JPH06100273B2 - Lockup controller for automatic transmission - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device that controls the operation of a lockup mechanism that directly connects the input and output shafts of a torque converter in an automatic transmission mounted on a vehicle. More specifically, the present invention relates to a control device for a lockup mechanism in an automobile equipped with a constant speed traveling device.

(Prior Art) Generally, a torque converter used in an automatic transmission of this type includes a pump impeller driven by an engine, a turbine connected to a speed change gear mechanism, and a stator fixed between the two. The hydraulic oil filled between them flows into the turbine along the blades of the pump in accordance with the rotation of the pump, torques the turbine, and then returns to the pump through the stator. By repetitively circulating the hydraulic oil, the reaction force of the turbine is increased and the torque is increased.
When the rotational speed of the turbine is lower than the rotational speed of the pump, the torque increases greatly, and the torque increases less as the turbine rotational speed approaches the pump rotational speed. However, on the other hand, there is a drawback in that the power transmission efficiency cannot be reduced to some extent due to the slip between the pump and the turbine, resulting in poor fuel efficiency.

Therefore, in order to eliminate such slip, eliminate the decrease in power transmission efficiency and reduce fuel consumption,
The input / output shaft of the torque converter is intermittently connected by a lockup clutch (direct coupling clutch) operated by the supply / discharge control of hydraulic oil by an electromagnetic means (solenoid valve) to switch the power transmission path from the engine to the transmission gear mechanism. A lock-up mechanism (direct coupling mechanism) is provided, and under an operating state in which the rotation speed of the turbine approaches the rotation speed of the pump, lock-up control is performed by directly connecting the pump and the turbine by the lock-up mechanism. Is proposed. With this configuration, in the region where the rotation of the pump and the turbine are different, a smooth gear shifting action is obtained by the gear shifting action of the torque converter, and in the region where the rotation of the pump and the turbine are close to each other, the lockup clutch is operated to operate the engine output shaft. It is possible to improve fuel efficiency by directly connecting the input shaft of the speed change gear mechanism to this.

On the other hand, in recent years, a constant speed traveling device that automatically maintains the vehicle speed of a vehicle at a desired vehicle speed set by a driver has been put into practical use. This constant speed traveling device sets the vehicle speed as a target value for constant speed traveling by a set operation by the driver when the vehicle speed reaches a desired vehicle speed, and thereafter compares the set vehicle speed with the actual vehicle speed. Then, when there is a difference between the two, the actual vehicle speed is made to match the set vehicle speed by controlling the throttle valve of the engine according to the difference.

However, at the time of operation of this constant speed traveling device, when the vehicle enters an uphill road, the device operates to increase the throttle opening of the engine in order to maintain the vehicle speed. The vehicle speed may gradually decrease even if the throttle opening is fully opened, and may depart from the set vehicle speed.

The following inventions have been proposed in Japanese Patent Application Laid-Open No. 57-121713 as a solution to the above problems in an automobile equipped with a constant speed traveling device. According to the present invention, in a vehicle equipped with an automatic transmission, when the difference between the actual vehicle speed and the set vehicle speed exceeds a predetermined value during operation of the constant speed traveling device, the gear position of the automatic transmission is automatically changed for a certain period of time. It is designed to be downshifted to. According to this, at the time of climbing,
Even if the vehicle speed gradually decreases only by increasing the throttle opening, the required driving force is obtained by downshifting the transmission, and the actual vehicle speed is restored so as to match the set vehicle speed.

However, in the case of the above proposal, there is a problem that a shift shock is likely to occur at the time of downshifting, or at the time of downshifting and upshifting to the original gear stage again when the actual vehicle speed matches the set vehicle speed.

(Object of the Invention) From the above, according to the present invention, the torque is controlled by controlling the lockup when the vehicle speed decreases even when the throttle is fully opened, such as when entering an uphill road when the constant speed traveling device is operating. The purpose of the present invention is to prevent the decrease in vehicle speed relatively smoothly by obtaining the torque increasing action of the converter.

