JPH037827B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a speed change control device for an automatic transmission for an automobile. [Prior Art] Conventionally, in an automatic transmission for a vehicle that includes a hydraulic torque converter and a gear transmission mechanism equipped with a plurality of frictional engagement devices for obtaining several gears, The operation of the frictional engagement device is automatically switched according to the operating state, and the gear transmission mechanism is automatically controlled to the most suitable speed-changing state for the operating state at that time. Switching control of such a frictional engagement device is normally performed by a hydraulic control device, and this hydraulic control device has control over the throttle pressure and vehicle speed, which change depending on the amount of depression of the accelerator pedal, that is, the opening degree of the intake throttle. A gear shift valve is incorporated in the gear shift valve, which is switched in accordance with the equilibrium relationship with the governor pressure, which changes accordingly. It is becoming more and more common to choose. Such hydraulic speed change control devices usually include a manual speed change valve that manually switches the speed range, and this allows the automatic transmission to change depending on the equilibrium relationship between the throttle pressure and the governor pressure as described above. The range in which the gear stage is changed, that is, the highest speed stage that can be changed is selected. The setting position of such an automatic transmission valve, that is, the switching range is as follows:
Normally, forward drive ranges such as D range, 2 range, and L range are prepared, and the variable speed valve is set to D.
When shifted into range, the automatic transmission is shifted from the first gear to the highest possible gear for the automatic transmission, typically a third or fourth gear. It's becoming like that. [Problems to be Solved by the Invention] The present invention aims to prevent engine overrun and improve high-speed driving performance in vehicles equipped with conventional automatic transmissions, and in order to prevent engine overrun and improve high-speed driving performance, the present invention aims to prevent third gear even in the fully open throttle range. It is an object of the present invention to provide a structure for mutually changing gears between the fourth gear and the fourth gear. For example, in the case of an automatic transmission that has four forward gears and the fourth gear is in overdrive, conventional hydraulic control devices can upshift from the third gear to the fourth gear and shift from the fourth gear to the fourth gear. As shown in Figure 1, the shift point for downshifting to third gear is determined only by the throttle opening, regardless of vehicle speed, in area A where the throttle opening is close to full throttle, and the gear is always in third gear. Ta. However, when the accelerator pedal is suddenly depressed during overdrive, the throttle opening increases rapidly, which causes the gear to be downshifted from the fourth gear to the third gear with a larger reduction ratio.
3 Engine overland occurs when a kickdown is performed, and high-speed driving performance deteriorates. In order to deal with this problem, it is desired that the gears be shifted between the third and fourth gears even when the throttle is fully open. In the conventional shift control device, the shift point between the third and fourth gears is set by the highest speed shift valve 3.
-4 This is done by setting the area of action of the throttle pressure and governor pressure that act on the valve element of the speed change valve, so that the throttle pressure and detent pressure operate the valve element against the governor pressure during kickdown. The governor pressure increases in roughly proportionate proportion to the vehicle speed at low and medium speeds, but reaches a plateau at high speeds due to oil leaks, etc., and as a result, the pressure between the third and fourth gears increases at high speeds. When trying to change gears, if the shifting points other than the area A in Figure 1 where the throttle opening is low are the same as before, in the area A where the throttle opening is high, it will be 3-4.
