JPS629777B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a control device for controlling the operation of a lock-up mechanism that directly connects the input and output shafts of a torque converter in an automatic transmission installed in a vehicle. (Prior Art) Generally, the torque converter of this type of automatic transmission consists of a pump impeller driven by an engine, a turbine runner connected to a transmission gear mechanism, and a stator disposed at an appropriate angle between the two. The hydraulic oil supplied from the pump impeller to the turbine runner is smoothly returned to the pump impeller by the stator in a direction that does not impede its rotation, and the hydraulic oil is repeatedly circulated without reducing its speed. This increases the torque by increasing the reaction force of the turbine runner, and when the rotational speed of the turbine is slower than the rotational speed of the pump, the increase in torque is large, and as the rotational speed of the turbine approaches the rotational speed of the pump, the torque increases. It has an automatic shifting effect in which the increase in torque becomes smaller. However, on the other hand, there is a drawback that a certain degree of reduction in power transmission efficiency due to slip between the pump and the turbine cannot be avoided, resulting in poor fuel efficiency. Therefore, in order to eliminate such slips, eliminate the drop in power transmission efficiency, and reduce fuel consumption, recently, the input and output shaft of the torque converter is controlled by controlling the hydraulic fluid using electromagnetic means (solenoid valves). A lock-up mechanism (direct-coupled mechanism) is installed that switches the power transmission path from the engine to the transmission gear mechanism by switching on/off with an operated lock-up clutch (direct-coupled clutch), so that the rotational speed of the turbine approaches the rotational speed of the pump. In such operating conditions, it has been proposed to perform lock-up control by directly connecting the pump and turbine using the above-mentioned lock-up mechanism. This lock-up control is, for example,
As described in Publication No. 138559, the engine load is detected based on the rotation speed signal from a rotation speed sensor that detects the rotation speed of the engine's output shaft or an appropriate shaft driven by the engine, and the intake negative pressure. The load signal from the load sensor is compared with the lock-up control line that is set in advance based on the rotation speed and engine load, and the relationship between the rotation speed signal and the load signal, that is, the two signals, is determined. When the determined coordinates are in the lock-up operating zone on the higher rotation side than the lock-up control line, the lock-up mechanism is operated to perform lock-up, and on the other hand, when the determined coordinates are in the lock-up release zone on the lower rotation side than the lock-up control line,
The lockup mechanism is deactivated to release the lockup. In this case, the activation and release of the lock-up mechanism of the torque converter can be automatically controlled under desirable conditions depending on the operating state of the engine, so that fuel consumption can be reduced. However, on the other hand, when the relationship between the rotational speed signal and the load signal, that is, the coordinates determined by the two signals, is in the lockup operation zone on the higher rotational side than the lockup control line,
Even when the engine output is unstable and the throttle opening is fully closed, such as during deceleration operation, the lock-up mechanism will operate and the input and output shafts of the torque converter will be directly connected, which may result in unpleasant vibrations. It was hot. Therefore, as disclosed in Japanese Patent Application Laid-open No. 56-39353, for example, when the throttle opening is fully closed or close to it, the relationship between the rotation speed and the engine load with respect to the above-mentioned lock-up control line has been A lockup control method has been proposed that releases lockup regardless of the situation. However, when the lockup is simply released with the throttle opening fully closed or close to it, the following three problems arise. That is, one of them is that it becomes disadvantageous in terms of fuel efficiency. This will be explained with reference to FIGS. 1 to 6. Figure 1 shows the throttle opening characteristics with respect to the engine speed when the engine is operated alone, i.e. without any load, and the output shaft torque of the engine is maintained at a predetermined value within the range of 0 to 14.5 kg・m. As is clear from Fig. 1, when the output shaft torque of the engine is zero, the throttle opening characteristic with respect to the engine speed is an upward-sloping line, that is, as the throttle opening increases. It can be seen that the engine speed also increases accordingly. Figure 2 shows the output torque characteristics (indicated by the broken line) against the engine speed when the throttle opening is held at a predetermined opening, and the fuel consumption rate from 2 to 12/H.
This shows the same characteristics (shown by the solid line) when the output torque is maintained at a predetermined value within the range of In some cases, it can be seen that the lower the engine speed, the better the fuel efficiency. Among these various characteristics, especially the characteristics when the output torque is zero are shown in FIG. In addition, Figure 4 shows the engine rotational speed characteristics (Fig. (indicated by a broken line) and the turbine output shaft torque characteristic (indicated by a solid line in the figure) with respect to the turbine rotation speed when the throttle opening is maintained at a predetermined opening at intervals smaller than the above-mentioned opening. Furthermore, the fifth
The figure shows the throttle opening characteristic with respect to the turbine rotation speed when the output shaft torque of the turbine is maintained at a predetermined value within the range of 0 to 18 kg·m. As is clear from FIG. 5, the throttle opening characteristic with respect to the turbine rotational speed is almost the same as the throttle opening characteristic with respect to the engine rotational speed shown in FIG. Based on the characteristics of the engine and torque converter explained above, Fig. 6 shows the coordinates showing the relationship between the turbine and engine speed and the throttle opening, and the turbine rotation when the output shaft torque of the turbine is zero. The line Lo shows the throttle opening characteristics with respect to the number and the turbine rotation speed is 2000 rpm.
Lines showing throttle opening characteristics with respect to engine speed and 4000rpm, respectively.
It depicts L ₂ ooo and L ₄ ooo. In this figure 6, the turbine rotation speed is now 2000 rpm.
If we analyze the throttle opening characteristics with respect to engine speed when , with reference to line L ₂ ooo, we get
In this way, when the turbine rotation speed is 2000 rpm and the throttle opening is varied in the range of 0 to 100%, the engine rotation speed will fluctuate in the range of approximately 1700 to 2700 rpm, and the throttle opening will be approximately 8%, or approximately 7 degrees 2 minutes. When the rotation speed is , the rotation speed increases above the turbine rotation speed, and when the throttle opening is lower than that, the rotation speed decreases below the turbine rotation speed. That is, there is a characteristic that the engine rotational speed changes in magnitude with respect to the turbine rotational speed with the point where the turbine output shaft torque becomes zero as a boundary. Therefore, under such characteristics of the engine and torque converter, the above-mentioned Japanese Patent Application Laid-Open No.