(Structure of the Invention) As shown in FIG. 1, the lock-up control device of the present invention controls the input / output shaft of the torque converter B provided between the engine A and the speed change mechanism C by the electromagnetic means E. In an automatic transmission equipped with a lockup means D for connecting and disconnecting with a fluid to switch a power transmission path, a speed sensor F for detecting a speed of a power transmission system of a vehicle equipped with the automatic transmission, and a load of an engine A An engine load sensor G for detecting the magnitude is provided, and lockup is performed by comparing output signals from the sensors F and G with lockup control lines h and h preset and stored in the lockup determination means I. It is determined whether or not to perform the lockup determination means I.
Based on the lockup operation signal from the lockup control means N, the operation of the lockup means D is basically controlled, and the vehicle speed sensor L and the vehicle speed signal from the vehicle speed setting switch J and the vehicle speed sensor L are detected. In response to the vehicle speed signal from the engine, the actual vehicle speed detected by the vehicle speed sensor L is compared with the set vehicle speed during the operation of the constant speed traveling device K which outputs a signal for controlling the engine output to the engine and maintains the vehicle speed at the substantially set vehicle speed. When the actual vehicle speed decreases from the set vehicle speed by more than a predetermined range determined according to the set vehicle speed, the lockup control means is locked up for a predetermined time set according to the rate of change of the vehicle speed at that time. The lock-up releasing means M for issuing a prohibition signal is provided.

(Example) Hereinafter, the Example of this invention is described based on drawing. First, an example of a mechanical structure and a fluid control circuit of an automatic transmission to which this embodiment is applied will be described with reference to FIG. The automatic transmission 1 is composed of a torque converter 10, a multi-stage speed change gear mechanism 20, and an overdrive speed change gear mechanism 40 arranged between the two.

The torque converter 10 is a pump directly connected to the output shaft 3 of the engine 2 via a drive plate 11 and a case 12.
13, a turbine 14 arranged to face the pump 13 in the case 12, and a stator 15 arranged between the pump and the turbine 14, and an output shaft 16 is coupled to the turbine 14. Has been done. Also, the output shaft 16 and the above case
A lockup clutch 17 is provided between the lockup clutch 12 and the lockup clutch 12. This lockup clutch 17 is a torque converter
The pressure of the working fluid circulating inside 10 is always pressed in the fastening direction, and is released when the releasing fluid pressure is supplied from the outside.

The multi-stage speed change gear mechanism 20 has a front planetary gear mechanism 21 and a rear planetary gear mechanism 22, and sun gears 23, 24 in both mechanisms 21, 22 are connected by a connecting shaft 25. The input shaft 26 to the multi-stage speed change gear mechanism 20 is configured to be connected to the connecting shaft 25 via the front clutch 27 and to the ring gear 29 of the front planetary gear mechanism 21 via the rear clutch 28, respectively. A second brake 31 is provided between the transmission shaft 30 and the connection shaft 25, that is, between the sun gears 23 and 24 of the two planetary gear mechanisms 21 and 22. The pinion carrier 32 of the front planetary gear mechanism 21 and the ring gear 33 of the rear planetary gear mechanism 22 are connected to the output shaft 34, and between the pinion carrier 35 of the rear planetary gear mechanism 22 and the transmission case 30. A low reverse brake 36 and a one-way clutch 37 are provided respectively.

On the other hand, in the overdrive speed change gear mechanism 40, the pinion carrier 41 has the output shaft 16 of the torque converter 10.
The sun gear 42 and the ring gear 43 are coupled by a direct coupling clutch 44. Further, an overdrive brake 45 is provided between the sun gear 42 and the transmission case 30, and the ring gear 43 is connected to the input shaft 26 to the multi-stage transmission gear mechanism 20.

The multi-stage speed change gear mechanism 20 having the above-mentioned structure is conventionally known, and by the selective operation of the clutches 27, 28 and the brakes 31, 36, there are three forward speeds and one reverse speed between the input shaft 26 and the output shaft 34. The ratio is obtained. Further, the overdrive speed change gear mechanism 40 directly connects the output shaft 16 of the torque converter 10 and the input shaft 26 to the multi-step speed change gear mechanism 20 when the clutch 44 is engaged and the brake 45 is released, and the clutch 44 Overdrive coupling the shafts 16, 26 when is released and the brake 45 is engaged.

Next, the fluid control circuit 50 of the automatic transmission will be described.