The governor pressure necessary for upshifting could not be obtained, and if a 3-4 upshift was made possible in the A region where the throttle opening is high, the shift point would be too low in the region where the throttle opening is low. Therefore, as already mentioned, the present invention has the advantage that in the region of high throttle opening when performing kickdown
The purpose of the present invention is to provide an improved shift control device for an automatic transmission that enables shifting between third and fourth gears as the vehicle speed changes, prevents engine overrun, and improves high-speed driving performance. It is something to do. [Means for Solving the Problems] In order to achieve the above-mentioned objects, the shift control device for an automatic transmission of the present invention includes a hydraulic pressure source, a pressure regulating valve that regulates the hydraulic pressure from the hydraulic source to line pressure, and a hydraulic pressure source. , a throttle valve that generates a throttle pressure that corresponds to the throttle opening, a governor valve that generates a governor pressure that corresponds to the vehicle speed, and a hydraulic servo of the gear transmission mechanism that is supplied according to the equilibrium relationship between the throttle pressure and the governor pressure. A shift control device for an automatic transmission, comprising: a plurality of shift valves that switch line pressure oil passages; and a detent valve that generates a detent pressure that operates the highest speed shift valve of the plurality of shift valves during kickdown. In this, the highest speed change valve includes a coast valve receiving the throttle pressure at one end, a valve body receiving the governor pressure at the other end, and a compression coil disposed between the coast valve and the valve body. a spring for supplying the detent pressure between the other end of the coast valve and one end of the valve body so as to partially offset the effect of the throttle pressure applied to the highest speed transmission valve; The throttle pressure and the governor pressure, which are partially offset, are opposed to each other. [Operations and Effects] In the shift control device of the present invention, by supplying detent pressure between the coast valve and the valve body when the accelerator pedal is strongly depressed, the throttle applied to the highest speed shift valve at this time is reduced. After a portion of the pressure is offset by the detent pressure, the throttle pressure and the governor pressure are made to oppose each other, and speed change control is performed by changing the governor pressure. By doing the above, in the region where the throttle opening is high, the speed change between the third and fourth gears is performed by opposing the governor pressure and the throttle pressure partially offset. For example, even if the accelerator pedal is strongly pressed while driving in overdrive, the variable gears can be changed according to the vehicle speed at that time. This improves high-speed driving performance and prevents engine overrun. In addition, in the speed change control device according to the present invention, the detent valve regulates the oil pressure that operates the highest speed change valve, that is, the detent pressure, so this oil pressure is stabilized and the highest speed change valve operates during high speed control. The stability of the operation will be ensured. Furthermore, when the manual gear shift valve is manually downshifted from D to 2 and D to L, the highest gear shift valve is restrained to the low speed side by line pressure regardless of the governor pressure, so high speed control is not possible. Regardless of the situation, manual downshifting is performed reliably, and high-speed control is possible only in the D range. [Example] The present invention will be described in detail below based on an example with reference to the accompanying drawings. FIG. 2 is a schematic diagram showing an example of an automatic transmission with an overdrive device, which has four forward speeds and one reverse speed, and the fourth forward speed is overdrive. This automatic transmission includes a torque converter 1, an overdrive mechanism 2, and a gear transmission mechanism 3 with three forward speeds and one reverse speed.
and is controlled by a hydraulic control device as shown in FIG. The torque converter 1 is well known and includes a pump 5, a turbine 6, and a stator 7. The pump 5 is connected to an engine crankshaft 8, and the turbine 6 is connected to a turbine shaft 9. The turbine shaft 9 constitutes the output shaft of the torque converter 1, which also serves as the input shaft of the overdrive mechanism 2, and is connected to a carrier 10 of a planetary gear system in the overdrive mechanism. A planetary pinion 14 rotatably supported by a carrier 10 meshes with a sun gear 11 and a ring gear 15. A multi-disc clutch 12 and a one-way clutch 13 are provided between the sun gear 11 and the carrier 10, and a multi-disc brake 19 is provided between the sun gear 11 and the overdrive case 16. A ring gear 15 of the overdrive mechanism 2 is connected to an input shaft 23 of the gear transmission mechanism 3. A multi-plate clutch 24 is provided between the input shaft 23 and the intermediate shaft 29.