Considering the control characteristics of the lock-up control method disclosed in Publication No. 39353, in this conventional control characteristic, the lock-up is released only when the throttle opening becomes zero, so as shown in FIG. If the throttle opening drops beyond line Lo, which indicates the throttle opening characteristics with respect to the turbine rotational speed when the turbine output shaft torque is zero, for example, if the turbine rotational speed is 2000 rpm, the throttle opening will change as described above. degree is about 8~
0%, the lockup mechanism continues to be activated. Therefore, even though the engine speed should actually be lower than the turbine speed, the engine speed is raised to the turbine speed for the lock-up operation. As can be seen from FIG. 3, this consumes more fuel than necessary, which goes against the original purpose of reducing fuel consumption by the lock-up mechanism. The second problem is that the throttle opening is zero (fully closed).
A large torque shock occurs during lockup when returning to an increased non-deceleration operating state. That is, in the conventional lockup control method described above, lockup is released when the throttle opening becomes zero. Therefore, the throttle opening should be changed from zero to the line shown in Figure 6.
When the value is increased beyond Lo, the lock-up mechanism is activated immediately with the increase. In other words,
Due to the delay in the rise of the engine speed with respect to the increase in throttle opening, the engine speed is locked up while it is rotating at a lower speed than the turbine speed, and as a result, a large torque is generated due to the difference in speed between the two. A shot occurs. Furthermore, the third problem is that the engine braking force (engine braking force) does not correspond to the throttle opening when the vehicle is decelerating, and a sudden change point occurs in the engine braking force. In other words, Figure 7 shows how the driving force changes when the accelerator opening (throttle opening) is gradually decreased in the conventional control method, and the accelerator opening decreases when the driving force is zero. When the lock-up mechanism is not operating, the change in driving force is shown by a broken line, whereas when the lock-up mechanism is operating, the driving force is forcibly lowered by the turbine, so the change is shown by a solid line. The driving force becomes as shown by the dotted line, which is lower than the driving force when the lock-up is not activated, as shown by the broken line. Therefore, when the accelerator opening is fully closed in this state and the lockup is released, the driving force is rapidly increased to the driving force when the lockup is not activated, as shown by the broken line, and a shock occurs at that time. On the other hand, when the accelerator opening is gradually increased from fully closed, the process is almost reverse to that described above, and the driving force suddenly decreases at the start of the lock-up operation, causing a shock. (Objective of the Invention) The object of the present invention is to solve the problems of the above-mentioned prior art all at once, namely, to reduce fuel consumption in the engine braking operation region, eliminate sudden changes in engine braking force, and reduce torque shock during lock-up. The objective is to achieve the original purpose of the lockup device and improve the driving feel of a vehicle equipped with an automatic transmission. (Means for Solving the Problems) The configuration of the present invention as a solution to achieve the above object is as shown in FIG. The present invention is based on an automatic transmission equipped with lock-up means d that switches the power transmission path by connecting and disconnecting the input and output shafts of converter b by means of pressure fluid controlled by electromagnetic means e. In this automatic transmission, first, a turbine rotation speed sensor f that detects the output shaft rotation speed of the torque converter b and an engine load sensor g that detects the magnitude of the load on the engine a are provided,
The output signals from the two sensors f and g are detected in the lock-up determining means i by the first
The lockup control line _h1 is compared with the lockup control line h1 to determine whether or not to perform lockup, and the lockup means d is controlled by the control means j based on the lockup on/off signal from the lockup determination means i.
The basic configuration is to control the activation and release of the . Furthermore, for the lockup determination means i,
In advance, when the lock-up means d is operated based on the first lock-up control line _h1 , the operation of the lock-up means d is canceled in response to the transition from the non-decelerating operating state to the decelerating operating state, and the operation is changed from the decelerating operating state to the non-decelerating operating state. a second lockup control line for operating the lockup means d in response to return to the operating state;
Store h ₂ settings. The second lockup control line _h2 is provided with at least a lockup operation control line for operating the lockup means d in response to the return from the deceleration operation state to the non-deceleration operation state, and the lockup operation control line is connected to the engine. It is assumed that the setting is based on the turbine rotation speed and engine load in a state where the output can be considered to be zero. (Function) With this configuration, in the present invention, in addition to the first lockup control line _h1 , the lockup determination means i that determines whether or not to operate the lockup means d is connected to the lockup control line h1. A second lockup control line _h2 is set for controlling the operation of the lockup means d in response to the transition to the operating state and return from the deceleration operating state to the non-deceleration operating state, and this second lockup control line _h2 is It has a lockup operation control line for activating the lockup means d when returning from a deceleration operation state to a non-deceleration operation state, and this lockup operation control line is connected to the turbine rotational speed and the state where the engine output can be considered to be zero. Since the setting is based on the engine load, when the engine a returns from the deceleration operating state to the non-decelerating operating state, the lockup means d is activated when the turbine rotation speed and the engine load are on the second lockup operation control line. In that case, engine a and torque converter b
The difference in rotation between the engine and the turbine is small, which eliminates the large torque shock that occurs during lock-up. Furthermore, during deceleration operation of the engine a, when the engine output is smaller than zero, the operation of the lock-up means d is released, so that the engine a does not over-speed due to the driving force from the turbine.
Due to this, the engine a during deceleration operation
This means that fuel consumption can be reduced. Furthermore, when engine a is in a non-decelerating operating state, lock-up does not occur immediately as the throttle opening increases from the fully closed state, and this eliminates sudden changes in the driving force of engine a, improving the driving feel. be. (Example) Hereinafter, an example as a specific example of the technical means of the present invention will be described in detail based on the drawings from FIG. 9 onwards. FIG. 9 shows the structure of a mechanical part of an electronically controlled automatic transmission A incorporating a lock-up control device according to the present invention and its hydraulic control circuit _A1 . The automatic transmission A includes a torque converter 10 connected to the output shaft 1a of the engine 1, a multi-stage gear transmission mechanism 20 connected to the output shaft 14 of the torque converter 10, and the torque converter 10 and the multi-stage gear transmission mechanism 20. and an overdrive planetary gear transmission mechanism 50 installed between the two. The torque converter 10 includes a pump 1 connected to an output shaft 1a of an engine 1, and a pump 11 connected to an output shaft 1a of an engine 1.
