FR2549783A1 - Assembly forming immobilisation clutch control valve - Google Patents

Abstract

The invention relates to an assembly forming an immobilisation clutch control valve. According to the invention, it comprises an immobilisation valve 801 for controlling the engagement of an immobilisation clutch and an immobilisation synchronisation valve 802 for controlling the supply of a first pressurised fluid to the immobilisation valve; the first pressurised fluid acts on the immobilisation valve in order to engage the clutch; the synchronisation valve moves in order to stop the pressure feed of actuating oil towards the immobilisation valve when the second oil pressure increases beyond a first predetermined value in order to allow the immobilisation valve to pass to a first position to free the engagement of the immobilisation clutch; the immobilisation valve passes from its first position to its second position in order to reengage the clutch when the second oil pressure increases above a second predetermined value greater than the first. The invention applies especially to the motor vehicle industry.

Description

 The present invention relates to controls for clutching immobilizations, and more particularly to corrugated valve assemblies for effecting automatic engagement of the immobilizing clutch.

 In an automatic transmission having a torque converter with an immobilizing clutch, it is necessary to engage the immobilizing clutch at each of the high speed feed transmission ratios, such as a second to the second gear ratio. high, for a greater operational efficiency of the automatic transmission. However, a significant shock occurs at the change if the change is made while the immobilizer clutch is kept engaged.

In order to eliminate the presence of the shock of change, electronic controls have been proposed which temporarily release the engagement of the immobilizer clutch during a change between reports in the transmission. However; such electronic controls require expensive hardware including an electronic control unit, sensors and actuation means.

 The present invention relates to a simple and inexpensive order of immobilization for a multi-speed automatic transmission having an immobilization clutch which requires less installation space.

 The present invention provides a control that includes a movable immobilization valve at first and second positions to control the disengagement and engagement of the immobilizer clutch, and a movable immobilization delay valve for stopping power. in a first fluid under pressure to the immobilization valve. The first pressurized fluid urges the immobilizing valve to the second position to engage the immobilization clutch. The immobilizing valve and the immobilizing delay valve are movable in response to a second fluid pressure. The immobilization time valve is moved to the position to stop the supply of first fluid pressure when the second pressure is applied. of fluid increases beyond a first predetermined value, allowing the immobilizing valve to move to its first position to release engagement of the immobilizing clutch. The immobilizing valve is returned from its first position to its second position to re-engage the immobilization clutch when the oil pressure of the second signal increases beyond a second predetermined value which is greater than the first predetermined value.

 A preferred form of control is adapted to maintain the immobilizing clutch in a condition at the lowest gear or first gear ratio, in the transmission, to produce the application of increased torque through the transmission, this gear ratio. For this purpose, a bias signal oil pressure source is an oil chamber in the transmission, which is maintained under pressure when each of the forward speed ratios except the first, is set in the transmission. .

 Preferably, the control is adapted to maintain the immobilization clutch in a condition released for a longer time at a wider opening degree of throttling. To accomplish this function, a valve drum or shut-off valve has a pressure action zone that is always pressurized with respect to the throttling. In the present case, the term "throttle-related pressure" indicates a throttling pressure, a throttling modulator pressure and a line pressure that are variable while the throttling opening varies.

 Preferably, the control is adapted to maintain the immobilization clutch in a condition relieved at low rotational speeds of the engine to prevent the presence of vibrations which would otherwise occur with the immobilization clutch maintained under engaged condition at low engine speeds. For this purpose, a first shutoff valve interrupts the supply of the second pressurized fluid to the immobilizer valve and the shut-off valve or shut-off valve when a pressure to the regulator is lower than that of the shut-off valve. a predetermined value and a second shutoff valve interrupts the supply of fluid at the first pressure to the shut-off valve or shut-off valve when the total of the pressure at the regulator and at least one lower fluid pressure is lower than a predetermined value.