The working fluid discharged from the oil pump 51 which is constantly driven by the engine output shaft 3 via the torque converter 10 to the main line 52 is guided to the select valve 54 after the hydraulic pressure is adjusted by the pressure regulating valve 53. This select valve 54
Has a range of P, R, N, D, 2,1 and connects the main line 52 to the port a in the D, 2,1 range. This port a is connected to the actuator of the rear clutch 28 via the line 55.
28a, so that the rear clutch 28 is always held in the engaged state in each of the forward ranges D, 2, and 1 described above.

Further, the port is connected to the first, second, third and fourth control lines 56, 57, 5
It communicates with 8,59. These control lines 56 to 59 respectively include a 1-2 shift valve 61, a 2-3 shift valve 62, and a 3-4 shift valve 63.
The lock-up valve 64 is separated from one end thereof, and the control lines 56 to 59 are connected to drain lines 66 and 67, respectively.
68,69 are branched, and the first, second, third and fourth solenoids 71,72,73,76 for opening and closing the drain lines 66 to 69 respectively.
Is provided. These solenoids 71-74 are OFF
Sometimes the drain lines 66-69 are released to make the pressure in the corresponding control lines 56-59 zero, but when the drain lines 66-69 are closed to increase the pressure in the control lines 56-59, 1-2 shift valve 61,2-3 shift valve 62,3-
Spool in the 4-shift valve 63 and the lockup valve 64
61a, 62a, 63a, 64a from the positions shown in the figure (a),
Move in the directions of (b), (c), and (d).

The port a of the select valve 54 also reaches the shift valve 61 via a line 76 branched from the line,
When the spool 61a is moved in the (a) direction by the working fluid from the first control line 56, the spool 61a communicates with the line 77, and further, the second brake 31 is engaged with the actuator 31a via the second lock valve 78 and the line 79. It leads to the side port 31a '. As a result, the working fluid is supplied to the port 31a ', and the second brake 31
Is concluded. Here, the second lock valve 78 is
In the range, the working fluid is supplied from both the ports b and c of the select valve 54 through the lines 80 and 81, and the lines 77 and 79 are held in a communicating state as shown in the drawing. In the two ranges where c is closed, the working fluid is supplied only from the port b and the spool 78
By moving a downward, the lines 80 and 79 are connected. Therefore, in the second range, the second brake 31 is engaged regardless of the state of the 1-2 shift valve 61.

Also, port c that communicates with main line 52 in the D range
Is connected to the above 2 through the one-way throttle valve 82 by the above line 81.
It is led to the -3 shift valve 62. When the spool 62a of the 2-3 shift valve 62 is moved in the (b) direction by the working fluid from the second control line 57, the line 83
To the release side port 31a ″ of the actuator 31a of the second brake 31 and the other to the actuator 27a of the front clutch 27. As a result, the port 31a ″ and the actuator are connected. The working fluid is supplied to 27a, the second brake 31 is released, and the front clutch 27 is engaged.

Further, in the 1st range, the port d of the select valve 54 communicates with the main line 52, the working fluid is guided to the 1-2 shift valve 61 through the line 86, and the spool 61a of the valve 61 is at the position shown in the figure. In addition, the actuator 36a of the low reverse brake 36 is further reached via the line 87. As a result, the low reverse brake 36 is engaged.

Further, in the R range, the port d and the port e communicate with the main line 52, so that the working fluid is guided to the 2-3 shift valve 62 by the line 88, and the spool 62a of the valve 62 is brought to the position shown in the figure. At a certain time, it reaches the release side port 31a ″ of the second brake actuator 31a and the actuator 27a of the front clutch 27 via the line 83 and the lines 84 and 85. As a result, in the R range, together with the low reverse brake 36, the front clutch. 27 is engaged, in which case the port a is closed and the rear clutch 28 is released.