A multi-plate clutch 25 is provided between the input shaft 23 and the sun gear shaft 30. A multi-plate clutch 26 is provided between the sun gear shaft 30 and the transmission case 18. The sun gear 32 provided on the sun gear shaft 30 is
A carrier 33, a planetary pinion 34 supported by the carrier, a ring gear 35 meshing with the planetary pinion, another carrier 36, a planetary pinion 37 supported by the carrier, and a ring gear meshing with the planetary pinion. Together with 38, it constitutes a two-row planetary gear mechanism. A ring gear 35 in one of the planetary gear mechanisms is connected to an intermediate shaft 29. Further, the carrier 33 in this planetary gear mechanism is connected to a ring gear 38 in the other planetary gear mechanism, and these carrier 33 and ring gear 38 are connected to an output shaft 39. Further, a multi-disc brake 27 and a one-way clutch 28 are provided between the carrier 36 and the transmission case 18 in the other planetary gear mechanism. In such a hydraulic automatic transmission with an overdrive device, each clutch and brake are engaged or released depending on the engine output and vehicle speed by a hydraulic control device, which will be explained in detail below. It is designed to perform four forward gear shifts including D) or one reverse gear shift by manual switching. Table 1 shows the transmission gear position and the operating status of the clutch and brake.

[Table] Here, ○ indicates that each clutch and brake are in an engaged state, and × indicates that they are in a released state. FIG. 3 is a hydraulic circuit diagram showing one embodiment of the present invention, which is a hydraulic control system for the automatic transmission shown in FIG. The oil sucked up by the oil pump 41 from the oil reservoir 40 is sent to a pressure regulating valve (line oil pressure control valve) 42 that controls line pressure, and the line pressure is regulated to a predetermined pressure in an oil passage 43.
Generate P _L. This line pressure P _L passes through the oil passage 43a to the variable speed change valve 44, and also to the oil passages 43b and 43.
Throttle valve 45 and detent valve 46 via c
is being supplied to. As is well known, the manual speed change valve 44 generally has parking (P), reverse (R), neutral (N),
It has switching positions such as D range (D), 2 range (2), L or 1 range (L or 1), and the line pressure P _L supplied to the input port 47 is at the switching position of the valve spool. Output port 48-51 depending
It is beginning to appear selectively in Table 2 shows the state in which hydraulic pressure appears at each output port at each switching position.

[Table] Throttle valve 45 is the amount of depression of the accelerator pedal,
That is, a hydraulic pressure that increases in accordance with the throttle opening is generated at the output port 52. The output port 48 of the manual speed change valve 44 is connected to the oil passage 48a.
The oil passage 48 leads to the clutch 24 (forward clutch) via the
b communicates with the input port 54 of the governor valve 53. The governor valve 53 regulates the line pressure P _L supplied to its input port 54 in accordance with the vehicle speed, and generates a governor pressure Pgo in its input port 55 in accordance with the vehicle speed. The detent valve 46 regulates the supplied line pressure P _L and outputs the detent pressure from the output port 99 through the oil passage 99a to port 1 of the throttle valve 45.
It is designed to output to 01. The detent pressure generated in the oil passage 99a is caused by the movement of the kick-down valve 102 of the throttle valve 45, when the amount of depression of the accelerator pedal is large and the throttle opening is in the fully open range, and the kick-down valve 102 is pushed upward in the figure. In response to the communication between the input port 101 and the output port 100 of the throttle valve 45, the oil passages 100a, 100b, 100c, 10
0d, it is supplied to an overdrive control valve 58, which is a 1-2 speed change valve 56, a 2-3 speed change valve 57, and a 3-4 speed change valve, which will be described later. In addition, when the throttle opening is outside the fully open range, the throttle valve 4
Since the kickdown valve 102 of No. 5 closes the detent pressure input port 101, the oil passage 100a is
Hydraulic pressure supply to etc. will be stopped. The 1-2 speed change valve 56 has two valve bodies 60 and 61 facing each other in the axial direction via a compression coil spring 59.
Contains. The valve body 60 is formed by the sum of the downward pressing force in the figure, which is applied by the spring 59, and the downward pressing force in the figure, which is applied by the throttle pressure Pth applied to the port 62 via the oil passage 52a, as shown in the figure. Due to the balance with the upward pressing force in the figure given by the governor pressure Pgo applied to the lower end port 63 via the oil passage 55a, the position is displaced downward as shown by the reference numeral 56A in the figure, and the position shown by the reference numeral in the figure 56B
The switch can be switched between upwardly displaced positions as shown in . Another valve body 61 is
The line pressure P _L that appears at the output port 50 of the manual speed change valve 44 when it is switched to the L range is regulated and supplied to the ports 64 and 65 via the low modulator valve 66, thereby shifting the line pressure downward in the figure. The valve body 60 is forcibly held in the above-mentioned switching position 56A. Similarly, the 2-3 conversion valve 57 also has a compression coil spring 67.