The invention will be better understood, and other objects, features, details and advantages thereof will appear more clearly in the following explanatory description made with reference to the accompanying schematic drawings given solely by way of example illustrating several embodiments of the invention and in which
FIG. 1 is a schematic view of a drive train of a four-speed automatic transmission;
FIGS. 2 (a), 2 (b) and 2 (c), when combined, show a circuit diagram of a hydraulic pressure control system of the automatic transmission coupled to an immobilisation control according to the invention. 'invention;
FIG. 3 is a schematic view of the immobilization control illustrated in a black block in FIG. 2 (a); and
FIG. 4 is a schematic view of a second embodiment of an immobilization control according to the present invention.
Referring to FIG. 1, the drive train of a four-speed automatic transmission having four feed rate ratios including overdrive is described. The power transmission mechanism comprises an input shaft I to which a rotational power is applied by an output shaft E of a motor, by a torque converter T / C; an output shaft 0 which transmits the motive power to a final drive; a first group of planet gears G1; a second group of planetary gears
G2; a first clutch C1; a second clutch C2; a third clutch C3; a first brake B1; a second brake B2; and a one-way clutch OWC.The first planetary gear group G1 comprises a sun gear SI, an inner ring R1, a support PCI carrying pinions PI engaged simultaneously with the two gears SI and Ri, while the group D planetary gears C2 comprises a sun gear S2, an inner ring R2 and a support PC2 carrying pinions P2 engaged simultaneously with the two gears S2 and R2.

The PCI support can be connected between the clutch CI to the input shaft I and the sun gear S1 can be connected by the clutch CI to the input shaft I. The PCI support can be connected by the clutch C3 to the inner ring R2, too. The sun gear S2 is constantly connected to the input shaft I, and the inner ring R1 and the support PC2 are constantly connected to 11 output shaft 0. The brake B1 is adapted to anchor the sun gear S1. The brake B2 is a belt brake which is actuated in response to the oil pressure applied to its servo application chamber S / A and to the servo release chamber S / R having a relatively large operating area of pressure. Indeed, when the oil pressure is brought to the servo application chamber S / A, the brake B2 is applied and when the oil pressure is supplied to the servo release chamber S / R , the brake B2 is released whether the oil pressure is supplied to the servo application chamber S- / A or not.

The one-way clutch OWC is constructed to allow direct rotation (ie the same rotation as that of the output shaft of the engine E) but to prevent reverse rotation (ie ie the rotation opposite to the direct rotation) (that is, it acts as a brake only during the reverse rotation).

The T / C torque converter comprises a PI pump movable wheel, a turbine wheel T, a stator ST and an immobilization clutch L. The pump movable wheel PI is connected by a torque converter cover PI 'to the motor output shaft E. The turbine wheel T is connected to the input shaft I and and the stator ST is connected by a one-way clutch SGWC to a stationary part.

The immobilization clutch L connected to the turbine wheel T is axially movable and cooperates with the cover PI 'of the torque converter which is integral with the pump moving wheel PI to form a clutch oil chamber LC. immobilization and is pressed against the torque converter cover PI 'to rotate with it when the oil pressure in the LC chamber becomes lower than that in the torque converter T / C. The construction details of the immobilization clutch L can be found in US Patent No. 4,305,487 published December 15, 1981.

The clutches CI, C2 and C3, and the brake B1, the one-way clutch Os ™ and the brake B2 can come into engagement in the predetermined combinations shown by the following table to produce the four feed ratios and a ratio of reverse.

<tb><SEP> CI <SEP> C2 <SEP> C3 <SEP> 31 <SEP> B1 <SEP> Report <SEP> I <SEP> = <SEP> 0.45
<tb><SEP> trans
<SEP> (oc) <SEP> of <SEP> 2 <SEP> = <SEP> 0.45
<tb><SEP> I <SEP> mission
<tb><SEP> mission
<tb> First <SEP> o <SEP> o <SEP> I <SEP> +0 (2 <SEP> 3.22
<tb><SEP> 0 (2
<tb><SEP> o
<tb> Second <SEP> where <SEP> o (i <SEP> + q2 <SEP> 1.38
<tb><SEP> oL
<tb><SEP> I
<tb><SEP> o
<tb> Fourth <SEP> o <SEP>'<SEP> ~ <SEP> 0.69
<tb><SEP> o <SEP> | <SEP> 1 <SEP> +0 (1
<tb><SEP> ffi <SEP> ~ SEP> ~~ <SEP> .. <SEP>. <SEP>.
<tb> March
<tb> backward <SEP> o <SEP> o <SEP>, <SEP> - <SEP> 1 <SEP> - <SEP> 2.22
<Tb>

