JPH052863B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an automatic transmission, and particularly to an automatic transmission, which is configured to obtain a plurality of gears by combining the operating positions of a plurality of shift valves, and is equipped with a constant speed traveling device that maintains a vehicle speed at a set vehicle speed. The present invention relates to a shift control device for an automatic transmission. (Prior Art) Automatic transmissions generally installed in automobiles combine a torque converter and a speed change gear mechanism, and the power transmission path of this speed change gear mechanism is controlled by selectively operating multiple friction engagement elements such as clutches and brakes. It is configured to automatically shift to a predetermined gear position by switching the gear position (for example, see Japanese Patent Laid-Open No. 183160/1983). On the other hand, automobiles equipped with this type of automatic transmission are sometimes equipped with a constant speed traveling device that maintains the vehicle speed at a set vehicle speed. This constant speed traveling device automatically opens and closes the engine throttle valve using an actuator according to the difference between the vehicle speed set by the driver and the actual vehicle speed, thereby converging the actual vehicle speed to the set vehicle speed. However, with this constant speed traveling device, there are cases where it is not possible to converge the vehicle speed to the set vehicle speed simply by controlling the throttle opening, and in such cases, the automatic transmission is A signal is output to the control device to automatically shift the gear to a gear that matches the set vehicle speed (see, for example, Japanese Patent Laid-Open No. 117010/1983). (Problems to be Solved by the Invention) By the way, automatic transmissions have a problem of so-called shift shock when changing gears. In order to reduce this shift shock, it is effective to delay the engagement of the friction engagement element for engine braking that is engaged in the next gear after the friction engagement element that was engaged in the previous gear begins to release. However, if this is done, when the gear shift is a downshift when the engine brake is activated at a particularly high vehicle speed, the so-called "downshift" occurs between the time when the gear shift to the lower gear is delayed and the engine brake starts to operate. A state of idle running occurs,
This will cause discomfort to the passengers. To solve this problem, when downshifting at or above a predetermined speed, the engine brake friction engagement element is engaged from the high gear, and then the engine brake friction engagement element is engaged, and then the gear is switched to a low gear. By not passing through such a state during a downshift, the shift shock can be effectively reduced in low vehicle speed ranges where engine braking is not particularly required, and at the same time, engine braking can be applied quickly during the shift in high vehicle speed ranges. Conceivable. However, in this case, the following problems occur in an automatic transmission equipped with a constant speed traveling device. In other words, when driving at a constant speed and climbing a hill, when the throttle opening is increased to a predetermined limit in order to cope with the drop in vehicle speed, and the transmission is then downshifted, this downshift is for acceleration. Nevertheless, if the vehicle speed at that time is higher than the predetermined vehicle speed, the frictional engagement element for engine braking operation will be engaged during gear shifting, and therefore the frictional engagement element will be engaged at the beginning of shifting during acceleration. This causes a large shift shock. The present invention addresses the above-mentioned problems in automatic transmissions, and in particular, in automatic transmissions equipped with a constant speed traveling device, the present invention appropriately controls frictional engagement elements for engine braking during downshifts during constant speed traveling. By doing this, when this downshift is for accelerating when going uphill, etc., unnecessary early activation of the engine brake is avoided and the shift shock is reduced, and when the above downshifting is when going downhill, etc. When the vehicle is decelerating, the purpose is to activate the engine brake early to prevent a free-wheeling state, thereby ensuring that a good gear shift state can be obtained in any case. (Means for Solving the Problems) That is, the speed change control device for an automatic transmission equipped with a constant speed traveling device according to the present invention operates on the actuator of the friction engagement element that switches the power transmission path of the speed change gear mechanism. In a device that is equipped with a plurality of shift valves for supplying and discharging oil, and a plurality of gears are obtained by a combination pattern of the operating positions of these shift valves, engine braking is performed from a predetermined high gear from the constant speed traveling device. When outputting a downshift signal to a predetermined low gear position on which the gearbox is applied, an acceleration/deceleration determining means determines whether the downshift is an acceleration one or a deceleration one; The combination pattern of the operating positions of is switched from a high gear position pattern to a low gear position pattern via a pattern that does not engage the friction engagement element for engine braking, and when downshifting during deceleration, the above pattern is changed. Similarly, a control means is provided for switching from a pattern for a high gear position to a pattern for a low gear position via a pattern for engaging the friction engagement element for engine braking. (Function) According to the above configuration, when the transmission is downshifted to accelerate the vehicle speed to the set vehicle speed, such as when climbing a slope while driving at a constant speed, the friction engagement element for engine braking is engaged from a high gear position. Since the gear is switched to the lower gear through a state in which the gear is not engaged, a large shift shock due to engagement of the frictional engagement element at the beginning of the shift during acceleration can be prevented. In addition, when the transmission is downshifted to reduce the vehicle speed to the set vehicle speed, such as when descending a slope while driving at a constant speed, the engine brake friction engagement element is engaged from a high gear. Since the pattern of the low gear stage is switched, the friction engagement element is engaged at the beginning of the gear shift, and the engine brake is quickly activated, thereby avoiding the idle running state of the vehicle. (Example) Examples of the present invention will be described below. First, the mechanical configuration of the automatic transmission according to this embodiment will be explained with reference to FIG.