The converter output shaft 14 is coupled to the turbine 12, and the stator 13 is disposed between the pump 11 and the turbine 12. A lock-up clutch 15 is provided between the converter output shaft 14 and the pump 11, and the lock-up clutch 15 is constantly pushed in the engagement direction by the pressure of hydraulic oil circulating within the torque converter 10. The engagement is released by being held in the released state by release hydraulic pressure supplied from the outside. The multi-stage gear transmission mechanism 20 has a front planetary gear mechanism 21 and a rear planetary gear mechanism 22, and the sun gear 23 of the front planetary gear mechanism 21 and the sun gear 24 of the rear planetary gear mechanism 22 are connected by a connecting shaft 25. ing. The input shaft 26 of the multi-gear transmission mechanism 20 is connected to the connecting shaft 25 via a front clutch 27.
In addition, they are connected to an internal gear 29 of the front planetary gear mechanism 21 via a rear clutch 28. A front brake 30 is provided between the connecting shaft 25, that is, the sun gears 23 and 24, and the transmission case. The planetary carrier 31 of the front planetary gear mechanism 21 and the internal gear 33 of the rear planetary gear mechanism 22 are connected to an output shaft 34, and a rear brake is connected between the planetary carrier 35 of the rear planetary gear mechanism 22 and the transmission case. 36 and a one-way clutch 37 are provided. And multi-stage gear transmission mechanism 2
0 is of a conventionally known type and has three forward speeds and one reverse speed, and the desired speed is obtained by appropriately operating clutches 27, 28 and brakes 30, 36. Furthermore, in the overdrive planetary gear transmission mechanism 50, a planetary carrier 52 that rotatably supports a planetary gear 51 is connected to a torque converter 1.
A sun gear 53 is connected to an internal gear 55 via a direct coupling clutch 54. An overdrive brake 56 is provided between the sun gear 53 and the transmission case, and the internal gear 5
5 is connected to an input shaft 26 of the multi-stage gear transmission mechanism 20. The overdrive planetary gear transmission mechanism 50 connects the shafts 14 and 26 in a direct connection state when the direct coupling clutch 54 is engaged and the brake 56 is released, and the brake 56 is engaged and the clutch 54 is released. When released, it connects the shafts 14, 26 in overdrive. On the other hand, the hydraulic control circuit _A1 has an oil pump 100 driven by the output shaft 1a of the engine 1, and transfers the hydraulic oil discharged from the oil pump 100 to the pressure line 101 to the pressure regulating valve 1.
02 adjusts the pressure and guides it to the select valve 103. The select valve 103 is
It has shift positions of 1, 2, D, N, R, and P,
When the shift position is in the 1, 2 and P positions, the pressure line 101 is connected to the ports 103a, 1 of the valve 103.
03b and 103c. Port 103 above
a is connected to an actuator 104 for actuating the aft clutch 28 and holds the aft clutch 28 engaged when the valve 103 is in the position described above. Also, the port 103a is the 1-2 shift valve 11
It is also connected near the left end in the figure 0, and pushes the spool 110a to the right in the figure. Further, the port 103a is connected to the right end of the 1-2 shift valve 110 in the diagram via the first line _L1 , and the second
It is connected to the right end of the 2-3 shift valve 120 in the drawing via a line _L2 , and to the upper end of the 3-4 shift valve 130 in the drawing via a third line _L3 . The first, second and third lines _L1 to _L3 have first, second and third drain lines, respectively.
D ₁ to _{D 3} are branched and connected, and each drain line D ₁ to _{D 3 has a drain line D 1 to D 3 connected} to each other.
The first, second, and third solenoid valves SL ₁ to SL 3 that open and close D ₃ are connected, and when the solenoid valves SL ₁ to _{SL 3 are} energized, the pressure line 101
The pressure in the first to third lines _L1 to _L3 is increased by closing each of the drain lines _D1 to _D3 while communicating with the port 103a. Further, the port 103b of the select valve 103 is connected to the second lock valve 105 via a line 140, and the pressure from this port 103b is transferred to the second lock valve 105.
It acts to push down the spool 105a of No. 5 in the figure. And the spool 10 of the valve 105
5a is in the lower position, lines 140 and 141 are in communication, and hydraulic pressure is applied to the front brake 30.
The engagement side pressure chamber 108a of the actuator 108 of
The front brake 30 is introduced into the front brake 30 and is configured to hold the front brake 30 in the operating direction. Furthermore, a port 103c of the select valve 103 is connected to the second lock valve 105, and the pressure from this port 103c acts to push the spool 105a of the valve 105 upward in the figure. Further, the port 103c is connected to the 2-3 shift valve 120 via the pressure line 106. This line 106 is the second drain line.
Solenoid valve SL ₂ of D ₂ is energized and the second line L ₂
When the pressure inside is increased and the spool 120a of the 2-3 shift valve 120 is moved to the left in the figure, it communicates with the line 107. The line 107 is connected to the release side pressure chamber 108b of the actuator 108 of the front brake 30, and when hydraulic pressure is introduced into the pressure chamber 108b,
The actuator 108 operates the brake 30 in the releasing direction against the pressure in the engagement side pressure chamber 108a. Pressure in line 107 is also directed to actuator 109 of forward clutch 27, causing it to engage and actuate. The select valve 103 also has a port 103d that communicates with the pressure line 101 in the 1 position, and this port 103d reaches the 1-2 shift valve 110 via the line 112, and furthermore the line 1
13 to the actuator 114 of the rear brake 36. The 1-2 shift valve 110 and the 2-3 shift valve 120 move their respective spools 110a, 120a to switch lines when the solenoid valves _SL1 , _SL2 are excited by a predetermined signal, thereby switching the line to a predetermined value. 1-2 brakes or clutches are activated, respectively.