 On the board, the sign "o" indicates for each of the clutches and brakes, that the clutch or brake in question is engaged or applied. The characters 0 (1 and 0 (2 denote the ratio of the number of teeth of the inner ring RI to the number of teeth of the corresponding sun gear S1 as well as the ratio of the number of teeth of the inner ring R2 to the number of teeth of the sun gear The transmission ratio is a ratio of the number of revolutions of the input shaft I relative to the output shaft 0. The mark (OWC) below the brake B1 means that the report of first gear is produced by engagement of the one-way clutch OWC even if the brake B1 is not applied, however in this first gear ratio it is not possible for the output shaft 0 to drive the motor by the power train (ie there is no motor braking) .The "o" sign in the column below B2 indicates that the application chamber S / A servo-control and / or the S / R servo-release chamber in question receives oil under pressure.

 Referring to Figures 2 (a), 2 (b) and 2 (c), a hydraulic pressure control system for the four-speed automatic transmission will be briefly described.

 In FIGS. 2 (a), 2 (b) and 2 (c), the immobilizing clutch oil chamber LC, the torque converter T / C, the clutches C1, C2, C5, the brakes B1 and B2 and the S / A pump application chamber and the S / R servo release chamber are schematically illustrated.The hydraulic control system comprises an oil pump o / P, an overdrive inhibitor switch SW, a line pressure regulating valve 2, a manual selector 4, a throttling valve 6, a fail-safe throttling valve 8, a throttle modulator 10, a pressure modifier 12, a return valve 14, a line relief valve 16, a regulating valve 18, a change valve 1-2, a change valve 2-3, a change valve 3-4, a synchronization valve 2-4, a valve synchronization valve 28, 2-3, a synchronization valve 3-4, a synchronization valve 32, a gearbox 34 first pressure range, a torque converter pressure reducer 36, a pressure accumulator 38, an accumulator 40 of 4-3, and a solenoid 42 overdrive inhibitor. Reference numerals 402, 404, 406, 408, 409, 410, 411, 412, 414, 416, 418, 429, 422, 424, 426, 428, 4six, 432, 434, 436, 438, 440, 442, 444, 446, 448 and 450 designate oil lines, numbers 502, 504, 506 and 508 of the selector valves and numbers 602, 604, 606, 608, 610, 612, 614, 616, 618, 620, 622 624, 626, 628, 630, 650, 652, 654, 656 and 658 of the orifices and the numbers 750, 752, 754, 756, and 758 of the valves.

 Referring to the table, the S / A servo application chamber is held under pressure during each of the feedrate ratios except for the lowest or first gear and the servo release chamber S / R is pressurized at an intermediate gear ratio, such as the third, between the highest or fourth ratio or the lowest or first gear. It may be noted that the oil pressure supplied to the servo application chamber S / A through the oil line 432 of the change valve 1-2 is employed by a valve or control valve assembly 60. as a first fluid pressure signal. Set 60 uses the oil pressure supplied to the servo release chamber S / R through the oil line 444 as the second pressure signal of the fluid. fluid. These first and second signals are transferred by the oil flow 856 opening into the conduit 432 and an oil conduit 855 opening into the oil conduit 444, respectively.