As described above, the main line 52 is selectively switched between the paths by the select valve 54, and at the same time, the connecting side port 45a 'of the actuator 45a of the 3-4 shift valve 63 and the overdrive brake 45 is branched through the branch lines 89 and 90. Have been led to. The line 89 led to the 3-4 shift valve 63 is further communicated with the lines 91 and 92 when the spool 63a of the valve 63 is at the position shown in the drawing, and one line 91 is connected to the actuator 44a of the direct coupling clutch 44. , The other line 92
Is the actuator for overdrive brake 45a
To the open side port 45a ″ of the
When the 4-shift valve 63 is in the state shown in the drawing, working fluid is supplied to both the fastening side and release side ports 45a ′, 45a ″ of the overdrive brake actuator 45a to release the overdrive brake 45, and Direct coupling clutch
44 is in a fastened condition. And 3-4 shift valve 63
When the spool 63a is moved in the (c) direction by the working fluid from the third control line 58, the lines 91 and 92 are drained so that the direct coupling clutch 44 is released and the overdrive brake 45 is engaged. It

Further, the working fluid is guided from the main line 52 to the lockup valve 64 via the branch line 93 passing through the pressure regulating valve 53. Then, when the spool 64a of the valve 64 is in the position shown in the figure, it reaches the inside of the torque converter 10 through the line 94 and disengages the lockup clutch 17 in the torque converter 10. Then, when the spool 64a of the lockup valve 64 is moved in the (d) direction by the working fluid from the fourth control line 59, the line 94 is drained, so that the lockup clutch 17
Are fastened by the fluid pressure in the torque converter 10.

In addition to the above configuration, this fluid control circuit includes a cut-back valve 95 for stabilizing the hydraulic pressure from the pressure regulating valve 53, and a vacuum throttle for changing the line pressure by the pressure regulating valve 53 according to the magnitude of the intake negative pressure. A valve 96 and a throttle backup valve 97 that assists the throttle valve 96 are provided.

With respect to the above configuration, the relationship between the shift solenoids 71 to 73 and the shift speeds in the D range, the relationship between the solenoid 74 and the lockup, and the relationship between the operating states of the clutches and brakes and the shift speeds in each range are respectively described. It is shown in Tables 1, 2 and 3.

Next, the electric control circuit of the automatic transmission 1 will be described with reference to FIG.

As shown in FIG. 3, the electric control circuit 100 is provided with a shift control circuit 101 and a lockup control circuit 102,
A turbine rotation sensor 10 for detecting the rotation speed of the turbine 14 in the torque converter 10 is provided in these circuits 101 and 102.
A turbine rotation signal a from 3 and a throttle opening signal b from a throttle opening sensor 104 that detects the opening of the throttle valve 4 in the engine 2 are input. Then, in response to these signals a and b, the shift control circuit 101 and the lockup control circuit 102
As shown in the figure, the operating state is in either the upshift zone, the downshift zone, or the hold zone according to the shift and lockup map preset according to the turbine speed and the throttle opening. It is also determined whether the lock-up operation or the release is in the zone, and the shift control signal c and the lock-up control signal d are sent to the first to third solenoids 71 to 73 depending on the determination result. Output to the fourth solenoid 74, respectively. As a result, the first to third solenoids 71 to 73 are operated in the ON and OFF states corresponding to the speed stage to be set in accordance with the above-mentioned Table 1, and the automatic transmission 1 operates at the required speed according to the operating range. The fourth solenoid 74 is turned on and off in accordance with Table 2 so that the lockup clutch 17 is operated or released according to the operating region.

On the other hand, the present control device is provided with a constant speed traveling device 105 for maintaining the traveling speed of the automobile at a desired set speed. The constant speed traveling device 105 receives a vehicle speed signal e from a vehicle speed sensor 106 that detects an actual traveling speed V and a vehicle speed setting signal f from a vehicle speed setting switch 107 operated by a driver, and inputs the signal f. The vehicle speed at the time is set as the target speed for constant speed traveling, and the set vehicle speed V ₀ is compared with the actual vehicle speed V indicated by the vehicle speed signal e, and when there is a difference between the two, the difference is eliminated. The throttle control signal g is output to the actuator 108 of the throttle valve 4 so that the actual vehicle speed V matches the set vehicle speed V ₀ .