The main component is the torque converter 2.
0, a speed change gear mechanism 30 driven by the output of the converter 20, a plurality of friction engagement elements 41 to 46 such as clutches and brakes that switch the power transmission path of the mechanism 30, and a one-way clutch 51,
52, and these ranges D, 2, 1, and R as running ranges, and 1 to 1 in the D range.
4 speed, 1 to 3 speed in 2 range, 1 to 3 in 1 range
It is now possible to obtain two speeds. The torque converter 20 includes a pump 22 fixedly installed in a case 21 connected to the engine output shaft 1, and a turbine 23 disposed opposite to the pump 22 and driven by the pump 22 via hydraulic oil. , a stator 25 that is interposed between the pump 22 and the turbine 23 and supported by the transmission case 11 via a one-way clutch 24 to increase torque;
3 and directly connects the engine output shaft 1 and the turbine 23 via the case 21. The rotation of the turbine 23 is outputted to the transmission gear mechanism 30 via the turbine shaft 27. Here, a pump shaft 12 passing through a turbine shaft 27 is connected to the engine output shaft 1, and the shaft 12 drives an oil pump 13 provided at the rear end of the transmission. On the other hand, the speed change gear mechanism 30 is constituted by a Ravigneaux-type planetary gear device, and includes a small sun gear 31 with a small diameter that is loosely fitted on the turbine shaft 27, and a small sun gear 31 that is loosely fitted on the turbine shaft 27 behind the sun gear 31. a large sun gear 32 with a large diameter; and a plurality of short pinion gears 33 meshed with the small sun gear 31.
, a long pinion gear 34 whose front half meshes with the short pinion gear 33 and whose rear half meshes with the large sun gear 32; the long pinion gear 34 and the short pinion gear 33;
A ring gear 36 is meshed with the front half of a long pinion gear 34. A forward clutch 41 and a first one-way clutch 51 are interposed in series between the turbine shaft 27 and the small sun gear 31, and a coast clutch 42 is interposed in parallel with these clutches 41 and 51. In addition, there are three
A -4 clutch 43 is interposed, and a reverse clutch 44 is further interposed between the turbine shaft 27 and the large sun gear 32. Further, a 2-4 brake 45 made of a band brake for fixing the large sun gear 32 is provided between the large sun gear 32 and the reverse clutch 44, and a 2-4 brake 45 is provided between the carrier 35 and the transmission case 11. , a second receiving the reaction force of the carrier 35.
A one-way clutch 52 and a low reverse brake 46 for fixing the carrier 35 are provided in parallel. The ring gear 36 is connected to the output gear 14, and rotation is transmitted from the output gear 14 to left and right wheels (not shown) via a differential gear. Next, the frictional engagement elements 41 to 46 such as the above-mentioned clutches and brakes, and the one-way clutches 51 and 5
To explain the relationship between the operating state of No. 2 and the gear stage, first, in the first speed, the forward clutch 41 is engaged and the first and second one-way clutches 51,
52 becomes locked. Therefore, the output rotation of the torque converter 20 is transmitted from the turbine shaft 27 to the planetary gear device 30 via the forward clutch 41 and the first one-way clutch 51.