Valve bodies 68 and 69 facing each other in the axial direction via
The valve body 68 has the sum of the downward pressing force in the figure similarly applied by the spring 67 and the downward pressing force due to the throttle pressure Pth exerted on the port 70 via the oil passage 52b, and the oil passage. 55b to the lower end port 71 in the figure.
Due to the equilibrium relationship with the upward pressing force exerted by Pgo in the figure, there is a shift between the downward switching position indicated by reference numeral 57A in the figure and the upward switching position indicated by reference numeral 57B in the figure. It is now possible to switch. In addition, on the upper surface of the upper valve body 69, when the manual speed change valve 44 is switched to the 2nd range, the line pressure P _L appearing at the output port 49 is shown in the oil passages 49a and 49.
9b and 72, and at this time, the valve body 69 is displaced downward in the figure, and the valve body 68 is forcibly held in the downward switching position shown at 57A. People are starting to do this. In this embodiment, the 3-4 converter 58 is an overdrive control valve, i.e., a maximum speed change valve.
is a compression coil spring 73 and a third coast valve 9
It has a valve body 74 and a piston 75 that face each other in the axial direction via a valve body 8, and governor pressure Pgo supplied to a port 76 through an oil path 55c is applied to the lower end (other end) of the valve body 74. It's becoming like that. Further, an oil passage 52 is provided at the upper end (one end) of the third coast valve 98.
Throttle pressure Pth is supplied through port 77 and port 77. The port 78 corresponding to the upper end (one end) of the piston 75 receives the line pressure that appears at the output port 49 when the manual speed change valve 44 is switched to the L range or the 2 range through oil passages 49a, 49c,
It is supplied via the shuttle valve 79 and the oil passage 49d, or the oil passage 43d, the shuttle valve 49, and the oil passage 4.
9d, the line pressure, or a hydraulic pressure substantially lower than the line pressure in the manner described below, is supplied. When the hydraulic pressure acting on the port 78 is substantially reduced from the line pressure as described above, the piston 75
In this state, the valve body 74 is in a position where it is pushed upward in the figure by the action of 3, and in this state, the throttle pressure Pth acts on its upper end from the port 77 via the third coast valve 98, and the throttle pressure Pth acts on its lower end from the port 76. Depending on the equilibrium relationship between the governor pressure Pgo and the governor pressure Pgo, switching is performed between the switching positions 58A and 58B in the figure. The 3-4 conversion valve 58 further has a detent pressure input port 103, and detent pressure is applied to the input port 103 when the throttle opening is approximately fully open. This detent pressure is supplied between the third coast valve 98 and the valve body 74, so that the third coast valve 98 receives the throttle pressure Pth from above in the figure and the detent pressure Pd from the bottom in the figure. The valve body 74 receives detent pressure Pd from above in the figure, and receives governor pressure Pgo from below in the figure. At this time, by appropriately setting the area of the end facing each pressure of the third coast valve 98 and the valve body 74, the effect of the throttle pressure Pth is partially canceled out, and the governor pressure Pgo is reduced by the throttle pressure whose effect is reduced. Equilibrium relationship with pressure Pth (in this case, the throttle opening is almost fully open, so the throttle pressure Pth is constant, and the detent pressure Pd is also regulated constant, so the change in its value is due to (Only the governor pressure Pgo.)
This allows the oil passage to be switched. However, as will be described later, when line pressure P _L acts on port 78, line pressure P _L is substantially higher than throttle pressure Pth, so piston 75 is forcibly pushed downward in the figure, and accordingly, valve The body 74 is forcibly switched and held at the switching position 58A in the figure, regardless of the governor pressure Pgo acting on its lower end. The oil passage 48b is connected to the port 80 of the 1-2 speed change valve 56.