Referring to Figure 3, the assembly 60 will be described. The control valve assembly 60 includes a valve or shut-off valve 801 and an immobilization timing or timing valve 802. The valve 801 comprises a drum 812 which is slidably disposed in a bore 811, a spring 813 urging the drum 812 from one end of the bore 811 and an end plug 814 closing the other end of the bore 811. The bore 811 has a number of orifices 811a, 811b, 811c, 8114, 811e, 811f and 811g.The orifices 811a and 811c are purge orifices. Port 811b receives PTH throttle pressure through an oil line 851 connected to oil line 420 where a fluid pressure proportional to the throttle opening degree is produced by throttle valve 6. L 811d is connected to the LC chamber of the immobilizing clutch by an oil line 852. The orifice 811e receives a supply pressure of the PTC torque converter via an oil line 853 connected to the air duct. supply oil from the torque converter 450.As when the immobilization oil chamber LC receives this pressure
PTC, the immobilization clutch L is disengaged, this pressure can be referred to as the immobilization release signal. "The orifice 811f is connected by an oil conduit 854 to an orifice 821c of the immobilization synchronization valve. 802. The orifice 811g is colrmected by an oil conduit 855 to an orifice 821e of the immobilization synchronization valve and also to the servo release chamber S / R.

The drum 812 has flat portions 812a, 812bu 812c and 812d (the flat portions 812b and 812c are flat portions of the same diameter, the flat portions 812a and 812d have a smaller diameter than the diameter of each of the flat portions 812t and 812c ). The oil pressure in the orifice 81 lob acts on a surface difference between the flat portions 812a and 812b.According to the position of the drum 812, the flat portions 812b and 812e allow the orifice 811d to communicate with the orifice 811c or 811e orifice. The oil pressure in the orifice 811f acts on a surface difference between the flat portions 812e and 812d. The oil pressure in the orifice 811g acts through an orifice 814a of the plug 814 on the end face of the flat portion 812d fitting into a bore formed in the plug 814.

 The immobilization synchronization valve 802 comprises a drum 822 slidably disposed in a bore or bore 821, and a spring 823 urging the drum 822 to the right, looking at FIG.

Drill 821 has orifices 821 and 821b, 821c, 821d and 821e. The orifices 821a and 821b are drain ports, the orifice 821c is connected to the aforementioned oil conduit 854, the orifice 821d is connected by an oil conduit 856 to the servo application chamber S / A and the orifice 821e is connected to the aforementioned oil conduit 855. The drum 8-2 has flat portions 822a and 822b of the same diameter and the flat portions 822a and 822b allow the orifice 821c to communicate with the orifice 821b or orifice 821d according to the position of the drum 822.The oil pressure in the orifice 821e acts on the right end, looking at FIG. 3, of the flat part 822b.

 The operation will be described below.

 To effect a change of the first to second gear ratio, the changeover valve of 1-2 of Fig. 2 (b) moves from a position illustrated by its right half to a position illustrated by its left half, putting the oil conduit 412 in communication with the oil conduit 432, thereby to provide pressurized oil to the servo application chamber S / A. This oil pressure is delivered through oil line 856 to port 821d of immobilization timing valve 802.

As, in this condition, when no oil pressure acts on the end of the flat portion 822b through the orifice 821e, the drum 822 of the immobilization timing valve is in a first position illustrated by its half 821d can communicate with the orifice 821c. Thus, the oil pressure in the conduit 856 enters the oil conduit 854 and reaches the orifice 811f of the immobilization valve 801. The oil in the orifice 811f acts on the surface difference between the flat portions 812c and 812d, biasing the drum 812 to the left, looking in FIG. 3, overcoming the spring 813, at a position illustrated by its lower half. By taking the position at the lower half, the oil pressure in the LC oil chamber is discharged past oil line 852 and port 81 through the drain port 811c.

As a result, the immobilizing clutch L is engaged.