It is configured to perform speed change operations of 1st and 2nd and 3rd speeds. Further, 115 is a cutback valve that stabilizes the oil pressure from the pressure regulating valve 102, 116 is a vacuum throttle valve that changes the line pressure from the pressure regulating valve 102 according to the magnitude of the intake negative pressure, and 11
7 is a throttle back-up valve that assists the throttle valve 116. Further, the hydraulic control circuit _A1 is connected to the above-mentioned 3-3 in order to control the operation of the clutch 54 and brake 56 of the planetary gear transmission mechanism 50 for overdrive.
Actuator 1 controlled by 4 shift valve 130
32 are provided. The engagement side pressure chamber 132a of the actuator 132 is connected to the pressure line 101, and the pressure of the line 101 pushes the brake 56 in the engagement direction. Also, 3-4 above
The shift valve 130 is the above-mentioned 1-2, 2-3 shift valve 1.
10 and 120, when the solenoid valve SL ₃ is energized, its spool 130a moves downward in the figure. Therefore, pressure line 101 and line 1
22 is cut off and line 122 is drained. As a result, the hydraulic pressure acting on the release side pressure chamber 132b of the actuator 132 of the brake 56 disappears, and the brake 56 is actuated in the engagement direction, and the actuator 13 of the clutch 54 is operated.
4 acts to release the clutch 54. Further, the hydraulic control circuit _A1 is provided with a lock-up control valve 133. This lock-up control valve 133 is communicated with the port 103a of the select valve 103 via a fourth line _L4 . Similarly to the drain lines _D1 to _D3 , the line _L4 is connected to a fourth solenoid valve _SL4 as an electromagnetic means.
A fourth drain line _D4 is branched and connected. And the lock-up control valve 13
3, when the solenoid valve SL ₄ is energized to close the drain line D ₄ and the pressure in the line L ₄ increases, the spool 133a cuts off communication between the line 123 and the line 124, and the line 12
4 is drained to move the lock-up clutch 15 in the connecting direction. In the above configuration, the operational relationships between each gear, the lockup, and each solenoid, and the operational relationships between each gear and the clutch and brake are shown in Tables 1 to 3 below.

【table】

【table】

[Table] Next, based on Fig. 10, the above hydraulic control circuit
The electronic control circuit 200 for controlling the operation of _A1 will be described. The electronic control circuit 200 is connected to an input/output device 201.
It includes a RAM 202 and a CPU 203. The input/output device 201 includes an intake passage 2 of the engine 1.
Engine 1 based on the opening degree of throttle valve 3 in
An engine load sensor 204 that detects the magnitude of the load and outputs a load signal S _L , and a converter 10
A turbine rotation speed sensor 205 detects the rotation speed of the output shaft 14 and outputs a turbine rotation speed signal _ST .
and the shift range of the shift lever (select valve 1
03 position) and outputs a shift lever signal S _R.
The output signals S _L , S _T , and S _R from 206 to 206 are inputted to the input device 201 . The input/output device 201 processes the output signals S _L , S _T , and _SR from the sensors 204 to 206 and supplies them to the RAM 202 . The RAM 202 receives these signals S _L , S _T ,
It stores S _R and supplies signals S _L , S _T , S _R or other data to the CPU 203 in response to instructions from the CPU 203 . The CPU20
Reference numeral 3 constitutes a lockup determination means in the present invention. That is, as shown in FIG.
Lu, shift down shift line L _d , first and second lockup operation control lines Ll _N1 , Ll _N2 and first and second lockup release control lines Ll _F1 , Ll _F2 are stored, and the output signal from the RAM 202 is stored. S
_L , S _T , and S _R are connected to the shift-up control line Lu, shift-down control line Ld, and lock-up control line.
Compares with Ll _N1 , Ll _N2 , Ll _F1 , and Ll _F2 to calculate whether or not to shift and whether to lock up, and generates a shift on/off signal and a lockup on/off signal, respectively. I try to do that. Here, the second lockup operation control line _LlN2 is set based on the turbine rotational speed and engine load in a state where the output shaft torque of the engine 1 can be considered to be zero. Further, the CUP 203 also constitutes a control means in the present invention. In other words, CPU203
The calculation results are sent to each of the shift valves 110 and 12 as a speed change control valve via the input/output device 201.
0, 130 _and lock-up control valves ₁₃₃ , respectively. Incidentally, it is preferable that the electric control circuit 200 is constituted by a microcomputer. Next, an example of control of the automatic transmission A by the electronic control circuit 200 will be explained. The program incorporated in this electronic control circuit 200 is the 12th program.
13, FIG. 15, and FIG. 17. That is,
FIG. 12 shows an overall flowchart of shift control, which is first performed from initialization settings. In this initialization setting, first, the ports of each control valve that switches the hydraulic control circuit A ₁ of the automatic transmission A and necessary counters are initialized, the gear transmission mechanism 20 is set to the 1st speed state, and the lock-up clutch 15 is released. Set each state. Thereafter, each working area of the electronic control circuit 200 is initialized to complete the initialization setting. After this initialization setting, after counting by the timer, the select valve 10
A step of reading position 3, that is, shift range, is performed, and it is determined whether the read shift range is range 1 or not. If this determination is YES, the lock-up is released, and then it is calculated whether or not the engine will overrun when downshifting to first gear. Thereafter, it is determined whether overrun occurs based on this calculation, and when this determination is NO, the gear transmission mechanism 20 is shifted to 1st gear, and when YES, the shift valve is operated to shift gear transmission mechanism 20 to 2nd gear. A controlling signal is emitted. Thereafter, the process returns to the original step after being delayed for a certain period of time (for example, 50 msec) in order to set the transition speed of the control loop. On the other hand, when the determination as to whether the shift range is the 1st range is NO, it is then determined whether the shift range is the 2nd range. This judgment is YES
When this is the case, the lock-up is released and the gear transmission mechanism 20 is shifted to the second speed. Further, when the determination is NO, that is, when the shift range is the D range, shift-up speed change control including a shift-up determination is performed based on the shift-up speed change control subroutine shown in FIG. The above-mentioned shift-up speed change control is started by first reading the gear position, that is, the position of the gear transmission mechanism 20, and determining whether or not the read gear position is the fourth speed. When this determination is YES, it is not possible to shift up any further, so the control is immediately terminated.
