JPS6146702B2 - - 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 variable speed 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. , the reaction force of the turbine runner is increased to increase the torque; 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 gear shifting effect in which the increase in speed is reduced. 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. It has been proposed to perform lock-up control under such operating conditions 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 in the vicinity, the relationship between the rotation speed and the engine load with respect to the above-mentioned lock-up control line has been determined. 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, FIG. 5 shows the throttle opening characteristic with respect to the turbine rotational 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. A line L ₀ showing the throttle opening characteristic with respect to the engine speed and a line showing the throttle opening characteristic with respect to the engine speed when the turbine speed is 2000 rpm and 4000 rpm, respectively.
It depicts L ₂₀₀₀ and L ₄₀₀₀ . In Fig. 6, if we analyze the throttle opening characteristic with respect to the engine rotation speed when the turbine rotation speed is 2000 rpm with reference to line L ₂₀₀₀ , we can see that the throttle opening characteristic when the turbine rotation speed is 2000 rpm is If you change it in the range of 0 to 100%, the engine speed will fluctuate in the range of approximately 1700 to 2700 rpm,
When the throttle opening is about 8%, that is, about 7 degrees and 2 minutes, the rotational speed increases above the turbine rotational speed, and when the throttle opening is less than that, the rotational speed decreases below the turbine rotational 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 the line _L0 , which indicates the throttle opening characteristic 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 3~0
%, 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 a large torque shock occurs when the lockup is activated and released. That is, in the conventional control method described above, lockup is released when the throttle opening is zero. Therefore, when the throttle opening is increased from zero to beyond the line _L0 shown in Figure 6, the engine speed will be lower than the turbine speed due to the delay in the rise of the engine speed relative to the increase in the throttle opening. However, the torque difference between the two causes a negative torque shock (in the direction of deceleration). On the other hand, when the throttle opening decreases, if the throttle opening drops beyond the line _L0 in FIG. It is driven by. Then, the lockup is released only when the throttle opening becomes zero, so the turbine is subjected to large load fluctuations at that time, resulting in a torque shock. 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, in this state, when the accelerator opening is fully closed 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. Therefore, instead of activating or deactivating the lockup depending on whether or not the throttle opening is zero, as in the conventional lockup control method described above, the engine load and turbine rotation speed are By using a line (L ₀ shown in Figure 6) where the output shaft torque of the engine is approximately zero, which is preset from the relationship, it is possible to solve the problems of the above-mentioned conventional technology all at once. . However, in that case, the line where the output shaft torque of the engine becomes zero is when a load other than the running load of the vehicle is applied to the engine, such as a cooler load for driving the cooler or an electrical load for driving the generator. When the engine speed increases, so-called idle up, the engine speed changes along with the idle up. Therefore, lock-up control becomes unambiguous, and there is a risk that its accuracy may decrease. (Object of the Invention) An object of the present invention is to provide an output shaft torque zero line in which the output shaft torque of the engine is zero when the output shaft torque zero line is used as the lock-up on/off control line as described above. It is possible to always maintain an optimal lock-up control line even when the load varies depending on loads other than the load, thereby improving fuel efficiency during deceleration operation of the engine, alleviating shock during lock-up on/off, and reducing sudden changes in engine braking force. An object of the present invention is to improve the control accuracy in lock-up control of an automatic transmission while preventing the occurrence of such problems. (Structure of the present invention) In order to achieve the above object, the structure of the present invention is as follows.
As shown in the figure, a lockup means d connects and disconnects the input and output shaft of a torque converter b provided between an engine a and a speed change gear mechanism c of an automatic transmission to switch the power transmission path, and the lockup means d
an electromagnetic means e for controlling the supply of pressure fluid to the lockup means d for the operation of the engine, a turbine rotation speed sensor f for detecting the turbine rotation speed of the torque converter b, and an engine for detecting the magnitude of the load on the engine a. Load sensor g and both of the above sensors f, g
a lock-up determining means i for generating a lock-up on/off signal by comparing each output signal from the lock-up with a preset normal first lock-up control line _h1 ; control means j for controlling the activation and release of the rope means d through drive control of the electromagnetic means e;
It is equipped with Further, the lockup determining means i stores a second lockup control line _h2 for operating the lockup means d, which is preset based on the turbine rotation speed and engine load in a state where the engine output can be considered to be zero, The second
The lock-up determination is also made using the lock-up control line _h2 , and the second lock-up control line _h2 is corrected by the correction means k in accordance with the idle up amount of the engine a corresponding to the throttle opening. This is how it was done. (Effects of the Invention) Therefore, according to the present invention, the criteria for determining the operation of the lock-up means for connecting and disconnecting the input and output shafts of the torque converter of an automatic transmission is based on the assumption that the output shaft torque of the engine is approximately zero. By correcting the lock-up control line, which is set based on the relationship between the turbine rotational speed and the engine load, in accordance with the amount of engine idle up, the lock-up control line is set based on the relationship between the turbine rotation speed and engine load. The range can be set optimally, thus solving the problems of the prior art, namely improving fuel efficiency during deceleration operation of the engine, alleviating shock when lock-up is turned on and off, and preventing generation of engine braking force. However, it is possible to improve the control accuracy in lock-up control of the automatic transmission. (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 11 connected to an output shaft 1a of an engine 1, and a pump 11 connected to an output shaft 1a of an engine 1.
