the throttle modulating valve 256 258 is opened as soon as the throttle pressure brought in via line 272 hits the valve body 296 moves against the force of the bias spring 306. The increase in the throttle pressure in the connection line 258 to the throttle modulating valve 256 takes place only when the one formed by the throttle valve 261 Throttle pressure in line 272 exceeds a certain value, while until this is reached of a certain value, the throttle pressure would otherwise be supplied to the throttle modulating valve 256 without such an amplification is forwarded.

The branch line 258 of the throttle pressure line 272 leading to the throttle modulating valve 256 is also connected connected to the kick-down valve 308, which has a valve body which is displaceable in a valve bore 316 310 with two control collars 312 and 314, which is still loaded by a biasing spring 318. Of the Control collar 314 of valve body 310 normally blocks the connection to line 258, the meanwhile, it is opened as soon as the valve body 310 against the force of the preload spring 318 for a forced downshifting of the gears is shifted,

ίο what a corresponding mechanical connection with the throttle valve of the internal combustion engine 10 consists. In this case, the throttle pressure is also in the The outlet line 272 of the throttle valve 261 is so large that it then causes the valve body 296 of the throttle pressure booster valve 294 is shifted against the force of its biasing spring 306 in a position in which its Control collar 298 has opened the connection of the main pressure line 164. The main pressure thus arrives Via the line 320 connected to the emptied connection line 198 of the manual valve 166 until then, to the 2,3-switching valve 235, then adding the connecting line 322 with the connecting line 198 through the control collar 312 of the valve body 310 is closed. Consequently the valve body 236 of the 2, 3 switching valve 235, as already described, is then moved into the illustrated Pressed high position, which is decisive for a 3.2 downshift. The next is via the connection line 320 main pressure is also fed to the 1,2-switching valve 203 via the connecting line 222,

jo which also affects both valve body parts 204 and 206 in the sense of a forced 2.1 downshift will. The main pressure supplied to the switching valves through the intermediary of the kick-down valve 308 is at the same time because of the involvement of the Drosscklruckver-

j <> starch valve 294 superimposed with the throttle pressure, thus greater independence from the machine speed which influences the level of the main pressure and thus a more optimal influence on the decisive factors for the forced downshifting of the gears

to switching points of the sound valves is reached. the In the drive of the servo pump 24, the control of the main pressure is dependent on the engine speed by the internal combustion engine 10, since this means that everything for the servo pump and the pressure control valve 104 significant manufacturing tolerances have a direct influence on the regulated by the pressure control valve Take the pressure height of the main pressure.

In to the tightening chamber 60 of the servo device 54 for the friction brake resulting in the middle gear 50 leading supply line 232, 367 is also installed a damping valve 354, which a by a biasing spring 362 loaded valve body with two control collars 356 and 358, which with corresponding control edges of the valve beaning 360 cooperate. To the valve bore 360 is furthermore, the throttle pressure line 272 is connected to supplement the force of the pretensioning spring 362 as well as in Height of the control collar 358 attached to the release chamber 62 of the servo device 54 for the middle gear

Bo resulting friction brake 50 connected supply line 252,366, so that when this supply line is pressurized to release the Friction brake 50 of the valve body of the 2,3-Dämpfveniils 354 from the illustrated high position against the Force of the pretensioning spring 362 and the throttle pressure brought in via the throttle pressure line 272 is moved down. This then becomes the tightening chamber 60 through the control collar 358