On the other hand, when the determination as to whether the gear position is 4th gear is NO, read the throttle opening and
The set turbine rotation speed Tsp (map) on the map corresponding to the throttle opening is read by comparing it with the shift-up shift line Lu on the shift-up map shown in FIG. Next, the actual turbine rotation speed Tsp is read out, and the rotation speed Tsp is equal to the above-mentioned set turbine rotation speed _TSP.
(map). When this determination is YES, it is determined whether flag 1 is "1". This flag 1 is set to "1" when a shift-up is executed, and the shift-up state is stored. When the determination for the flag 1 is YES, it is assumed that a shift-up is being performed, and the control is immediately terminated. Also, if the above judgment is NO
If so, the flag 1 is set to "1" and the gear position of the gear transmission mechanism 20 is shifted up by one step. At that time, a lockup release timer is set to release the lockup for a predetermined period of time to prevent a shock during gear shifting, and the control is then terminated. On the other hand, when the determination of the actual turbine rotation speed Tsp with respect to the set turbine rotation speed T _SP (map) is NO, the above shift-up transmission line Lu is multiplied by 0.8 to create a hysteresis as shown by the broken line in FIG. A new shift-up transmission line Lu' is formed, and the set turbine rotational speed T _SP (map) is corrected by the new shift-up control line Lu'.
Then, this modified setting turbine speed Tsp
It is determined whether or not the actual turbine rotational speed Tsp is large with respect to (map). If the determination is YES, the control is left as is, and if the determination is NO, the flag 1 is reset and each control ends.
With the above steps, the subroutine for shift-up speed change control is completed. After execution of such shift-up speed change control, shift-down speed change control including downshift determination is performed based on the shift-down speed change control subroutine shown in FIG. 15. This shift-down speed change control is similar to the above-mentioned shift-up speed change control.
First, the gear position, that is, the gear transmission mechanism 20
The process starts by reading the position of , and determining whether or not the read gear position is the first gear. If this determination is YES, no further downshifts can be performed, so the control is terminated. On the other hand, when the determination as to whether the gear position is 1st speed is NO, the throttle opening is read and compared with the downshift shift line Ld of the downshift map shown in FIG. Read the set turbine rotation speed Tsp (map) on the map. Next, the actual turbine rotation speed Tsp is read out, and it is determined whether the actual turbine rotation speed is smaller than the set turbine rotation speed Tsp (map). When this determination is YES, it is determined whether flag 2 is "1". This flag 2 is set to "1" when a downshift is executed, and stores the downshift state. Then, when the determination for the flag 1 is YES, the control is immediately terminated after seeing that the downshift is being performed. If the above determination is NO, the flag 2 is set to "1" and the gear position of the gear transmission mechanism 20 is shifted down by one stage. At that time, a lockup release timer is set to release the lockup for a predetermined period of time in order to prevent a shock during gear shifting, and the control is then terminated. On the other hand, when the determination of the actual turbine rotation speed Tsp with respect to the above set turbine rotation speed Tsp (map) is NO, the above shift down shift line Ld is divided by 0.8, resulting in hysteresis as shown by the broken line in Fig. 16. A new downshift control line Ld' is formed, and the set turbine rotational speed Tsp (map) is corrected by the new downshift control line Ld'.
In other words, the actual turbine rotation speed Tsp is multiplied by 0.8 to correct the actual turbine rotation speed Tsp. This corrected actual turbine speed Tsp then becomes the uncorrected set turbine speed
It is determined whether or not it is smaller than Tsp(man), and if the determination is YES, the flag 2 is reset, and the control ends. With the above steps, the subroutine for downshift control is completed. After execution of such downshift control, lock-up control including lock-up determination is performed in the 17th step.
This is performed based on the lockup control subroutine shown in the figure. The lockup control is started by first reading the state of the lockup release timer in the shift control and determining whether the timer is "0", that is, whether it has been reset. If this determination is NO, a control signal is issued to release the lockup, and then the control is terminated. On the other hand, when the judgment on the timer is YES, the throttle opening is checked against the first lockup release control line Ll _F1 of the lockup map shown in FIG. 18, and the turbine rotation is set on the map according to the throttle opening. Read the number Tsp(map),
After that, the actual turbine rotation speed Tsp is read out and the turbine rotation speed Tsp is determined as the above-mentioned set turbine rotation speed.
Determine whether it is smaller than Tsp(map). If this determination is YES, the lockup is released and the control ends. On the other hand, when the above judgment is NO, the throttle opening is compared with the second lockup release control line Ll _F2 of the lockup map, and the set turbine rotation speed Tsp (map) on the map corresponding to the throttle opening is read. After that, read out the actual turbine rotation speed Tsp and calculate the turbine rotation speed.
It is determined whether Tsp is larger than the set turbine rotation speed Tsp (map). If this determination is YES, the lockup is released and then the control is terminated. If the judgment is NO, then change the throttle opening to the first position on the lockup map.
Set turbine rotation speed on the map according to the throttle opening by checking with the lock-up operation control line Ll _N1
Tsp (map) is read, and then the read actual turbine rotation speed Tsp is the set turbine rotation speed Tsp.
(map). If this determination is NO, the control ends immediately.
When the judgment is YES, the throttle opening is compared with the second lockup operation control line Ll _N2 of the lockup map, and the set turbine rotation speed Tsp (map) on the map corresponding to the throttle opening is read.