In this situation, the speed of the vehicle increases and the pressure of the PG regulator increases correspondingly, the change valve 2-3 of FIG. 2 (b) moves from the position illustrated by its right half, looking at FIG. 2 (b) at a position shown by its left half looking at FIG. 2 (b), to put the oil line 432 in communication with the oil line 434, to provide the pressurized oil to the servo release chamber S / R. Thus, the oil pressure in the S / R depressurizing chamber begins to increase. This oil pressure is delivered from the oil line 855 to port 811g of the immobilizing valve 801 and also to 821e of the immobilization synchronization valve 802. The spring 823 of the synchronization valve 802 is selected so that it deforms at a lower force than the force with which the spring 813 of the valve 801 begins. to deform. Thus, the immobilization synchronization valve 802 moves from the position illustrated by its lower half by looking at FIG. 3 at the position illustrated by its upper half by looking at FIG. 3 at a stage where the oil pressure supplied to the chamber S / R servo release is still low. This forces the oil conduit 854 which has received the oil pressure of the conduit 856 to communicate with the bleed port. Thus, the biasing oil pressure acting on the surface difference between the flat portions 812c and 812d escapes and disappears, allowing the spring 813 to push the drum 812 back to the position illustrated by its upper half oil 852 in communication with the oil conduit 853. This results in the application of the torque converter PTC pressure to the immobilizer clutch chamber LC to disengage the clutch L. While the operation of changing the ratio of second to third gear progresses and that the oil pressure in the servo release chamber S / R continues to increase, the oil pressure increases to a sufficiently high value to press the drum 812 to the left looking at FIG. 3, overcoming the spring 813.Following, the valve 801 is brought back from the position illustrated by its upper half to the position illustrated by its lower half on the fi FIG. 3, putting the oil conduit 812 in communication with the bleed port 811c, thereby releasing oil from the immobilizing clutch oil chamber LC to thereby engage the immobilizer clutch L. The adjustment is such that it ensures that the engagement of the clutch L will take place after increasing the oil pressure in the servo release chamber
S / R at a value high enough to establish the third gear, that is, after the end of the change of the second gear to the gear ratio.

 In the above manner, the engagement of the immobilizing clutch L is released temporarily during a short period of time, during the passage of the second to the third ratio.

When the regulator pressure PG increases further to a sufficiently high value to shift the change valve 24 from 3-4 of FIG. 2 (b) from the position illustrated by its right half to a position illustrated by its left half in FIG. In Figure 2 (b), the oil pressure in the S / R servo release chamber starts to escape. When the oil pressure in the S / R chamber falls slightly, the valve 801 moves from the position shown by its lower half by looking at FIG. 3 at the position illustrated by its upper half by looking at FIG. 3, thanks to the action of the spring 813, applying the supply pressure of the PTC torque converter to the oil chamber LC of the ignition clutch, thereby freeing the engagement of the immobilizing clutch L. Or the oil pressure in the servo release chamber
As S / R continues to fall, the timing valve 802 moves from the position shown by its upper half by looking at FIG. 3 at the position shown by its lower half, looking at FIG. 3 graced by the action of the spring 823, putting the oil pressure in the servo application chamber S / A in communication with the oil conduit 854 to act on the end of the immobilizing valve 801, thereby returning the valve 801 to the position illustrated by its lower half against the spring 813. As a result, the immobilizing clutch
L is again engaged. When the oil pressure in the S / R servo release chamber drops to a sufficiently low value to allow movement of the immobilization timing varix 802 to the position illustrated by its half lower, the change of the ratio of third to the fourth ratio is accomplished. In the above manner, the engagement of the immobilizing clutch L is temporarily released for a short period of time when making a change of the ratio of third to fourth gear.

 In a similar manner, the engagement of the immobilizing clutch L is released temporarily during a change from the fourth to the third and during a change from the third to the second.

On reading the above description, it will be understood that in the embodiment illustrated in FIG. 3, although the traction clutch L is maintained in the engaged condition of second, third and fourth speed, the energy of the shock of change is absorbed by the fluid connection between the pump movable wheel PI and the turbine wheel T which is temporarily established by releasing engagement of the mobilization clutch LC during a change between two of the second, third and fourth ratios
It will be understood that the duration during which the immobilizing clutch is released during a change operation is the difference between the time at which the immobilization timing changes position and the time at which the immobilization valve 801 changes from position. This difference may advantageously be varied in response to the degree of throttling opening of the engine because the time required for the change operation increases as the degree of throttling opening increases. For this purpose, the throttling pressure is introduced at the orifice 811b of the immobilization valve 801. With the introduction of the throttling pressure, the more it increases, the more the oil pressure in the orifice 811g at which the immobilizing valve 801 changes position increases. Indeed, the higher the throttling pressure, the higher the oil pressure in the servo release chamber S / R must be high to change the immobilizer valve 801. Therefore, while the throttling pressure As the rate at which the immobilizing valve changes is increased, the rate at which the immobilization clutch L is released during a change between two gears is increased. Thus, the immobilization clutch can no longer be reengaged before the end of the change operation with significant adjustments to the throttle opening.