A stator 13 is provided between the pump 11 and the turbine 12, and the converter output shaft 14 is coupled to 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 the 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 55 is connected to the input shaft 26 of the multi-gear transmission mechanism 20. In the overdrive planetary gear transmission mechanism 50, when the direct coupling clutch 54 is engaged and the brake 56 is released, the overdrive planetary gear transmission mechanism 50
When the brake 56 is engaged and the clutch 54 is released, the shafts 14 and 26 are coupled in an overdrive state. 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 each shift position of 1, 2, D, N, R, 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. Furthermore, the port 103a is connected to the right end of the 1-2 shift valve 110 in the diagram through 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 . First, second and third drain lines D ₁ , D ₂ and D ₃ are branched and connected to the first, second and third lines L ₁ , L ₂ and L ₃ , respectively. First, second, and third solenoid valves SL ₁ to SL ₃ that open and close the drain lines D ₁ to _{D 2} are connected to the drain lines D ₁ to D ₃ , respectively, and the above three solenoid valves SL ₁ to SL ₃ , when excited, increases the pressure in the first to third lines L1 to _L3 by closing each drain line _D1 to _D3 while the pressure line ₁₀₁ and port 103a are in communication. It's summery. 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 3.
Engagement side pressure chamber 108 of actuator 108 of 0
a 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 103 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. When the solenoid valves SL ₁ and SL ₂ are excited by a predetermined signal, the 1-2 shift valve 110 and the 2-3 shift valve 120 move the respective spools 110a and 120a to switch lines, thereby switching the line to a predetermined value. The brake or clutch is activated and 1-2 respectively.
It is configured to perform speed change operations of 1st, 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 117
is a throttle back-up valve that assists this throttle valve 116. The hydraulic control circuit A ₁ also includes an actuator 132 controlled by the 3-4 shift valve 130 in order to control the clutch 54 and brake 56 of the overdrive planetary gear transmission mechanism 50.
is provided. . The engagement side pressure chamber 132a of the actuator 132 is connected to the pressure line 101, and the brake 5 is
6 in the engagement direction. Further, the 3-4 shift valve 130 is replaced by the 1-2, 2-3 shift valve 11.
0,120, when the solenoid valve SL ₃ is energized, its spool 130a moves downward in the figure. Therefore, pressure line 101 and line 12
2 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 134 of the clutch 54 is actuated.
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 stage, the lockup, and each solenoid, and the operational relationships between each gear stage, clutch, and brake are shown in Tables 1 to 3 below.

【table】

【table】

[Table] Next, based on Fig. 10, the above hydraulic control circuit A ₁
An electronic control circuit 200 for controlling the operation will be described. The connected electronic control circuit 200 and the 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 that detects the rotation speed of the output shaft 14 and outputs a turbine rotation speed signal S _I ;
and the shift range of the shift lever (select valve 1
03 position) and outputs a shift lever signal _S ), the accelerator opening sensor 207 which outputs the accelerator fully closed signal S _A is connected, and the output signals S _L ,
S _T , S _R , and S _A are input to the input device 201 . The input/output device 201 is the sensor 2
Output signals S _L , S _T , S _R , S _A from 04 to 207
is processed and supplied to the RAM 202. The RAM20
2 stores these signals _SL , _ST , _SR , _SA, and supplies these signals _SL , _ST , _SR , _SA or other data to the CPU 203 in response to instructions from the CPU 203. do. The CPU 203 constitutes a lockup determination means according to the present invention. In other words, as shown in FIG.
_U , downshift shift line L _d , first and second lockup operation control lines L _N1 , L _N2 , and first and second lockup release control lines L _F1 ,
L _F2 is stored, and the output signals S _L , S _T , S _R from the RAM 202 are transmitted to the shift up control line L _U , the shift down control line L _d and the lock up control lines L _N1 , L _N2 , L _F1 , L A comparison is made with _F2 to determine whether or not to shift and whether or not to lock up.