Thereafter, it is determined whether the read actual turbine rotation speed Tsp is smaller than the set turbine rotation speed Tsp (map). If this determination is NO, the control ends immediately. On the other hand, if the determination is YES, a lockup is performed and the control is then terminated. With the above steps, lockup control is completed. After execution of this lockup control, the flow from the initial step is repeated after a certain time delay as shown in the flowchart of FIG. 12 above. Therefore, in this case, the lockup map stored in the CPU 203 includes the first lockup control line Ll _N1 +Ll _F1 used during normal lockup control as shown in FIG. Second lock-up control lines Ll _N2 and Ll _F2 are provided, which are used during the non-deceleration operating state or transition from the non _- decelerating operating state to the decelerating operating state. Turbine rotation speed and engine load (throttle opening) when output torque is approximately zero
In order to operate the lockup when the turbine speed and engine load are on the second lockup operation control line _LlN2 , the torque converter 10 is set based on the lockup when the engine 1 returns from the deceleration state to the non-deceleration state. The difference in rotation between the turbine 12 and the engine 1 is reduced, and the shock when absorbing the inertial energy of the engine 1 corresponding to the difference in rotation is reduced, so that the shock during lock-up can be alleviated. Furthermore, in the deceleration operation range of the engine 1, when the output torque of the engine 1 is lower than zero, the lock-up is released, so the engine 1 is not driven by the turbine 12 and over-speeds.
Therefore, fuel consumption in the deceleration operation range of the engine 1 can be reduced. Furthermore, during deceleration operation of the engine 1, the lock-up is released before the throttle opening reaches the fully open state, so the engine braking force increases smoothly as the throttle opening decreases, and a sudden turning point occurs as before. Never. Further, even during acceleration operation of the engine 1, lock-up does not occur immediately as the throttle opening increases from the fully closed state.
The occurrence of the sudden turning point can be eliminated, thereby improving the driving feel of the vehicle. An example of the method for controlling the automatic transmission A by the electronic control circuit 200 using a microcomputer has been described above with reference to FIGS. 12 to 18. The digital electric circuit will be explained with reference to FIG. 19. Note that the same reference numerals are used for the same parts as in FIGS. 9 to 18. In Fig. 19, 300 detects the driving mode such as power, economy, etc. and outputs the driving mode signal S ₂₃
A mode sensor 301 is a water temperature sensor that detects the temperature of the cooling water and outputs a signal Sc when the cooling water temperature is in a cold state lower than a predetermined temperature or the like. The output terminal of the shift lever sensor 206 indicating the D range is connected to one input terminal of the shift data index signal generating circuit 302.
This shift data index signal generation circuit 30
The mode sensor 300 mentioned above is connected to the other input terminal of 2 via the AD converter 303.
The AD converter 303 applies the mode signal S _M from the mode sensor 300 to a chart C _{1 that shows the power driving mode and the economy driving mode divided into six stages, for example, and outputs a digital mode signal S corresponding to the chart C 1} . Output _Md . The above shift data index signal generation circuit 3
One output terminal of 02 has a shift up map _M1
Shift-up map generation circuit 304 that stores
However, a shift down map generation circuit 305 storing a shift down map _M2 is connected to the other output terminals. Above shift up map
_M1 consists of a one-stage shift-up map, and includes a plurality of shift lines Mfu for one-stage shift-up corresponding to each of the above-mentioned driving modes. Further, the shift down map _M2 is composed of a one-stage shift down map, and includes a plurality of shift lines Mfd for one-stage downshift corresponding to each of the above-mentioned modes. and,
The shift up map generation circuit 304 generates a digital mode signal S _Md when the shift position is in the D range.
In response to the index signal Si generated in response to the
A single shift line Muf for one-stage shift up is read out according to the driving mode indicated by the signal S _Md . On the other hand, when the shift position is in the D range, the shift-down map generation circuit 305 receives the index signal Si in the same manner as the shift-up map generation circuit 304, and selects the index signal Si according to the driving mode indicated by the signal S _Md .
Read out one shift line Mfd for downshifting. In addition, the shift up map generation circuit 304
The engine load sensor 204 (throttle opening sensor) is connected to each other input terminal of the shift down map generation circuit 305 via an AD converter 306.
is connected. This AD converter 306 applies the load signal from the engine load sensor 204, that is, the throttle opening signal S _L , to a chart C ₂ that shows the throttle opening divided into, for example, eight stages between fully closed and fully open. A digital throttle opening signal S _Ld corresponding to this is output. The shift-up map generation circuit 304 receives the digital throttle opening signal S _Ld and converts this signal S _Ld into the shift line Mfu of the first gear shift-up map.
Accordingly, a signal Tf indicating the gear point turbine rotation speed of the first gear shift up according to the current throttle opening degree is generated.
Output. On the other hand, the shift down map generation circuit 305 generates the digital throttle opening signal S _Ld
Then, this signal is compared to the shift line Mfd of the first-stage downshift map, and a signal tf indicating the shift point turbine rotational speed of the first-stage downshift corresponding to the current throttle opening is output. In addition, the shift up map generation circuit 304
and the shift down map generation circuit 305 each have one output terminal, and these output terminals are connected to the first and second discriminators 307 and 30, respectively.
9 is connected to one input end of each of the terminals. The other input ends of the first and second discriminators 307 and 309 are connected to the turbine rotation speed sensor 205 via an AD converter 312. The first discriminator 307 compares the signal Tf and the signal _ST , and when the current turbine rotation speed indicated by the signal Tf is larger than the turbine rotation speed at the shift point for the first shift up indicated by the signal _S30 , the first discriminator 307 determines that The Hi signal that instructs to perform a gear shift up is
When it is small, a low signal is output respectively. The second discriminator 309 compares the signal tf and the signal _ST , and when the current turbine rotation speed indicated by the signal _ST is smaller than the shift point turbine rotation speed for the first-stage downshift indicated by the signal tf, the second discriminator 309 compares the signal tf and the signal ST.