However, when the difference between the actual vehicle speed V and the set vehicle speed V ₀ exceeds the predetermined value ΔV (for example, 10 km / h) during the operation of the constant speed traveling device 105, the control circuit 100 of the automatic transmission 1 controls this. Lockup release circuit to which the speed decrease signal h indicating
109 and a vehicle speed change detection circuit 110 which receives a vehicle speed signal e from the vehicle speed sensor 106 and calculates a rate of decrease in vehicle speed, that is, a rate of decrease in vehicle speed. In addition,
The predetermined value ΔV may be a constant value or the set vehicle speed.
It may be a value corresponding to the set vehicle speed V _0, such as a value proportional with V _0. Then, the lock-up release circuit 109 outputs a lock-up off signal i to the lock-up control circuit 102 when the speed difference exceeds the predetermined value ΔV, whereby the lock-up control circuit 102 causes the lock-up control circuit 102 to map as shown in FIG. Irrespective of the determination result based on, the control signal d is output to the fourth solenoid 74 to release the lockup, and the lockup clutch 17 is released. In that case, the lock-up cancellation circuit 109 sets a lock-up time t (= α ·, α: constant) proportional to the speed decrease rate from the vehicle speed change detection circuit 110, and the off time is set only during this time t. It outputs the signal i.

Therefore, as shown in FIG. 5, during operation of the constant speed traveling device 105, the actual vehicle speed V decreases due to entry into an uphill road, etc., and there is a speed difference exceeding a predetermined value ΔV from the set vehicle speed V _0. When this occurs, the lockup clutch 17 is switched from on to off by inputting the speed decrease signal h from the constant speed traveling device 105 to the lockup release circuit 109 of the control circuit 100. In that case, As indicated by arrow X,
When the vehicle speed decreases at a large speed decrease rate x due to a large grade on the uphill road, etc., a long time tx (=
During the time of α · x), the lock-up clutch 17 is turned off, and as shown by the arrow Y, when the speed decrease rate y is small because the slope of the uphill road is relatively small, the lock-up clutch 17 remains for a relatively short time. It will be turned off only during ty (= α · y). This allows the lockup clutch
When the vehicle is running on a steep uphill road that requires a long time to return the actual vehicle speed V to the set vehicle speed V ₀ by turning off 17 to obtain the torque increasing effect of the torque converter, the off time tx also becomes long, and the lockup occurs. When the clutch 17 is turned on, the actual vehicle speed V is returned so as to substantially match the set vehicle speed V _0, and the lockup clutch is turned off to set the vehicle speed V ₀ in a relatively short time. In the case of a gentle uphill road that returns, the off time ty is correspondingly shortened, and it is prevented that the off state is continued unnecessarily after returning to the set vehicle speed V ₀ . In this way, when the vehicle speed decreases during climbing, etc., the torque converter can increase the torque, and the vehicle speed can be smoothly returned to the set vehicle speed. Even if the time required for the recovery of changes, the lockup is always released for the necessary time.

The control circuit 100 that performs the above-described control can be configured by, for example, a microcomputer,
In that case, the control circuit 100 operates according to the flowcharts shown in FIG. Next, this operation will be described.

Main Control First, the flowchart of the main control shown in FIG. 6 will be described. The control circuit first initializes various states in step A1, and then determines in step A2 whether or not the constant speed traveling device is operating. judge. Then, during normal running when the constant speed running device is not operating,
The range set by the shift lever is read at A3, and if it is set to one range, steps A4 to A5 to A9 are executed to release the lockup, and the engine speed is changed when shifting down to the 1st speed. After confirming by calculation whether or not the vehicle overruns, shifts to the second speed when the vehicle overruns, and to the first speed when the vehicle does not overrun. If it is set to 2 ranges,
Steps A4, A10, A11, A
Perform step 12, release the lockup, and then shift to the 2nd speed.

Further, when the range other than the 1st range and the 2nd range, that is, the D range is set, the steps A10 to A13 to A15 are executed to perform the upshift control, the downshift control and the lockup control described later.

On the other hand, when the constant speed traveling device is operating,
Perform lockup control during constant speed running from A2 according to steps A16 to A20. That is, the vehicle speed V is read by the signal from the vehicle speed sensor in steps A16 and A17, and
The rate of decrease in the vehicle speed, that is, the rate of decrease in speed is calculated, and in step A18, the set vehicle speed V ₀ is read by a signal from the constant speed traveling device. Then, in step A19, the set vehicle speed V ₀ is compared with the vehicle speed V, and when the actual vehicle speed falls below a predetermined value, in step A20, the lock-up off time t (= α which is proportional to the speed reduction rate).・) Is set, and this is set in the lockup release timer provided in the control circuit.