It is input to the small sun gear 31 of. In this case, since the carrier 35 is fixed by the action of the second one-way clutch 52, the planetary gear device 3
0 operates as a fixed gear train that does not perform differential operation that transmits rotation from the small sun gear 31 to the ring gear 36 via the short pinion gear 33 and long pinion gear 34. As a result, the small sun gear 31 and ring gear 36
A first speed state with a large reduction ratio corresponding to the diameter ratio of Next, in 2nd speed, in addition to the above-mentioned 1st speed state, the 2-4 brake 45 is activated, the large sun gear 32 in the planetary gear device 30 is fixed, and the second one-way clutch 52 is placed in an idle state. . Therefore, the rotation transmitted from the turbine shaft 27 to the small sun gear 31 is transmitted to the long pinion gear 34 via the short pinion gear 33, and the long pinion gear 34 is connected to the large sun gear 3 that meshes with the long pinion gear 34.
2 is fixed, it revolves on the large sun gear 32, and the carrier 35 rotates accordingly.
As a result, the rotation of the ring gear 36 is increased by the rotation amount of the carrier 35 (revolution of the long pinion gear 34) compared to the first speed state, and a second speed state is obtained in which the reduction ratio is smaller than that at the first speed. Furthermore, in 3rd gear, the 2-4 brake 45 is released from the 2nd gear state, and the 3-4 brake 45 is released from the 2nd gear state.
Clutch 43 is engaged. Therefore, the rotation of the turbine shaft 27 is simultaneously input to the small sun gear 31 via the forward clutch 41 and the first one-way clutch 51, and at the same time
It is also input to the carrier 35 via the 4 clutch 43. As a result, the entire planetary gear device 30 rotates integrally, and a third speed state is obtained in which the ring gear 36 rotates at the same speed as the turbine shaft 27. Furthermore, in the fourth gear, the 2-4 brake 45, which was once released in the third gear, is re-engaged. Therefore, the rotation of the turbine shaft 27 is input from the 3-4 clutch 43 to the carrier 35 of the planetary gear device 30, and the long pinion gear 34 is revolved.
Since the large sun gear 32 with the gear 4 meshed therewith is fixed by the 2-4 brake 45, the long pinion gear 34 rotates while revolving together with the carrier 35. As a result, the ring gear 36 that meshes with the long pinion gear 34 is rotated at an increased speed by the rotation of the carrier 35 (rotation of the turbine shaft 27) by the amount of rotation of the long pinion gear 34, which causes the ring gear 36 to rotate in the overdrive state. You can get speed. In this case, the forward clutch 41 is in the engaged state, but
Since the first one-way clutch 51 in series with this rotates idly, the rotation of the turbine shaft 27 is not input to the small sun gear 31. Furthermore, at reverse speed, the reverse clutch 4
4 and the low reverse brake 46 are engaged, and the rotation of the turbine shaft 27 is input to the large sun gear 32 of the planetary gear device 30.
The carrier 35 of the gear device 30 is fixed. Therefore, rotation is transmitted through a fixed gear train from the large sun gear 32 to the ring gear 36 via the long pinion gear 34, and the reduction ratio corresponds to the ratio of the diameters of the large sun gear 34 and the ring gear 36. is obtained, but in that case, the rotation direction of the ring gear 36 is the same as that of the turbine shaft 2.
7 or the rotation direction of the large sun gear 32. Note that the first one-way clutch 51, which transmits rotation in 1st to 3rd gears, and the second one-way clutch 52, which receives reaction force in 1st gear, idle during coasting, so engine braking does not operate in these gears. But 3 in D range
speed, 2nd and 3rd speeds in 2 ranges, and 1st and 2nd in 1st range
In the D range, the coast clutch 42 is engaged in parallel with the first one-way clutch 51, and in the first gear of the first range, the low reverse brake 46 is engaged in parallel with the second one-way clutch 52. Engine braking is obtained in 2nd and 3rd gears of the range and 1st and 2nd gears of the 1st range. Table 1 summarizes the relationship between the operation of each of the hydraulic engagement elements 41 to 46 and the one-way clutches 51 and 52 and the gear position.

【table】

[Table] *Coasting space-time rotation Next, according to FIG.
Hydraulic actuator 41a that operates 46 respectively.
Hydraulic circuit 60 for supplying and discharging hydraulic oil to ~46a
I will explain about it. Here, among the above-mentioned hydraulic actuators 41a to 46a, 2-4 brake 45
The hydraulic actuator 45a is connected to the apply port 4.