It outputs a Hi signal instructing to downshift, and a Low signal when the level is large. The output terminals of the first and second discriminators 307, 309 selectively receive the Hi signal and Low signal from these discriminators 307, 309, and actually shift up one stage and perform one stage shift from these signals. A determination circuit 313 is connected which generates a signal for performing one of the downshifts. A first gate circuit 314 is connected between the first discriminator 307 and the determination circuit 313. This first gate circuit 314 is designed to prohibit upshifting from 3rd gear to overdrive OD in cold weather, as this may cause problems such as the engine stopping. An output end of the first discriminator 307 is connected to one end, and an AND circuit 317 is connected to the other input end via an inverter 316. The above-mentioned water temperature sensor 301 is connected to one input terminal of this AND circuit 317, and a signal generator that detects the gear position and generates a signal S ₃ rd when the gear position is currently in third gear is connected to one input terminal of the AND circuit 317. 318 is connected. The AND circuit 317 is connected to the water temperature sensor 30
1, the signal Sc from the signal generator 318, and the signal _S3rd , it outputs a Hi signal. This Hi signal is inverted by the inverter 316 and becomes a Low signal, which is input to the other input terminal of the first gate circuit 314. Therefore, when the current gear position is 3rd gear in cold weather, the signal from the first discriminator 307
The Hi signal is not passed through the determination circuit 313, thereby prohibiting shifting from third gear to overdrive in cold weather. Further, the second discriminator 309 is directly connected to the determination circuit 313. When the determination circuit 313 receives the Hi signal from the second discriminator 309, it determines that one-stage downshift control should be performed. 1 range and 2 of shift lever sensor 206
The output terminal indicating the range is directly connected to a determination circuit 313, and the determination circuit 313 fixes the gear to 2nd speed when the gear is in the 2nd range, fixes it to the 1st gear when the gearshift is in the 1st range, and fixes it to the 1st gear if no shift shock occurs. If there is a risk of gear shift shock, the gear is changed stepwise such as 2nd gear, then 1st gear, and finally fixed at 1st gear. The determination circuit 313 has 1-2 at its output terminal.
A first drive circuit 326 for driving the first solenoid valve SL ₁ of the shift valve 110, a second drive circuit 327 for driving the second solenoid valve SL ₂ of the 2-3 shift valve 120, and 3-4. A third drive circuit 328 for driving the third solenoid valve SL ₃ of the shift valve 130 is connected to the four discriminators 307 to 310 and the shift lever sensor 20.
1-2 shift signal S _1-2 which instructs upshifting or downshifting between 1st and 2nd speeds in response to the signal from 6, and upshifting or downshifting between 2nd and 3rd speeds. Instruct to down 2
-3 shift signal S _2-3 and 3-4 shift signal S _3-4 instructing upshifting or downshifting between 3rd gear and overdrive, i.e. 4th gear.
are now occurring selectively. The first drive circuit 326 described above is configured to provide an instruction for either upshifting or downshifting.
−2 shift signal S _1-2 is received, and this shift signal S _1-2
Accordingly, the solenoid of the first solenoid valve _SL1 is energized or deenergized to control the 1-2 shift valve 110, thereby upshifting or downshifting between 1st and 2nd speeds. Also the second
The drive circuit 327 receives the 2-3 shift signal S _2-3 instructing either upshift or downshift, and in response to this shift signal S _2-3
The solenoid of solenoid valve _SL2 is energized or deenergized to control the 2-3 shift valve 120, thereby shifting up or down between 2nd and 3rd speeds. The third drive circuit 328 also receives the 3-4 shift signal S3-4 instructing either upshift or downshift, and receives this shift signal _S3-4 in substantially the same way as the above two drive circuits.
_3-4 shift valve 13 by energizing or de-energizing the solenoid of the third solenoid valve SL ₃ according to S 3-4.
0 and thereby performs upshifting or downshifting between 3rd and 4th speeds. Next, the lockup control system will be explained. This lockup control system includes a first lockup operation map generation circuit 350 that stores a first lockup operation map _M3 , and a first lockup release map that stores a first lockup release map _M5 . A map generation circuit 352 is provided. The above lockup maps _M3 , _M5 are composed of a plurality of lockup control lines _LlN1 and
Equipped with Ll _F1 . The lockup operation map generation circuit 350 and the lockup release map generation circuit 352 have one input terminal connected to the output terminal of the shift data index signal generation circuit 302, and receive the digital mode signal S _Md to generate the shift data. Index signal generation circuit 302
In response to the index signal Si generated by the above-mentioned signal S _Md , the lock-up control lines Ll _N1 and Ll _F1 for lock-up control according to the driving mode indicated by the signal S Md are read out. The lockup activation map generation circuit 350 and the lockup release map generation circuit 352 have the engine load sensor 204 connected to the other input terminals via the AD converter 306,
A digital throttle opening signal S _Ld is received from the converter 306, and this signal S _Ld is applied to the lock-up control lines Ll _N1 and Ll _F1 to establish a standard for lock-up ON and OFF control according to the current throttle opening. Signal T _Lu indicating the range of turbine rotation speed
₁ and t _Lu1 . The output terminals of the lockup operation map generation circuit 350 and the lockup release map generation circuit 352 are connected to one input terminal of the discriminator 330 and the discriminator 332, and the other input terminal of the discriminator 330 and the discriminator 332 is It is connected to the turbine rotation speed sensor 205 via an AD converter 312. On the other hand, a second lockup operation map generation circuit 35 that stores the second lockup operation map _M4
1, and a second lockup release map generation circuit 35 that stores the second lockup release map _M6 .
3 are provided. The second lockup map generation circuits 351 and 353 are connected to control lines Ll _N2 and Ll _F2 , respectively, which are set in advance with reference to zero engine output.
The engine load sensor 204 is connected to its input terminal via the AD converter 306, and the throttle opening signal S _Ld is connected to the control line.
In comparison with Ll _N2 and Ll _F2 , signals T _Lu2 and t _Lu2 are output which indicate the reference turbine rotational speed range for lock-up ON and OFF control according to the current throttle opening. Signal T _L
u2 and _tLu2 are input to a discriminator 331 and a discriminator 333, respectively, and the other input ends of the discriminator 331 and the discriminator 333 are connected to the turbine rotation speed sensor 205 via an AD converter 312. The discriminators 330 to 333 compare the signal _ST with the signals T _Lu1 , T _Lu2 , t _Lu1 , and t _Lu2 , respectively, and determine whether the current turbine rotation speed indicated by the signal S _T is the lock-up activated turbine rotation speed or the lock-up release turbine rotation speed. Instructs to turn lockup ON and OFF when within the range of numbers.
It is designed to output a Hi signal. The output terminals of the discriminator 330 and the discriminator 331 are connected to an AND circuit 3.