Shift-up control On the other hand, in the shift-up control of step A13 in the main control, as shown in FIG. 7, first, in step B1, it is confirmed whether or not the automatic transmission is in the fourth speed state,
When it is in the 4th speed, it is impossible to shift up, so the control ends. If the gear is not in the 4th speed, step B2
While reading the current throttle opening according to ~ B5, the set turbine speed Tmap corresponding to the read throttle opening is read from the preset upshift map, and the actual turbine speed T is read, Compare with the above set turbine speed Tmap. Here, the shift-up map stores the set turbine speed Tmap corresponding to each throttle opening as a shift-up line Mu as shown in FIG.
Mu corresponds to the boundary line X between the shift-up zone and the hold zone shown in FIG. When the actual turbine rotation speed T is higher than the set turbine rotation speed Tmap, that is, when the operation range is in the shift up zone shown in FIG. 4 or FIG. 8 and the shift up flag F1 is “0”, According to steps B6 to B8 from B5, the above-mentioned flag F1 is set to "1", and the shift speed is shifted up by one gear. The shift-up flag F1 indicates that the shift-up control is performed when it is "1". Therefore, when the flag F1 has already been set to "1" in step B6, the shift-up should be performed again. End control without Also, in step B5 above, the actual turbine speed T
When it is determined that is smaller than the set turbine speed Tmap, follow steps B9 to B11 and set turbine speed Tma
By multiplying p by 0.8, a new shift-up line Mu ′ shown by a broken line in FIG. 8 is set. Then, only when the actual turbine speed T is smaller than the new set turbine speed Tmap corresponding to the line Mu ′, the shift-up flag F1 is reset to “0” to prepare for the next shift-up control. When the turbine rotation speed T is higher than the new set turbine rotation speed Tmap, the control is terminated and shift down control is performed. In the control by steps B9 to B11, gear shifting is performed complicatedly when the turbine speed T is on the upshift line Mu by forming a hysteresis zone. This is to prevent so-called chattering.

Shift-down control The shift-down control in step A14 of FIG. 6 is executed as follows according to the flowchart of FIG.

First, in step C1, it is confirmed that the automatic transmission is not in the first speed, that is, in a gear that allows downshifting, and then downshift control is performed in accordance with step C2 and the subsequent steps. That is, according to steps C2 to C5, the actual throttle opening is read, and the set turbine speed Tm corresponding to the throttle opening at that time is selected from the shift down line Md set in the shift down map as shown in FIG.
Read ap and compare this with the actual turbine speed T. Here, the shift down line Md corresponds to the boundary line Y between the hold zone and the shift down zone shown in FIG. When the actual turbine rotation speed T is smaller than the set turbine rotation speed Tmap, that is, the operating region is the fourth
When in the shift-down zone shown in FIG. 10 or FIG. 10, according to steps C6 to C8, confirm that the shift-down flag F2 is reset to “0” and set the flag F2 to “1”.
Set to and then shift down one gear. Also in this case, if the flag F2 is already set to "1" in step C6, the control is ended. Further, in step C5, the actual turbine speed T is set to the set turbine speed Tm.
When it is larger than ap, according to steps C9 to C11, the set turbine speed Tmap is divided by 0.8 to form a new shift down line Md ′ as shown by a broken line in FIG. New set speed Tm corresponding to this line Md '
Compare with ap. Then, only when T> Tmap, the downshift flag F2 is reset to "0" to prepare for the next downshift.

Lockup Control Furthermore, the lockup control of step A15 in the main control of FIG. 6 is executed according to the flowchart shown in FIG.

First, in step D1, it is determined whether or not the lockup release timer is set. That is, whether or not the lockup release timer is set in step A20 of the chart in FIG. 6 because the speed has dropped below a predetermined value when approaching an uphill road while the constant speed traveling device is operating. If it is set, the flow advances to step D6 to output an off signal for releasing the lockup, and the flow ends. When the lockup release timer is not set, the throttle opening is read according to steps D2 to D5, and the throttle opening at that time is opened from the lockup release line Moff set in the lockup map as shown in Fig. 12. The set turbine rotation speed Tmap corresponding to the degree is read, and this is compared with the actual turbine rotation speed T. When the actual turbine rotation speed T is smaller than the set turbine rotation speed Tmap, that is, when it is in the lockup cancellation zone shown in FIG. 12, the lockup is canceled in step D6.