5a' and a release port 45a'', and when hydraulic oil is supplied only to the apply port 45a', the 2-4 brake 45
At the same time, when both ports 45a' and 45a'' are not supplied with hydraulic oil, and both ports 45
When hydraulic oil is supplied to both a′ and 45a″, 2
-4 brake 45 is released. In addition, other actuators 41a to 44
a, 46a are constituted by ordinary hydraulic pistons, and are adapted to engage the frictional engagement element when hydraulic oil is supplied. This hydraulic circuit 60 includes a regulator valve 61 that adjusts the pressure of hydraulic oil discharged from the oil pump 13 to the main line 100 to a predetermined line pressure as shown in FIG. A throttle valve 62 is provided to generate a throttle pressure. This throttle pressure is then applied to the throttle modulator valve 6.
3 and then supplied to the regulator valve 61, whereby the line pressure is set to a value corresponding to the accelerator opening of the engine. The hydraulic circuit 60 also includes a manual valve 64 that selectively sends the line pressure to each hydraulic line according to the selected range, and a manual valve 64 that operates according to the gear position to transfer the line pressure to each of the hydraulic actuators 41a to 41a. 1- selectively supplied to 46a
2, 2-3, 3-4 shift valves 71, 7
2,73 are provided. The manual valve 64 is connected to the main line 1
an input port f into which line pressure is introduced from 00;
The movement of the spool 64a causes the input port f to become the first and second output ports a and b in the D range, and the first and second output ports in the 2 range. , for the third output ports a, b, and c, the first, third, and fourth output ports a,
c and d, and in the R range, to the fifth output port e. First to fifth output lines 101 to 105 are connected to each output port a to e, respectively. Further, the 1-2, 2-3, 3-4 shift valves 71, 72, 73 have spools 71a, 7, respectively.
2a, 73a are biased to the right side in the drawing by springs, and control ports 71b, 72b, 73b are provided on the right side of these spools. A first control line 106 branched from the main line 100 is connected to the control port 71b of the 1-2 shift valve 71.
Second and third control lines 107 and 108 branched from the first output line 101 are connected to b, respectively, and these control lines 106 and
107 and 108 are provided with first, second and third solenoid valves 76, 77 and 78, respectively. These solenoid valves 76 to 78 are
When each of the shift valves is OFF, control pressure is introduced into the control ports 71b to 73b of the shift valve to position the spools 71a to 73a on the left side in the drawing, and when each is ON, the control pressure is introduced into the control ports 71b to 73b. Drain the spools 71a to 73a
is positioned on the right side. Here, these solenoid valves 76 to 78
is turned on and off according to the gear position to be set by signals A, B, and C from a control circuit 200 that receives the vehicle speed and engine throttle opening from sensors 201 and 202, respectively. However, the ON/OFF combination patterns of the solenoid valves 76 to 78 at each gear stage of the travel range are basically set as shown in Table 2.

[Table] On the other hand, among the first to fifth output lines 101 to 105 connected to each output port a to e in the manual valve 64, those connected to the main line 100 in each forward range of D, 2, and 1 are connected to the main line 100. The first output line 101 is connected to the actuator 4 of the forward clutch 41 via a one-way orifice 80.
Guided by 1a. Therefore, the forward clutch 41 is always engaged in the D, 2, 1 range. Note that the first output line 101 has an N-D line for buffering when the forward clutch is engaged.
An accumulator 81 is provided. Further, a line 111 is branched from this first output line 101 to the above-mentioned 1-2 shift valve 71.
This branch line 111
When the first solenoid valve 76 is turned on and the spool 71a moves to the right, the servo piston 45 is activated via the one-way orifice 82.
The servo apply line 112 is connected to the apply port 45a' of a. Therefore, D,2,1
When the first solenoid valve 76 is ON in the range, that is, in 2nd, 3rd, and 4th speeds in the D range, 2nd and 3rd speeds in the 2nd range, and 2nd speed in the 1st range, the servo apply pressure is applied to the apply port 45a'. will be introduced. In addition, the above servo apply line 112
A 1-2 accumulator 83 is also provided as a buffer when the servo piston (2-4 brake) is engaged. Further, the second output line 102 communicating with the main line 100 in the D and 2 ranges is led to a 2-3 shift valve 72. When the second solenoid valve 77 is OFF and the spool 72a is located on the left side, the line 102 is communicated with the 3-4 clutch line 113 that reaches the actuator 43a of the 3-4 clutch 43 through the one-way orifice 84. Therefore, when the second solenoid valve 77 is OFF in the D and 2 ranges, that is, the 3-4 clutch 43 is engaged in the 3rd and 4th speeds of the D range and the 3rd speed of the 2 range. In addition, above 3
-4 clutch line 113 has a bypass valve 85 and 2-3 parallel to one-way orifice 84.