34, and the output terminals of the discriminator 332 and the discriminator 333 are respectively connected to an AND circuit 335, and the output terminals of the lock-up control valve 133 are connected to the AND circuit 335, which is closed to inhibit lock-up under conditions described below. It is connected to a fourth drive circuit 343 for driving four solenoid valves S22 _(j) . The gate circuit 337 is for inhibiting lock-up and is composed of an RS flip-flop circuit.The output terminal of the AND circuit 334 is connected to its set terminal, and the OR circuit 336 is connected to its reset terminal.
An AND circuit 335 is connected thereto. Another input terminal of the OR circuit 336 is connected to the shift lever sensor 206 via an OR circuit 338.
1 range, 2 range, and the output signal of the water temperature sensor 301 are input, so the gate circuit 3
37 is closed when the shift position is other than the D range and when the water temperature sensor is low, and lockup is prohibited. That is, in this embodiment, lock-up control is performed only when the shift position is in the D range and when the engine is warmed up. The other input terminal of the OR circuit 336 is connected via a one-shot generator 339 to an OR circuit 340 which outputs a signal mainly for preventing lock-up during speed change control.
The two input terminals of this OR circuit 340 are directly or indirectly connected to the discriminators 307 and 309 for determining whether to perform shift up or down shift control, respectively. When it is determined that the gear change control should be performed by either of the two, the gate circuit 337 is closed for a certain period of time to prohibit lockup. (Effects of the Invention) Therefore, according to the present invention, lock-up is released when the engine output torque is on the zero line, instead of releasing the lock-up when the throttle opening becomes zero as in the conventional case. As a result, there is no negative drive from the turbine to the engine from the zero line of output torque until the throttle opening is fully closed, preventing engine overspeed in the engine braking operation range. Therefore, it is possible to reduce fuel consumption. In addition, when the torque converter's input and output shafts are directly connected due to the lockup operation, the difference between the engine speed and the turbine speed becomes smaller, so the generation of a large torque shock is reduced. This allows the vehicle to be re-accelerated smoothly, and the engine braking force to be changed smoothly without any sudden changes, thereby improving the driving feel of the vehicle.

[Brief explanation of the drawing]

Figure 1 is a graph showing the output torque characteristics when the engine is rotated without load, Figure 2 is a graph showing the output torque characteristics with respect to engine speed when the throttle opening and fuel consumption are varied. Figure 3 is a graph showing the fuel consumption when the engine is under no load, Figure 4 is a graph showing the engine turbine complete full-open and partial load performance, Figure 5 is a graph showing the turbine torque map, and Figure 6 is the graph showing each throttle opening. FIG. 7 is a graph showing the driving force characteristics of an automatic transmission incorporating a conventional lock-up control device, and FIG. 8 is a block diagram showing the configuration of the lock-up control device for an automatic transmission of the present invention. 9 is an explanatory diagram showing the structure and hydraulic control circuit of the mechanical part of an automatic transmission incorporating a lock-up control device according to an embodiment of the present invention, and FIG. 10 is a schematic diagram showing the electronic control circuit of the automatic transmission. 11 is an explanatory diagram showing a shift-up map, a shift-down map, and a lock-up map. FIG. 12 is an overall flowchart of shift control. FIG. 13 is a flowchart of shift-up shift control. An explanatory diagram showing a shift-up map, FIG. 15 is a flowchart of downshift control, FIG. 16 is an explanatory diagram of a shift-down map, FIG. 17 is a flowchart of lock-up control, and FIG. 18 is a lock-up map. An explanatory diagram showing the
FIG. 2 is a circuit diagram specifically showing an electric circuit that performs the same function as the electric control circuit shown in the figure. a...engine, b...torque converter, c
...speed change gear mechanism, d...lockup means, e
...Electromagnetic means, f...Turbine rotation speed sensor, g
...engine load sensor, _h1 ...first lockup control line, _h2 ...second lockup control line,
i... lockup determination means, j... control means,
A... Automatic transmission, A ₁ ... Hydraulic control circuit, 1...
...Engine, 1a...Output shaft, 10...Torque converter, 11...Pump, 12...Turbine,
13... Stator, 14... Output shaft, 15... Lock-up clutch, 20... Multi-stage gear transmission mechanism, 50... Planetary gear transmission mechanism for overdrive, 100... Oil pump, 103... Select valve, 110 ...1-2 shift valve, 120...2
-3 shift valve, 130...3-4 shift valve, 13
3...Lockup control valve, _L4 ...Fourth line, D4 _... Fourth drain line, _SL4 ...Fourth solenoid valve, 200...Electronic control circuit, 201...
Input/output device, 202...RAM, 203...
CPU, 204...Engine load sensor, 205
... Turbine rotation speed sensor, 206 ... Shift lever sensor, 207 ... Solenoid valve group.

Claims (1)

[Claims] 1. A torque converter connected to the output shaft of the engine, a speed change gear mechanism connected to the output shaft of the torque converter, and a lockup means for connecting/disconnecting the input shaft and output shaft of the torque converter to switch the power transmission path; electromagnetic means for controlling the supply of pressure fluid to the lockup means for operating the lockup means; a turbine rotational speed sensor for detecting the rotational speed of the output shaft of the torque converter; and a sensor for detecting the magnitude of the engine load. input the output signals of the engine load sensor, the turbine rotation speed sensor, and the engine load sensor,
These two output signals are set and stored in the first
A lock-up determining means generates a lock-up on/off signal by comparing it with a lock-up control line, and receives a lock-up on/off signal from the lock-up determining means, and drives and controls the electromagnetic means based on the on/off signal. control means for controlling the activation and release of the lockup means, and the lockup determination means includes a control means for controlling the operation and release of the lockup means, and the lockup determination means is configured to control whether the lockup means changes from a non-decelerated operating state to a decelerated operating state when the lockup means is activated based on the first lockup control line. A second lockup control line is set and stored in advance for deactivating the lockup means in response to the transition and activating the lockup means in response to the return from the deceleration operation state to the non-deceleration operation state. The lock-up control line is set based on at least the turbine rotational speed and engine load in a state where the engine output can be considered to be zero, and is a lock-up operation control for operating the lock-up means in response to the return to the non-deceleration operating state. 1. A lock-up control device for an automatic transmission, characterized by having a line.