The leading supply line 232, 367 is progressively interrupted, so that to the extent that the servo device for the friction clutch 38 producing the direct gear is actuated simultaneously via the supply line 252 ', the friction brake 50 producing the middle gear is released. The 2,3 damping valve 354 thus dampens the engagement of the friction clutch 38 resulting in the direct gear, whereby, depending on the level of the throttle pressure brought in via the line 272, a corresponding delay occurs when the friction brake 50 is released, which can only then be regarded as complete, when the connecting line 367 between the 2,3 damping valve 354 and the tightening chamber 60 has received a connection to the supply line 252, 366. If the throttle pressure in the throttle pressure line 272, which is also connected to the 2,3 damping valve 354, is very high, the friction clutch 38 resulting in the direct gear will already be engaged before the> o friction brake 50 resulting in the middle gear begins to be released, while on the other hand if the throttle pressure is sufficiently low, the friction brake 50 will release practically synchronously with the engagement of the friction clutch 38. This guarantees a correspondingly soft 2.3 upshift for both low and high engine torque. In addition, a biasing piston 368 for the biasing spring 362 is inserted into the valve bore 360, which, by connecting this lower end of the valve bore 360 to the connection line 198 of the manual valve 166, is subjected to the main pressure as soon as this connection line 198 is in the reverse gear of the transmission and also in which switching position »L« of the manual valve, which results in a permanent shift of the slow gear, receives the main pressure r>. This then ensures that the valve body of the 2,3 damping valve 354 remains pressed into the upper position shown, so that there is then no connection between the connecting line 367 and the tightening chamber 60 of the servo device 54 for the friction brake 50 resulting in the middle gear the supply line 252, 366 for the release chamber 62 can come. This supply line 252, 366 is then emptied via the connection line 158 of the manual valve 166, which is connected to this supply line via the connecting line 250, 254 passed through the 2, 3 switching valve 235.

This is achieved through its connection via the connecting line 154 to the one between the control collars 150 and 152 of the preload piston 146 formed differential area for w a higher production of the main pressure at lower The pressure control valve 370, which is decisive for driving speed, has a pressure control valve 370 which is displaceable in a valve bore 374 Valve body 372 with the control collars 376, 378 and 380. At the control collar 376 comes at the front that formed by the controller 100 as a function of the driving speed and via the line 234 brought up control pressure for application and still acts from the throttle pressure line 272 to the between the control collars 378 and 380 formed bo differential area against the introduced throttle pressure. The pressure prevailing in the connecting line 154 is therefore dependent on the ratio of these both, from the driving speed and from the ratio of these two, from the driving speed t> r> and influenced by the engine torque control pressures, in the by the control collar 380 of the valve body 372 an unpressurized outlet 382 is controlled, which is in the high position shown of the valve body 372 is blocked by the control collar 380. As soon as at higher driving speed the control pressure in the line 234 predominates, the valve body 372 is then in a lower position shifted, whereby the connected throttle pressure line 272 is then blocked by the control collar 378 and the connecting line 154 with the biasing piston 146 of the pressure regulating valve 104 with the unpressurized Outlet 382 of the pressure control valve 370 is connected.

That into the release chamber 62 of the servo device 54 for the middle gear resulting Friction brake 50 connected supply line 252, 366 built-in back pressure valve 388 includes a Valve body 390 with two control collars 392 and 394, which is displaceable in a valve bore 396 and is loaded by a precautionary spring 398. The force of this biasing spring 398 acts through the connecting line 198 of the manual valve 166 brought the main pressure against when the transmission is in reverse or is switched into a permanent shift of the slow gear, as a result of which the valve body 390 is pressed from the depicted lower position to a higher position. In the high position of its valve body is the backflow valve 388 ineffective, and it is on the other hand only for a dampening of the Tightening of the friction brake 50 resulting in the middle gear is effective as long as this connecting line 198 of the hand valve 166 is emptied. In the valve bore 396 of the backflow valve 388, a bushing 404 is also inserted, in which an auxiliary piston 402 is movable. The preloading spring 398 which loads the valve body 390 is supported on the bushing 404 which at the end joint with the auxiliary piston 402 via a connecting line 156 with the connecting line 154 is exposed to the pressure mentioned under certain driving conditions through the pressure control valve 370 is allocated.

The damping effect on the application of the friction brake 50 resulting in the middle gear of the back pressure valve 388 is based in the 1,2-upshift in the fact that in the then with the assistance of the 1,2-switching valve 203 taking place pressurization the supply line 232,367 connected to the tightening chamber 60 of the servo device 54 in the the release chamber 62 of the servo device 54 connected supply line 252, 366 an initial Back pressure is built up because then the connecting line 366 between the back pressure valve 388 and the release chamber 62 through the control collar 394 of the valve body 390 of the backflow valve 388 from the Connection line 252 with the 2,3-switching valve 235 is interrupted. The valve body 390 of the back pressure valve 388 is thus when the connecting line 198 is emptied by the biasing spring 398 in a with respect to the Supply line 252, 366 of the release chamber 62 pressed effective blocking position, the same as a Check valve 369 built into a bypass line of this supply line empties the Release chamber 62 prevented. Only when the back pressure in the connecting line 366 has a to Overcoming the force of the biasing spring 398 has reached a sufficient value, for example can be set to 0.7 at by means of a corresponding calibration of the preload spring 398, so will then by the difference between the two control collars 394 and 396 of the valve body 390 acting back pressure of the valve body 390