A timing valve 86 is provided to adjust the engagement timing of the 3-4 clutch 43, and a 2-3 accumulator 87 is also provided on the 3-4 clutch line 113 for buffering when the 3-4 clutch is engaged. is provided. Further, a line 114 branched from the 3-4 clutch line 113 and the first output line 1
A line 115 branched from 01 is led to the 3-4 shift valve 73. Then, when the third solenoid valve 78 is OFF and the spool 73a is located on the left side, the 3-4 clutch line 113
A line 114 branched from the servo release line 1 connects to the release port 45a'' of the servo piston 45a via the one-way orifice 88.
16 and a line 115 branched from the first output line 101 is connected to the actuator 4 of the coast clutch 42 via a one-way orifice 89.
The clutch lines 117 and 2a are connected to coast clutch lines 117, respectively. Therefore, in the D,2 range, the second and third
When both solenoid valves 77 and 78 are OFF,
That is, in the 3rd speed of the D range and the 3rd speed of the 2nd range, servo release pressure is introduced into the release port 45a'' of the servo piston 45a to release the 2-4 brake 45, and in the D, 2, 1 range, the 3rd solenoid When valve 78 is OFF, that is, 3rd gear in D range,
The coast clutch 42 is engaged in the 2nd and 3rd speeds of the 2nd range and the 1st and 2nd speeds of the 1st range. Here, the 3-4 clutch line 113 and
The line 114 branched from the line 113
A 3-2 timing valve 90 and a 3-2 capacity valve 91 are provided between the 3-4 clutch pressure and the servo release pressure through branch lines 118 and 119, respectively. ing. Further, the coast line 117 is provided with a bypass line 120 that bypasses the one-way orifice 89, and is provided with a 3-4 capacity valve 92 that opens and closes the line 120. This valve 92 is the above-mentioned 3-4
When clutch pressure is generated and the manual valve 64 is selected to the 2nd range or 1st range, the third output line 103 is connected to the main line 10.
When the bypass line 12 is connected to
0 is opened to adjust the discharge timing of the coast clutch pressure. In addition, the above 3rd
A line 121 branched from the output line 103 is led to the pressure increasing side of the regulator valve 61 via a throttle back-up valve 93, and the line pressure is increased in the 2nd range and the 1st range. Further, the fourth output line 104, which is communicated with the main line 100 in one range by the manual valve 64, is led to the 1-2 shift valve 71 via the low reuse valve 94 and the line 122. Then, when the first solenoid valve 76 is OFF and the spool 71a is located on the left side, the line 122 communicates with the low reverse brake line 123 that leads to the actuator 46a of the low reverse brake 46 via the one-way orifice 95 and the shuttle valve 96. be done. Therefore,
When the first solenoid valve 76 is OFF in the 1st range, that is, in the 1st gear of the 1st range, the low reverse brake 46 is engaged. Further, a fifth output line 105 that communicates with the main line 100 in the R range communicates with the low reverse brake line 123 via the one-way orifice 97 and the shuttle valve 96, and also connects with the one-way orifice from the fifth output line 105. 98, a reverse clutch line 124 is branched off to the actuator 44a of the reverse clutch 44. Therefore, in the R range, the low reverse brake 46 and reverse clutch 44 are always engaged. Incidentally, the reverse clutch line 124 is also provided with an N-R accumulator 99 for buffering when the reverse clutch is engaged. Further, a line 125 branched from the fifth output line 105 is connected to the regulator valve 6.
1 to the pressure increasing side, and the line pressure is increased in the R range. In addition to the above configuration, this hydraulic circuit 60 is provided with a lock-up valve 150 for actuating the lock-up clutch 26 in the torque converter 20 shown in FIG. A torque converter line 151 is led from the regulator valve 61 to this valve 150, and
The main line 10 is connected to the control port 150b at one end.