 Although the valve assembly ~ or control valve 60 has been explained as being coupled to the hydraulic control system which allows four speed ratios, it can be coupled to a hydraulic control system as disclosed in US Patent No. 4 324 156 published April 13, 1982 where, in FIG. 2A, the counterparts to the servo application chamber, the servo release chamber and the seventh release pressure transfer duct are designated by FIGS. reference numerals 76, 76 'and 382 respectively.

 Referring to Fig. 4, a second embodiment of a control valve assembly will now be described which is now designated by reference numeral 60 '.

 This embodiment is different from the first in that a first shutoff valve 803 and a second shutoff valve 804 are provided. The first and second shutoff valves 803 and 804 are provided to prevent the engagement of the immobilizing clutch L in the operating ranges at low speeds of rotation of the engine.

 The first speed shutoff valve 803 comprises a drum 832 slidably disposed in a bore 831 of the valve and a spring 833 urging the drum 832 to the left looking at FIG. 4.

Drill 831 has orifices 83a, 831b, 831c, 8d and 831e. The orifices 831b and 831e are purge ports, the orifice 831a receives the regulator pressure PG of an oil conduit 857, the orifice 831c is connected to an oil conduit 855 and the orifice 831d is connected by an oil line 858 to a S / R control chamber. The drum 832 has flat portions 832a and 832b of the same diameter and the flat portions 832a and 832b allow the port 831c to communicate with the orifice 831b or the orifice 831d according to the position of the drum 832. port 83Ia acts on the left end looking at Figure 4, the flat portion 832a.

 The second shutoff valve 804 comprises a drum 842 slidably disposed in a valve bore 841 and a spring 843 urging the barrel 842 to the left looking at Fig. 4. The bore 841 has orifices 841a, 841b 841c, 841d, 841e and 841f.

The orifices 841c and 841f are purge orifices, the orifice 841a is connected to the oil duct 857, the orifice 841b is connected by an oil duct 859 to the aforementioned clutch C3, the orifice 841d is connected to a fuel line 856 and port 841e is connected by oil line 860 to the servo application chamber S / A. Drum 842 has flat portions 842b and 842c of the same diameter and a flat portion of reduced diameter 842a. The flat portions 842a and 842c allow the orifice 841d to communicate with the orifice 841c or the orifice 841e according to the position of the drum 842.

The oil pressure in the orifice 841a acts on the left end looking at FIG. 4, of the flat portion 842a and the oil pressure in the orifice 841a acts on a surface difference between the flat portions 842a and 842b .

 The operation of this embodiment is as follows.

 During the first or second gear operation, the drum 842 of the second speed shutoff valve 804 is subjected to a right-handed force resulting from the pressure at the regulator acting on the flat portion 842a and another directed force. to the right resulting from the oil pressure in the clutch C3 acting on the surface difference between the flat portions 842a and 842b, and as long as the total of these forces directed to the right is lower than the force of the spring 843 , the second speed shutoff valve 804 remains in the position shown by its upper half by looking at Fig. 4 where the oil pressure of the servo application chamber S / A is blocked by the flat portion 842c. since no pressure accumulates in the oil conduit 854 regardless of the state of the immobilizer synchronization valve 802, the immobilization clutch L can not be engaged. However, when the total of the forces directed to the right becomes larger than the force of the spring 843, the oil line 860 can communicate with the oil line 856 (this state is the same as the hydraulic pressure circuit of the 3), put the immobilizing valve 801 and immobilization synchronization valve 802 in the operating state of the case of FIG. 3. If the force of the spring 843 is well established, the engagement of the clutch The immobilization L is prevented even at transmission changes at the second gear as long as the vehicle speed remains lower than a predetermined value. As the aforementioned forces are the result of the addition of the force of the regulator pressure PG and the force resulting from the line pressure which is supplied as the actuating pressure to the clutch C3, if the line pressure increases (that is, if the degree of throttle opening increases), the total of the forces directed to the right reaches the predetermined value while the pressure of the regulator PG is still low, while that if the line pressure decreases (that is, if the degree of throttling opening decreases), the total forces towards: E right does not reach the predetermined value until the pressure regulator reaches the higher value. This. means that if the throttle opening degree is small even if the regulator pressure PQ becomes excessively high, the total of the right-handed forces can not overcome the force of the spring 843 because the line pressure is low, leaving thus the clutch dtimmobi- lisation L in unobstructed condition even after passing the transmission to the second gear.