It is designed to generate an off signal. Here, the second lockup operation control line L _N2 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 CPU 203 also constitutes a correction means in the present invention. In other words, CPU203
detects the throttle opening based on the engine load signal S _L when receiving the output signal S _A from the RAM 202, and detects a load other than the running load applied to the engine 1, such as a cooler load for driving the cooler or a generator. When the throttle opening is slightly increased from zero in order to increase the engine speed slightly to the normal idle speed for driving the electric load, etc. to perform so-called idle up, the throttle opening is increased. In other words, the second lock-up control lines L _N2 and L _F2 are set to the high opening side (the first
1). Furthermore, the CPU 203 also constitutes a control means in the present invention. In other words, CPU20
The calculation result of step 3 is sent via the input/output device 201,
Each of the above shift valves 110 and 12 as a speed change control valve
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 the 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, a timer counts, the throttle opening is read based on a signal from the throttle opening sensor 207, and then it is determined whether the accelerator opening is in a fully closed state. If this determination is YES, the throttle opening degree is read and the difference between the throttle opening degree and the preset and stored fully closed throttle opening degree is stored in the memory, and then the process moves to the next step.
On the other hand, if the determination is NO, the process immediately moves to the next step. In the next step, select valve 103
The position of , that is, the shift range is read, and it is determined whether or not the read shift range is the 1st range. 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 or not overrun occurs based on this calculation, and when the determination means is NO, the gear transmission mechanism 20 is shifted to 1st speed, and when YES, the gear transmission mechanism 20 is shifted to 2nd speed. A signal is issued to control the 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 judgment as to whether the gear position is 4th speed is NO, read the throttle opening, compare it with the shift-up shift line L _u of the shift-up map shown in Fig. 14, and adjust the throttle opening according to the throttle opening. Set turbine rotation speed T _sp on the map
Read (map). Next, the rotation speed T _sp is read out, and the rotation speed T _sp is equal to the above-mentioned set turbine rotation speed T _sp
(map) Determine whether it is greater than or not. 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 T _sp with respect to the set turbine rotation speed T _sp (map) is NO, the above shift-up speed change line L _u is multiplied by 0.8 to create hysteresis as shown by the broken line in FIG. A new shift-up control line L _u ' is formed, and the set turbine rotational speed T _sp (map) is corrected by the new shift-up control line L _u '.
Then, this modified set turbine rotation speed T _sp
It is determined whether or not the actual turbine rotational speed T _sp is large with respect to (map). If the determination is YES, the control is left as is; if the determination is NO, 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 out the position of the vehicle and determining whether the read gear position is the first speed or not. If this determination is YES, no further downshifts can be performed, and the control is then 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 T _sp (map) on the map. Next, the actual turbine rotation speed T _sp is read and it is determined whether the actual turbine rotation speed is smaller than the set turbine rotation speed T _sp (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. In addition, if the above judgment is NO, flag 2 is set to "1" and gear transmission mechanism 20 is
Shift down the gear position by one gear. 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 then the control is terminated. On the other hand, when the determination of the actual turbine rotation speed T _sp with respect to the set turbine rotation speed T _sp (map) is NO, the above shift down shift line Ld is divided by 0.8 to generate hysteresis as shown by the broken line in FIG. A new downshift control line Ld' is formed with a new downshift control line Ld', and the set turbine rotational speed T _sp (map) is corrected by the new downshift control line Ld'.
In other words, the actual turbine rotation speed T _sp is corrected by multiplying _it by 0.8. This corrected actual turbine speed T _sp then becomes the uncorrected set turbine speed T.
It is determined whether or not it is smaller than _sp (map), 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 for releasing the lockup is issued and then the control is terminated. On the other hand, when the determination for the timer is YES, the throttle opening is checked against the first lockup release control line L _F1 of the lockup map shown in FIG. 18, and the turbine rotation is set on the map corresponding to the throttle opening. The number T _sp (map) is read, and then the actual turbine rotation speed T _sp is read to determine whether the turbine rotation speed T _sp is smaller than the set turbine rotation speed T _sp (map).