0 is connected as a control line 152. The lock-up solenoid valve 153 provided in the control line 152 is connected to the control circuit 2.
When the signal D from 00 is turned ON, the control pressure in the control port 150b is drained and the spool 150a is positioned on the right side, so that the torque converter line 151 is connected to the line 154 leading into the torque converter 20. As a result, the internal pressure of the torque converter 20 increases and the lock-up clutch 26 is engaged. Also,
When the solenoid valve 153 is turned off and control pressure is introduced into the control port 150b, and the spool 150a moves to the left, the torque converter line 151 communicates with the lock-up release line 155, and the torque converter 20
A lockup release pressure is introduced within the lockup clutch 26 to release the lockup clutch 26. As described above, the signals A from the control circuit 200,
B and C control the first to third solenoid valves 7 according to the operating range indicated by the vehicle speed and throttle opening.
6, 77, 78 are the combination patterns shown in Table 2.
The spool 7 of each shift valve 71, 72, 73 corresponding to this pattern is turned on and off.
1a, 72a, 73a and the selection position of the manual valve 64.
1 to 46 are selectively engaged, and the gear position in each range is set as shown in Table 1. However, the control circuit 200 is
During the -3 downshift, the ON/OFF pattern of each of the solenoid valves 76 to 78 is changed from the 4th speed pattern shown in Table 2 to the 3rd speed pattern via the intermediate pattern. As this intermediate pattern, first and second intermediate patterns are set as shown in Table 3, and the control circuit 200 controls the vehicle speed and throttle opening as shown in FIG. In addition to signals E and F from sensors 201 and 202 shown respectively, a downshift signal G from constant speed traveling device 203;
The signal H from the idle switch 204 that detects whether the throttle opening is fully closed is input, and 4-3
Based on these signals during downshifting, the downshifting is accelerated depending on whether the vehicle speed is higher than a predetermined vehicle speed (for example, 40 km/h) V ₀ or when the downshifting signal G is output from the constant speed traveling device 203. Either the first or second intermediate pattern is selected depending on whether the pattern is for deceleration or for deceleration. In this embodiment, as shown in parentheses in Table 3, a second pattern is set in which the first solenoid valve 76 is OFF in the third gear after the 4-3 shift, and the set vehicle speed V ₀ '( For example, 40km/
h) This second pattern is adopted in the following three speeds.

[Table] Next, the shift operation during 4-3 shift, which is a characteristic part of the present invention, will be explained according to the flowchart of FIG. 3 showing the operation of the control circuit 200. First, in step _S1 , the control circuit 200 reads the vehicle speed (or the rotational speed of the turbine shaft 27, which can be converted to vehicle speed using the gear ratio of the current gear position) and the throttle opening. In step _S2 , it is determined whether the current gear position is 4th gear or not. If the gear position is other than 4th gear, normal gear change control is performed in step _S3 . On the other hand, if the current gear position is 4th gear,
The control circuit 200 inputs each input signal E to H in step _S4 .
Based on this, it is determined whether it is time to downshift to third gear. If it is _time to downshift, the actual vehicle speed is compared with a preset predetermined vehicle speed _V0 in step _S5 . In S ₆ and S ₇ , control signals A to C are outputted to the first to third solenoid valves 76 to 78 for a predetermined time T so that the first intermediate pattern shown in Table 3 is achieved (the fourth area in the figure). Further, when the vehicle speed is higher than the predetermined vehicle speed _V0 , the control circuit 200 executes steps _S5 to _S8 , so that the downshift operation is performed by the constant speed traveling device 2.
It is determined whether or not it is due to the shift down signal G from 03. If the downshift is not due to this signal G but during normal driving, then at steps _S9 and _S10 , for a predetermined time T,
Control signals A to C are outputted to the first to third solenoid valves 76 to 78 so as to form the second intermediate pattern shown in Table 3 (area in FIG. 4). On the other hand, if the shift down operation is based on the shift down signal G from the constant speed traveling device 203 while the vehicle is running at a constant speed, the control circuit 200 executes steps _S8 to _S11 to shift down from the idle switch 204. Based on the signal H, it is determined whether the throttle opening is fully closed. If it is not fully closed, in other words, the downshift during constant speed driving causes the vehicle speed to exceed a certain permissible limit compared to the set vehicle speed, even though the throttle opening has been increased to a predetermined limit when climbing a slope, etc. If the downshift is for acceleration due to the shift down, the control circuit 200 executes steps S ₆ and S ₇ to maintain the solenoid valve 76 for a predetermined period T.