When the variable speed change valve 44 is switched to the D range, the line pressure P _L is supplied. This line pressure P _L is applied from the port 81 to the oil passage 48 when the 1-2 speed change valve is in the upward switching position indicated by 56B.
c and is led to port 82 of 2-3 speed change valve 57. The line pressure P _L led to this port 82 is 2
-3 When the speed change valve 57 is in the downward switching position indicated by reference numeral 57A in the figure, the oil passage 4 is opened from the port 83.
8d and is led to the brake 26 (second brake). In addition, the 2-3 speed change valve 57 is 57B in the diagram.
When in the upward switching position as shown in , the hydraulic pressure supplied to the port 82 is guided to the port 84, passes through the oil passage 48e to the shuttle valve 85, and from there passes through the oil passage 48f to the clutch 25.
(reverse clutch). Note that when the variable speed change valve 44 is switched to the L range, the line pressure appearing at its output port 50
P _L is applied to the ports 64 and 65 of the 1-2 speed change valve 56 via the low modulator valve 66, thereby pushing down the valve body 61, and then from the port 86 via the oil path 86a to the brake 27 (fur It is supplied to the inside side of the brake (strivers brake) and engages the brake. When the manual speed change valve 44 is switched to the reverse range, the hydraulic pressure appearing at the output port 51 of the variable speed change valve 44 on the outside side of the brake 27 is transferred to the oil path 5.
1a, 1-2 transmission valve 56 through ports 87, 88 and oil passage 88a, thereby engaging the clutch. The line pressure _P
is supplied. When the 3-4 speed change valve 58 is in the downward switching position as shown by reference numeral 58A in the figure, the line pressure P _L supplied to the port 89 is transferred to the overdrive mechanism 2 through the port 90 and the oil passage 43e. to the clutch 12, and when the 3-4 transmission valve 58 is in the upwardly switched position as shown at 58B in the figure.
It is supplied to the brake 19 of the overdrive mechanism 2 via the port 91 and the oil path 43f. A throttle 92 is provided in the middle of the oil passage 43d, and a drain port 94 whose opening/closing is controlled by a valve body 93 is further provided in the oil passage at a position downstream from the throttle. . The valve body 93 is adapted to be actuated by a solenoid device 95. In this case, the valve body 93 is always pressed to a position that closes the drain port 94 by a spring not shown in the figure, and is pulled upward in the figure only when the solenoid 95 is energized.
It is designed to open 4. Solenoid 95 is controlled by an electrical circuit as shown. In this electric circuit, 96 is a power source, which may be a battery mounted on the vehicle. Further, 97 is a switch for turning on/off the energizing circuit of the solenoid, and this is a manual switch that is selectively operated according to the driver's will. When the manual switch 97 is open, the solenoid device 95 is not energized and the valve body 93 is in the position where the drain port 94 is closed as shown. On the other hand, when the manual switch 97 is closed, the solenoid device 95 is energized, and the valve body 93 is pulled upward in the figure by the solenoid device to open the drain port 94. Manual switch 9
7 is selectively activated according to the driver's will, as described above. It may be configured to be closed at other times, or vice versa, as the case may be. Furthermore, as is clear from the operation mode described later, for example, the manual switch 97
When the switch 97 is configured as a toggle switch toggled between two operating positions indicating on or off of the overdrive device, the switch 97 is closed when the switch is switched to the on position which activates the overdrive device. , switch 97 is configured to open when switched to an off position that inhibits operation of the overdrive device. Next, the operation of the hydraulic control device shown in FIG. 3 will be explained.

[D range]

When the manual speed change valve 44 is switched to the D range, line pressure appears only at the port 48, and this line pressure is directly supplied to the clutch 24. When the vehicle is stopped or running at low speed, the governor pressure generated by the governor valve 53 is low, and generally the 1-2 transmission valve 56, 2-3 transmission valve 57, and 3
-4 speed change valves 58 are respectively numbered 56A and 5 in the figure.
7A and 58A, and the hydraulic pressure supplied through the oil passage 48b is at the port 8.