 The first speed shutoff valve 803 serves to prevent the engagement of the immobilizer clutch L as long as the speed of the vehicle is lower than a predetermined value. In fact, when the PG regulator pressure acting in the 831a mode is low, the first speed shutoff valve 803 is in a position halfway down where the oil pressure of the servo release chamber S / R is blocked by the flat portion 832b.When the regulator pressure PG becomes greater than a predetermined value, the first speed shutoff valve 803 moves to the position illustrated by the upper half by looking at Fig. 4. In this state the oil line 858 can communicate with an oil line 855 (the same state as the hydraulic pressure circuit of FIG. 3), the immobilization valve 801 and the immobilization synchronization valve operate in the same manner. as described above. Thus, as long as the vehicle speed is lower than the predetermined value, engagement of the clutch L is prevented even at the transmission changes to the third gear. The predetermined speed value of the vehicle at which the first valve of 803 speed change of position is greater than a change speed value where the transmission changes from the second to third gear ratio at low throttle opening degrees, and this means that during operation at low degrees With the throttling opening, the engagement of the immobilizing clutch L is only possible after the speed of the vehicle has increased beyond the above predetermined value of the vehicle speed after changing the speed of the vehicle. transmission for the third report.

 The immobilizer clutch L is not engaged even if the transmission has changed to the fourth gear as long as the vehicle speed is lower than a predetermined speed. As during operation with a four-speed ratio, the oil pressure in the clutch C3 is discharged and the force acting on the second speed shutoff valve 804 to the right is the force due to the pressure of the clutch. Only controller PG, the second speed shutoff valve 804 does not change position relative to that illustrated at its upper half to the position shown at its lower half until the PG pressure of the regulator increases excessively. . In this situation, the speed of the vehicle at which the shutoff valve 804 changes from the illustrated position to a half greater than the position illustrated by its lower half is set to a higher value than a vehicle changeover speed at which the Transmission passes from the second report to the third report. When the second speed shutoff valve 804 is in the position shown by its upper half, as the oil pressure of the servo application chamber S / A is blocked by the flat portion 842c and thus does not reach the duct S56 oil, the clutch L is clear.Therefore, even if the transmission changes to the fourth gear, the engagement of the immobilizer clutch L is prevented at vehicle speeds below the predetermined speed of the vehicle as long as the degree of throttling is small.

 In the manner described above, the engagement of the immobilizer clutch L is prevented at slow vehicle speed ranges with the second, third or fourth gear ratios, which leaves the pump moving impeller T / C torque converter in fluid connection with the turbine wheel T, thereby preventing the presence of an unpleasant engine vibration that would otherwise occur at low vehicle speeds.

 In the control valve assemblies described above, the throttling pressure is employed as a fluid pressure signal and is introduced into the oil conduit 851, but the same effect can be obtained even if a pressure of the throttle modulator which is produced by the throttle modulator valve 10 of Fig. 2 (a) or a line pressure produced by the line pressure regulator valve 2 of Fig. 2 (b) is used instead of state pressure. thus, the term "throttle-related pressure" is used to indicate the throttle pressure, the throttle modulator pressure, and the line pressure, which is a more accurate description of the throttling pressure character. Throttling modulator pressure and line pressure can be found in US Patent No. 4,324,156, and in particular the description referring to Figure 3 of this patent.In this US patent, the term "pressure Strangulation modulator "corresponds to the term" throttling modulator pressure "used in the present application.