Control signals A to C are outputted so that patterns .about.78 become first intermediate patterns. In addition, if it is determined in step _S11 that the throttle opening is fully closed, that is, even though the downshift during constant speed driving has caused the throttle opening to be fully closed when going downhill, etc. If the downshift is performed for deceleration because the vehicle speed has increased beyond a certain allowable limit from the set vehicle speed, the control circuit 200
executes steps S ₉ and S ₁₀ above and waits for the predetermined time T.
During this period, control signals A to C are output so that the patterns of the solenoid valves 76 to 78 become the second intermediate pattern. The control circuit 200 then performs the step
Step _S12 is executed to determine whether the vehicle speed is greater than or equal to the predetermined vehicle speed _V0 ', and if the vehicle speed is greater than or equal to the predetermined vehicle speed _V0 ', step _S13 is executed.
so that the 3rd speed first pattern shown in Table 3 (the pattern in which the first solenoid valve 76 is ON) is achieved, and if the vehicle speed is less than the predetermined vehicle speed V ₀ ', the step
At _S14 , control signals A to C are output to each of the solenoid valves 76 to 78 so as to achieve the second pattern of the third speed (a pattern in which the first solenoid valve 76 is OFF), and the shift to the third speed is completed. By the way, the ON/OFF pattern of the first to third solenoid valves 76 to 78 in 4th gear is [ON, OFF].
OFF, ON], and the hydraulic circuit 6 shown in FIG.
The spools 71a to 73a of the 1-2, 2-3, and 3-4 shift valves 71 to 73 in FIG. line 113
The 3-4 clutch pressure is supplied and is always engaged, and in addition to the forward clutch 41, the 2-4 brake 45 and the 3-4 clutch 43 are engaged. In addition, 3 of each solenoid valve 76 to 78
In the case of the first pattern, [ON,
OFF, OFF], and each shift valve 71~
73 spools 71a to 73a are respectively right, left,
Therefore, in addition to the above-mentioned 4th speed state, servo release pressure is supplied through the line 116 to release the 2-4 brake 45, and coast clutch pressure is supplied through the line 117 to release the 2-4 brake. 42 is concluded. On the other hand, the first intermediate pattern is [OFF,
OFF, ON], so if this first intermediate pattern is selected during 4-3 gear shifting, the first solenoid valve 76 switches in the order of ON → OFF → ON,
Also, the third solenoid valve 78 is ON→ON→
Switch in order of OFF. Then, by switching the first solenoid valve 76 between ON and OFF as described above, the spool 71a of the 1-2 shift valve 71 moves from right to left to right in the drawing of FIG. As shown by reference numeral A in FIG. 5a, the servo apply pressure is drained at the start of the shift and once begins to decrease, and then is supplied again after a predetermined time T has elapsed and rises to a predetermined value. Further, since the third solenoid valve 78 is switched from ON to OFF after a predetermined time T has elapsed after the start of gear shifting, the supply of servo release pressure and coast clutch pressure starts as shown by symbols B and C in FIG. is delayed by a time T from the start of the decrease in the servo apply pressure.
As a result, the engagement force of the 2-4 brake 45 starts to decrease from the start of the shift, as indicated by the symbol D, but since the servo release pressure is supplied slowly, it is released slowly. Furthermore, since the engagement of the coast clutch 42 that operates the engine brake in 3rd gear is delayed, the 2-4 brake 45 remains in the half-clutch state (as shown in the diagonal diagram in FIG. will be transferred. As a result, when the first intermediate pattern is selected, that is, when the vehicle speed is less than the predetermined vehicle speed V ₀ and a 4-3 shift is performed in a low vehicle speed region that does not require engine braking, and when the vehicle speed is equal to or higher than the predetermined vehicle speed V ₀ , Even if the vehicle is traveling at a constant speed, the shift shock can be effectively reduced during the 4-3 shift for acceleration. On the other hand, the first to third solenoid valves 76 to
The second intermediate pattern of 78 is [OFF, OFF,
OFF], so when this second intermediate pattern is selected during the 4-3 gear shift, the first solenoid valve 76 is switched in the order of ON → OFF → ON as in the case of the first intermediate pattern described above. For,
The third solenoid valve 78 switches in the order of ON→OFF→OFF. In other words, in this case, the third solenoid valve 78 switches from ON to OFF at the start of gear shifting, and therefore, as shown by the symbols E and F in FIG. and the supply of coast clutch pressure is started. As a result, as shown by the symbol G, the 2-4 brake 45 is released quickly after the start of the shift, and the coast clutch 42 is also engaged immediately after the start of the shift. In this way, the vehicle speed during normal driving is set to the predetermined vehicle speed.