0, and therefore, hydraulic pressure is not supplied to the reverse clutch 25 and second brake 26, which are connected to the oil passages thereafter. Also, at this time, port 8 of the 3-4 speed change valve 58 is connected to the oil passage 43g.
The hydraulic pressure led to 9 is supplied to overdrive mechanism 2 clutch 12. Therefore, in this state,
The overdrive mechanism 2 is in a locked (directly connected) state, and the gear transmission mechanism 3 is in a first gear state. In a general operating mode, as the vehicle speed gradually increases from this state, the governor oil pressure gradually increases, and accordingly, at a certain vehicle speed, the 1-2 speed change valve 56 is switched to the position 56B in the figure. , the line pressure is led to the port 81, and this oil pressure is transmitted from the port 82 of the 2-3 speed change valve 57 to the port 83, and the oil passage 4
It comes to be supplied to the second brake 26 through 8d. In this state, the gear transmission mechanism 3 is switched to the second speed state. When the vehicle speed further increases, the 2-3 speed change valve 57 is also switched to the position 57B in the figure due to an increase in the governor oil pressure. As a result, the hydraulic pressure supplied to the port 82 is now transmitted to the port 84, and is thereby supplied to the reverse clutch 25 via the oil passage 48e. In this state, the gear transmission mechanism 3 is switched to the third gear state. As the vehicle speed further increases, the 3-4 transmission valve 58 is also switched to the position 58B in the figure, whereby the hydraulic pressure supplied to the port 89 is transferred to the port 91.
will be supplied to In this state, the overdrive mechanism 2 operates and an overdrive state is achieved. The above has explained the change in switching that occurs as the governor pressure increases due to an increase in vehicle speed, but of course, such change in switching is based on the balance between the governor pressure and the throttle pressure that act in opposition to the valve element of each switching valve, as described above. The switching point changes depending not only on the vehicle speed but also on the amount of depression of the accelerator pedal. Conversely, when the vehicle speed decreases,
The 3-4 speed change valve 58, the 2-3 speed change valve 57, and the 1-2 speed change valve 56 are shown in the order of 5 from 58B in the figure.
To 8A, from 57B to 57A, from 56B to 56A
, and a change in the gear position pressed occurs. The accelerator pedal was suddenly depressed, and oil line 100a
When detent pressure is generated in the 1-2 speed change valve 56 via the oil passage 100b, if the car is running in the second gear.
The valve body 60 is pushed downward as shown in the figure by the detent pressure supplied to the 2nd gear via the oil passage 100c, and the valve body 60 is shifted down to the first gear.
The valve body 68 is moved downward in the figure by the detent pressure supplied to the -3 speed change valve 57 and shifted down to the second speed. When the accelerator pedal is depressed until the throttle valve is fully open while driving in overdrive, the daytent pressure is
d to the input port 103 of the 3-4 speed change valve 58
is guided to push up the third coast valve 98 from below to offset a portion of the throttle pressure applied from the third coast valve 98 from above. The effects of the detent pressure, throttle pressure, and governor pressure at this time are as follows. Check the values of throttle pressure, detent pressure, and governor pressure.
Let them be Pth, Pd, and Pgo. The area of the end of the third coast valve 98 facing the throttle pressure is Ath, the area of the end facing the detent pressure is Ad, and the valve body 74
The area of the end facing the detent pressure at Bd,
Let Bgo be the area of the end facing the governor pressure. Therefore, the valve body 74 is directed downward to Bd, Pd+Ath, Pth-Ad,
Receives the power of Pd. Therefore, the governor pressure is Ath・Pth−
(Ad−Bd)・Opposes the force of Pd. Since Ad>Bd can be set, Ath・Pth>Ath・Pth−(Ad−Bd)・Pd, and the throttle pressure is partially offset. on the other hand,
Governor pressure acts on the valve body with Bgo and Pgo forces, so by setting the area so that Ath, Pth- (Ad-Bd), PdBgo, Pgo when the throttle is fully open, the governor pressure Shift control is achieved. With the above configuration, the valve body 7
4 is now operated mainly by detent pressure and governor pressure applied from below, and the shift point between the third and fourth gears is set in the fully open throttle range A, as shown in Figure 4. In this case, it is determined only by changes in governor pressure, regardless of throttle opening.