the depicted lower position pushed upwards, whereby the effective blocking position with respect to the supply line 252, 366 is canceled. The release chamber 62 can then be emptied via the 2, 3 switching valve 235 , because its supply line 252, 366 then contains a connection to the then pressureless connection line 158 of the manual valve 166 via the connecting line 250, 254. By the check valve 369 in one with respect to the back pressure valve 388 effectively by-pass pipe of the supply line 252, 366 of the release chamber 62 of the servo device 54 is disposed, a similar damping action upon release of the friction brake on the other hand, 50 is not achieved by the back pressure valve 388, because even then the The release chamber 62 is filled via the check valve 369 arranged in this bypass line. The release of the blocking position of the valve body 390 is also influenced by the pressure which is brought in via the line 156 and the distribution of which is controlled via the connection line 154 by the pressure control valve 370. It is thus possible to modify the application of the friction brake 50 in the 1.2 upshift compared to that in the 3.2 downshift, in which the backflow valve 388 also triggers such a damping effect when the friction brake 50 is applied. In the 3.2 downshift, with the assistance of the 2.3 switching valve 235, the supply line 252 'of the servo device for the friction clutch 36 resulting in the direct gear is emptied to the connecting line 158 of the manual valve 166 , while at the same time the tightening chamber 60 of the servo device 54 for the friction brake 50 resulting in the middle gear is distributed via the supply line 232, 367 main pressure and thereby the pressure oil contained in the release chamber 62 of this servo device 54 is displaced to build up a back pressure in the connecting line 366 with the back pressure valve 388 , which is only displaced after a certain height has been reached The valve body 390 is moved into its release position towards the connecting line 252 with the 2, 3 switching valve 235 . For the 3.2 downshift it can be provided, for example, that the valve body 390 of the backflow valve 388 is only moved into this release position at a back pressure of about 2 at, which then takes place with the assistance of the pressure control valve 370 by only then using the connecting line 154 , 156 the throttle throat dependent on the driving speed is allocated to supplement the force of the pretensioning spring 398 on the auxiliary piston 402 and the bushing 404 . The pressure control valve 370 can be set, for example, in such a way that it only supplies this additional control pressure to supplement the force of the pretensioning spring 398 to the backflow valve 388 when the vehicle is traveling at a low speed and at a higher engine torque, whereby the simultaneous pressurization of the control collars 150 and 52 of the Biasing piston 146 formed differential area a higher main pressure is achieved. This increase in the main pressure also contributes to the fact that the higher back pressure can be achieved in the 3.2 downshift in the connecting line 366 between the release chamber 62 of the servo device 54 and the back pressure valve 388.

As already mentioned above, the main pressure is also increased when the vehicle is pushing, in that a main pressure superimposed with the throttle pressure is then applied to the control collar 148 of the prestressing piston 146 for the prestressing spring 162 of the valve body 106 of the pressure regulating valve 104 via the connecting line 160 with the free-wheeling valve 406 comes. The free-wheeling valve 406 comprises a valve body 408 with control collars 410 and 412, which cooperate with corresponding control edges of the valve bore 418 . The valve body 408 is loaded by a pretensioning spring 414 , which counteracts the control pressure, which is dependent on the driving speed and which is brought up to act on the control collar 410 via the line 234 . If this control pressure outweighs the low throttle pressure in the connection line 272 of the free-wheeling valve 406 at high driving speed when the vehicle is pushing, then the valve body 408 is moved out of the illustrated high position for a through-connection of the main pressure from the main pressure line 164 , which is also connected to the free-wheeling valve 406 , to the Connection line 160 moved down.