If this determination is YES, the lockup is released and the control ends. On the other hand, the above judgment
If NO, the difference between the throttle opening stored in the initial step of the shift control and the throttle fully closed opening is read from the memory;
The throttle opening is corrected by adding or subtracting the opening difference to the current throttle opening. That is, the second lockup release control line L _F2 is corrected to the higher opening side by the opening difference to form a new second lockup release control line L _F2 '. Next, the corrected throttle opening is compared with the second lockup release control line L _F2 of the lockup map to read the set turbine rotation speed T _sp (map) on the map corresponding to the throttle opening, and then the actual The turbine rotation speed T _sp is read out, and it is determined whether the turbine rotation speed T _sp is larger than the set turbine rotation speed T _sp (map). If this determination is YES, the lockup is released and then the control is terminated. If the judgment is NO, then the throttle opening before the above correction is compared with the first lockup operation control line _LN1 of the lockup map, and the set turbine rotation speed T on the map corresponding to the throttle opening is checked. _sp (map) is read, and then it is determined whether the read actual turbine rotation speed T _sp is larger than the set turbine rotation speed T _sp (map). If this determination is NO, the control ends immediately. If the determination is YES, the difference between the throttle opening degree and the throttle fully closed opening degree stored in the initial step of the shift control is determined, as in the step of checking with the second lockup release control line _LF2 . The throttle opening degree is corrected by reading out the degree difference from the memory and adding or subtracting the opening degree difference from the current throttle opening degree. In other words, the second lockup operation control line L _N
A new second lockup operation control line L _N2 ' is formed by correcting the second lockup operation control line L _N2 ' to the higher opening degree side. Next, the corrected throttle opening is compared with the second lockup operation control line L _N2 of the lockup map to read the set turbine rotation speed T _sp (map) on the map corresponding to the throttle opening. It is determined whether the read actual turbine rotation speed T _sp is smaller than the set turbine rotation speed T _sp (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 executing this lockup control, the 12th
After a certain time delay as shown in the flowchart, the flow is repeated from the original step. Therefore, in this case, the second lockup operation control line L of the lockup map shown in FIG.
_N2 is set based on the turbine rotation speed and engine load (throttle opening degree) when the output torque of the engine 1 is approximately zero, and the turbine rotation speed and engine load are set on the second lockup operation control line L _N2 . In order to operate the lockup at a certain time, the rotational difference between the turbine 12 of the converter 10 and the engine 1 during lockup becomes small, and the shock when absorbing the inertia energy of the engine 1 corresponding to the rotational difference becomes small, and thus the lockup is activated. The shock of time can be alleviated. Furthermore, in the braking 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 braking operation region of the engine 1 can be reduced. Furthermore, during braking operation of engine 1, the lock-up is released before the throttle opening reaches the fully closed state, so the engine braking force increases smoothly as the throttle opening decreases, and there is no sudden change point as before. It never happens. 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 change point can be eliminated, and the driving feeling of the vehicle can therefore be improved. Furthermore, the difference in throttle opening from the fully closed throttle opening when the accelerator is fully closed is detected, and the second lockup control lines L _N2 and L _F2 are corrected to the high opening side according to the opening difference. Therefore, even if the engine 1 is idled due to a load other than a driving load such as a cooler load or an electrical load being applied to the engine 1, the lockup range can be optimally set according to the load fluctuation. In addition, since changes in the load on the engine 1 are detected by detecting the throttle opening when the accelerator is fully opened, there is no need to directly detect the type of load other than the traveling load or the load condition, and lock-up control can be performed using a simple system. It can be done with In addition, this detection of load fluctuations is not limited to only during idling, as is the case with systems that detect engine intake boost to detect engine load fluctuations, but can be easily performed even while the vehicle is running, so it is stable at all times. The lockup range can be corrected by Furthermore, since the lock-up range is corrected based on the detection of the throttle opening, it can be applied to either a carburetor type or a fuel injection type fuel supply system, increasing versatility. In the above embodiment, the throttle opening characteristic line for the turbine rotation speed at which the output shaft torque of the engine 1 is approximately zero is made to correspond to the second lock-up operation control line L _N2 , but the second lock-up release control line It may be made to correspond to L _F2 . In that case, the torque shock when lockup is released can be alleviated.

[Brief explanation of the drawing]

Figure 1 is a graph showing the output torque characteristics when the engine is rotated with no load applied, 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 diagram of shift-down speed change control, Fig. 16 is an explanatory diagram showing a shift-down map, Fig. 17 is a flowchart diagram of lock-up control, and Fig. 18 is a flowchart diagram of lock-up control. FIG. 3 is an explanatory diagram showing a map. a...engine, b...torque converter, c...speed 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...Controlling means, k...Correction means, A...Automatic transmission, _A1 ...Hydraulic pressure control circuit, 1...Engine, 1
a... Output shaft, 10... Torque converter, 11... Pump, 12... Turbine, 13... Stator, 14...
Output shaft, 15... Lockup 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, L ₄ ...4th line, D ₄
...4th drain line, SL ₄ ...4th solenoid valve,
200...electronic control circuit, 201...input/output device, 2
02...RAM, 203...CPU, 204...engine load sensor, 205...turbine rotation speed sensor, 2
06...Shift lever sensor, 207...Accelerator opening sensor, 208...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. and control means for controlling the activation and release of the lockup means, and the lockup determination means includes:
As a second lockup control line for operating the lockup means, a second lockup control line preset based on the turbine rotation speed and engine load in a state where the engine output can be considered as zero is stored, and the second lockup control line is stored in advance as a second lockup control line for operating the lockup means. The automatic lock-up control system is configured to also perform lock-up determination based on the second lock-up control line, and further comprises a correction means for correcting the second lock-up control line in accordance with the idle up amount of the engine. Transmission lock-up control device.