 It will now be appreciated that the present invention provides an immobilizing control valve assembly which maintains the immobilization clutch engaged in each of the advance ratios with the exception of the weakest ratio because the engagement of the immobilizer clutch is released temporarily during a shift between two gear ratios, thereby improving the operating efficiency of the automatic transmission. In the case of the embodiment described for FIG. 4, since the engagement of the immobilizer clutch at the low speeds at each of the ratios is prevented, the presence of unpleasant vibrations derived from the operation of the engine at low speeds is prevented. .

Claims (6)

R E V E N D T C A T T O N S  1.- Colrmaslde for an immobilization clutch for a tiarlsrr, automatic ission of an engine having a number of gear ratios comprising a lowest gear ratio and a highest gear ratio, characterized in that she understands  first means producing a fluid pressure to produce a first fluid pressure when each of said speed ratios except for the lowest is set in the transmission;  second means producing a fluid pressure for producing a second fluid pressure when a predetermined ratio of speed between the highest and the lowest ratio is set in the transmission;  an immobilizing control valve (801) actively connected to the immobilizing clutch and movable to first and second positions to control the disengagement and engagement of the immobilization clutch respectively, said valve comprising a first surface pressure actuator adapted to communicate with the first fluid pressure producing means, and a pressure acting surface in fluid communication with said second means producing a fluid pressure to be biased to its second position;  an immobilization synchronization valve (802) actively connected between the first fluid pressure producing means and the immobilizing valve and movable at a first position to communicate the first fluid pressure to the first pressure acting surface so as to urging the immobilizing valve means to its second position and at a second position to cause the biasing pressure acting on the first pressure action surface to be exhausted, said Eobilization timing valve means including a a pressure acting surface in fluid communication with the second means producing a fluid pressure and biased by the second fluid pressure to its second position;  first resistive means (823) for resisting movement of the immobilization synchronization valve to its second position until the second fluid pressure increases above a first predetermined value; and  second resistive means (813) for resisting movement of the immobilizing valve to its second position until the second fluid pressure increases beyond a second predetermined value, said second predetermined value being greater than the first.  2.- control according to claim 1, characterized in that the second aforesaid resistive means comprises a spring biasing the immobilizing valve to its first position and means for providing an oressionen relation to the constriction to said immobilization valve so urging said immobilization valve to its first position.  3.- control according to claim 2, characterized in that the first aforementioned resistive means comprises a spring biasing the immobilization synchronization valve to its first position.  4.- control according to claim 1, characterized in that it further comprises:  regulating means for producing a regulating fluid pressure;  a first rate shutoff valve (803) actively connected between the second fluid pressure means and the immobilization synchronization valve and movable to a first position to interrupt the communication of the first signal fluid pressure to said valve immobilization synchronization circuit and a second position for putting said signal fluid pressure tap in communication with said immobilization schlocking valve, said first speed shutoff valve having a communication surface in communication of fluid with the regulator fluid pressure for biasing to its second position; and  a second rate cutoff valve (804) actively connected between the first fluid pressure producing means and the immobilization timing valve and movable at a first position to stop communication of the first signal fluid pressure with the valve immobilization synchronization circuit and a second position for communicating the first fluid pressure with the immobilization valve, said second shut-off valve comprising a pressure acting surface in fluid communication with the regulating means for biasing to the second position.  5. Control according to claim 4, characterized in that it further comprises a third means producing a fluid pressure to produce a third fluid pressure when the highest gear ratio is not established dates the transmission, and in that the second rate shutoff valve comprises a second pressure acting surface in fluid communication with the third signal fluid pressure for biasing to its second position.  6. Control according to claim 5, characterized in that it further comprises a spring which resists the movement of the speed cutoff valve to its second position until the pressure of the regulator fluid increases beyond a third predetermined value and a spring which resists the movement of the second rate cutoff valve to its second position until the total bias force causes a pressure of the regulator fluid and said third fluid pressure increases beyond a fourth predetermined value.