[2 range] When the manual gear shift valve 44 is switched to the 2 range,
In addition to the port 48, oil pressure also appears in the port 49, and the oil pressure that appears in the port 49 is supplied to the port 72 of the 2-3 speed change valve 57 via the oil passages 49a and 49b, and is also supplied to the shuttle valve from the oil passage 49c. 7
9. Overdrive control valve 58 via oil passage 49d
port 78 to force these valves in the downwardly switched position shown at 57A and 58A in the figure. Therefore, in such a state, the overdrive mechanism 2 is reliably held in a locked state, and the gear transmission mechanism 3 is
operates only in second gear.

[L range]

When the manual speed change valve 44 is switched to the L range,
Furthermore, oil pressure also appears at the output port 50, and this oil pressure acts on ports 64 and 65 of the 1-2 speed change valve 56 through the low modulator valve 66, and the valve is shifted downwardly as shown at 56A in the figure. Forced to hold in position. In this state, the gear transmission mechanism 3 is maintained at the first speed. As described above, in the speed change control device of the present invention, detent pressure is supplied between the coast valve and the valve body provided in the highest speed change valve (3-4 speed change valve), and part of the action of the throttle pressure is In other words, by reducing its effect and making the governor pressure and its throttle pressure oppose each other, even in the region of high throttle opening, the third gear and third gear shift in accordance with changes in vehicle speed. Shifts are now performed between four gears, improving high-speed driving performance and preventing engine overrun. Furthermore, since the detent valve adjusts the oil pressure for operating the maximum speed transmission valve, this oil pressure is stabilized, and the stability of the operation of the maximum speed transmission valve during high speed control is ensured. Furthermore, by manually downshifting the manual transmission valve from D to 2 and from D to L, the highest speed transmission valve is constrained to the low speed side by line pressure regardless of the governor pressure, so that high speed Manual downshifting is performed reliably regardless of control, and high-speed control is possible only in the D range.

[Brief explanation of drawings]

Fig. 1 is a graph showing a shift line between the third and fourth gears in a conventional hydraulic control system, Fig. 2 is a skeleton diagram of an automatic transmission, and Fig. 3 is a shift control according to the present invention. A hydraulic circuit diagram showing one embodiment of the device, and FIG. 4 is a graph showing a shift line between the third gear and the fourth gear in the shift control device of the present invention. 40... Oil server, 41... Oil pump, 42... Pressure regulating valve, 44... Manual speed change valve, 45
... Throttle valve, 46 ... Detent valve, 53
...Governor valve, 56...1-2 speed change valve, 57...
2-3 speed change valve, 58...3-4 speed change valve (overdrive control valve), 73...compression coil spring, 74
... Valve body, 75 ... Piston, 98 ... Third coast valve.

Claims (1)

[Claims] 1 A hydraulic source, a pressure regulating valve that regulates the hydraulic pressure from the hydraulic source to line pressure, a throttle valve that generates a throttle pressure that corresponds to the throttle opening, a governor valve that generates a governor pressure that corresponds to the vehicle speed, and the throttle pressure. a plurality of shift valves that switch oil passages for line pressure supplied to the hydraulic servo of the gear transmission mechanism according to an equilibrium relationship between the pressure and the governor pressure; and a highest speed shift valve among the plurality of shift valves at the time of kickdown. In a control device for an automatic transmission equipped with a detent valve that generates a detent pressure for operating the maximum speed change valve, the highest speed change valve has a coast valve that receives the throttle pressure at one end, and a valve body that receives the governor pressure at the other end. and a compression coil spring disposed between the coast valve and the valve body, and transmits the detent pressure to the highest speed transmission valve between the other end of the coast valve and one end of the valve body. Shift control for an automatic transmission, characterized in that the throttle pressure is supplied so as to partially offset the effect of the applied throttle pressure, and the partially offset throttle pressure and the governor pressure are made to oppose each other. Device.