In Fig. 4 shows a modified embodiment of the backflow valve 388 ' in that a connecting line 422 with the line 222 is provided to replace the connecting line 198 , which connects the throttle modulating valve 256 with the 1, 2 switching valve 203 . If, consequently, the throttle pressure in the connecting line 258 to the throttle modulating valve 256 has reached a size sufficient for modulation and a modulated throttle pressure is therefore delivered to the connecting line 422 , then the force of the pretensioning spring 398 is counteracted, whereby the valve body 390 is moved out of its blocking position with respect to the supply line 252 366 in which an emptying of the release chamber 62 dei servo device 54 for the friction brake 50 enabling the friction brake 50 enabling release order is shifted at a lower back pressure all when there is no modulated throttle pressure in this connecting line 422. D <the line 222 , bypassing the throttle modulating valve 256, is also connected to the connecting line 320 to the kick-down valve 308 , if this; Valve for a forced downshift of the gear <is actuated. In this embodiment, the backflow valve 388 ' ensures that the damping effect occurs when the friction brake 5 is applied when the kick-down valve 308 is used to forcefully change from the direct gear to the middle gear.

For this purpose 3 sheets of drawings

Claims (5)

Patent claims: 1. Hydraulic control device for an automatic Shifting motor vehicle change-speed gearbox with three forward gears, one of which is on one Gear change between a higher and a lower gear for the latter a friction brake is involved and this by means of a cylinder and a displaceable in this Servo piston existing servo device (54) is switchable, whose to a tightening chamber (60) and supply lines (232, 367; 252, 366) connected to a release chamber (62) through preferably on the engine torque and on the driving speed dependent switching valves (203,235) for a common pressurization of both chambers to release the friction brake (50) and for pressurization only the tightening chamber with simultaneous emptying the release chamber can be controlled to apply the friction brake, in which case the release chamber (62) of the servo device (54) connected supply line (252, 366) a spring-loaded Backflow valve (388; 388 ') is installed, the valve body (390) of the driving speed and the drive machine torque can be subjected to controllable control pressures, and wherein in a Bypass line of this supply line (252,366) a check valve (369) is installed, which only with activated filling of the release chamber (62) bypassing the backflow valve (388; 388 ') is opened, characterized in that that the servo device (54) is provided for the friction brake (50) resulting in the middle gear and the valve body (390) of the backflow valve (388; 388 ') by the spring (398) in a blocking position is biased, from which the valve body through which when the pressure is applied to the tightening chamber (60) of the servo device (54) in the Release chamber (62) of the servo device (54) connected to the supply line (252,366) building up Back pressure in a release position that enables the release chamber (62) to be emptied is moved. 2. Hydraulic control device according to claim 1, characterized in that the Backflow valve (388) is connected to an optionally pressurizable line (198) through which the valve body (390) of the backflow valve (388) can be loaded against the force of the spring (398) and in the release position can be moved. 3. Hydraulic control device according to claim 1, characterized in that the Backflow valve (388 ') a connection line (422,222, 258, 272) for a valve body (390) of the Force of the spring (398) counteracting pressure dependent on the drive engine torque is connected, this connection part being a throttle modulating valve designed as a pressure gradient valve (256) contains. 4. Hydraulic control device according to claim 3, characterized in that of the Pressure line (272, 258, 222) for the pressure dependent on the drive engine torque also one leading to a kick-down valve (308), through which a spring (318) displaceable valve body (310) except when the position exceeds the full throttle valve opening treatment blocked branch line is branched off, which when operated by the driver to one to the Switching valves (203, 235) leading, normally pressureless connecting line (320) can be controlled is, which also bypassing the throttle modulating valve (256) to the throttle modulating valve with the backflow valve (388 ') connecting section (422, 222) of the connecting line (422, 222, 258, 272) is connected. 5.1 hydraulic control device according to one of the Claims 1 to 4, characterized in that a further connection line is connected to the backflow valve (388; 388 ') (156, 154) for a valve body (390) supporting the force of the spring (398), depending on the driving speed feedable pressure is connected, this further connecting line has connection with a pressure control valve (370) included in the main pressure regulator circuit of the control device, which is the main pressure regulating control valve (104) of the control circuit at low driving speed controls for a higher production of the main pressure.