V 4 for deceleration during 4-3 shifting in a high vehicle speed range of ₀ or higher, and when driving at a constant speed in the same high vehicle speed range
- When shifting to 3rd gear, in other words, when changing from 4 to 3 in a state where engine braking is required, the shift to 3rd gear where engine braking is activated will occur quickly, resulting in a delay in engine braking. The idle running state is avoided. In this embodiment, when the vehicle speed is below the predetermined vehicle speed V ₀ ', the
- The first solenoid valve 76 is activated in 3rd gear after the 3rd gear shift.
The second pattern of OFF is adopted. in this case,
The solenoid valve 76 is turned on during 4-3 gear shifting.
It switches in the order of →OFF →OFF, and after the servo apply pressure is drained at the start of gear shifting, it is never supplied again. Therefore, in 3rd gear in this case, only the servo release pressure is supplied to the servo piston 45a, and the 2-4 brake 45 is in a released state, but this is particularly noticeable when shifting to 2nd gear at low vehicle speeds. This is to reduce the shift shock when the gear is down. (Effects of the Invention) As described above, according to the present invention, in an automatic transmission equipped with a constant speed traveling device, especially when a predetermined downshift is performed during constant speed traveling, this downshift is during acceleration. Since the engagement state of the friction engagement element for engine braking during the gear shift is controlled depending on whether the shift is in progress or deceleration, the shift shock is effectively reduced when downshifting during acceleration, and the shift shock is effectively reduced during deceleration. When downshifting, the engine brake is activated quickly to prevent the vehicle from running idle, resulting in a shift state suitable for each case. Particularly, according to the present invention, the above-mentioned effects can be achieved simply by switching and controlling the combination pattern of the operating positions of the shift valves, so there is an advantage that the structure of the hydraulic control circuit does not become complicated.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a schematic diagram showing the mechanical configuration of an automatic transmission, FIG. 2 is a circuit diagram showing a hydraulic circuit, and FIG. 3 is a flow chart showing control operations. , FIG. 4 is a diagram showing the control area,
FIGS. 5a and 5b are diagrams showing changes over time in oil pressure and fastening force during 4-3 gear shifting in the case of passing through the first intermediate pattern and the second intermediate pattern, respectively. 10... automatic transmission, 20... torque converter,
30... Speed change gear mechanism, 41-46... Friction engagement element, 41a-46a... Actuator, 71-7
3...Shift valve, 200...Control means (control circuit), 203...Constant speed traveling device.

Claims (1)

[Claims] 1. A torque converter connected to an engine output shaft, a speed change gear mechanism disposed on the output side of the torque converter, a plurality of friction engagement elements that switch the power transmission path of the speed change gear mechanism, and an actuator for each friction engagement element. The vehicle is configured to have a plurality of shift valves that control the supply and discharge of hydraulic oil to and from the vehicle, and is configured to obtain a plurality of gear stages according to a combination pattern of the operating positions of these shift valves, and maintains the vehicle speed at a set vehicle speed. A shift control device for an automatic transmission equipped with a constant speed traveling device, wherein a downshift signal is output from the constant speed traveling device from a predetermined high gear to a predetermined low gear where engine braking is applied. , an acceleration/deceleration determination means for determining whether a downshift occurs during acceleration or a downshift during deceleration, and when downshifting during acceleration, a combination pattern of the shift valve operating positions is determined from a pattern at a high gear position for engine braking. Switching to a low gear pattern via a pattern in which the friction engagement element is not engaged, and when downshifting during deceleration, the above pattern is changed from a high gear shift pattern to a pattern in which the engine brake friction engagement element is engaged. What is claimed is: 1. A shift control device for an automatic transmission equipped with a constant speed traveling device, characterized in that a control means for switching to a low gear pattern via a constant speed traveling device is provided.