The actual turbine speed T is the above lock-up release line Moff
If it is larger than the set turbine speed Tmap corresponding to the above, in steps D7 and D8, set a hysteresis zone of a predetermined width on the high turbine speed side of the lockup release line Moff as shown by the broken line in FIG. Read the set turbine speed Tmap corresponding to the lockup operating line Mon
This set turbine speed Tmap and the actual turbine speed T
Compare with. Then, when T> Tmap, the lockup operation is controlled in step D9.

In this way, when it is determined in step D1 that the lockup release timer is set,
Regardless of the state of the map shown in FIG. 12, the process immediately proceeds to step D6 to release the lockup. As a result, when the constant speed traveling device is operated, a difference exceeding the predetermined value ΔV occurs between the actual vehicle speed V and the set vehicle speed V ₀ due to entry into an uphill road, etc., and the lockup is released when the lockup release timer is set. Is turned off, and the vehicle speed can be smoothly returned to the set value by the torque increasing action of the torque converter. Since the lockup release time t is set in step A20 of FIG. 6 in proportion to the speed decrease rate, it is long when the load is large, such as when driving steeply uphill, and when traveling on a relatively gentle uphill road. Shorter when the load is small. As a result, the lock-up release time t is always set to a time substantially corresponding to the time required to return the actual vehicle speed V to the set vehicle speed V ₀ , and when the actual vehicle speed is substantially returned to the set vehicle speed, the lock-up clutch is restored again. Since it is returned to the operating state, the lock-up off state does not continue even after returning to the set vehicle speed, and it is possible to prevent deterioration of fuel consumption.

(Effects of the Invention) As described above, according to the present invention, the actual vehicle speed is set by entering an uphill road or the like when the vehicle is traveling with the constant speed traveling device operating and the lockup activated (ON). When the vehicle speed is reduced by more than a predetermined width, the lock-up means is prohibited from operating for a predetermined time set according to the rate of change of the vehicle speed at that time.
When the vehicle speed decreases with a large speed decrease rate due to a large grade on the uphill road, the lockup device is prohibited from operating for a long period of time proportional to this, and the torque increase effect of the torque converter promptly increases the actual vehicle speed. Can be returned to the set vehicle speed.

Further, when the slope of the uphill road is relatively gentle, the time period for prohibiting the operation of the lockup means is shortened to prevent the lockup prohibition state from being unnecessarily continued after returning to the set vehicle speed. be able to. Further, the power transmission action of the torque converter through the fluid rarely causes a shock when the lockup clutch is turned on / off, and the vehicle speed can be smoothly returned.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a lockup device for an automatic transmission according to the present invention, and FIG. 2 is a structure and hydraulic pressure of a mechanical portion of an automatic transmission incorporating a lockup control device according to an embodiment of the present invention. FIG. 3 is an explanatory diagram showing a control circuit, FIG. 3 is an electric control circuit diagram of the automatic transmission, FIG. 4 is a characteristic diagram showing control characteristics by the electric control circuit, and FIG. 5 is a constant diagram used in the present invention. Graphs showing the relationship between the action of the high-speed traveling device and the action of lockup, Figs.
Flow charts showing shift-down and lock-up operations, and FIGS. 8, 10, and 12 are explanatory diagrams showing maps used for control of shift-up, shift-down, and lock-up, respectively. 1 …… Automatic transmission, 2 …… Engine 10 …… Torque converter 17 …… Lockup clutch 20,40 …… Shift gear mechanism 101 …… Shift control circuit 102 …… Lockup control circuit 105 …… Constant speed traveling device 109 …… Lockup release circuit 110 …… Vehicle speed change detection circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seiji Yashiki 3-3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (56) Reference JP-A-57-121713 (JP, A)

Claims (1)

[Claims] 1. A torque converter connected to an output shaft of an engine, a speed change gear mechanism connected to an output shaft of the torque converter, and a power transmission path connecting and disconnecting an input shaft and an output shaft of the torque converter. Lockup means for switching, electromagnetic means for controlling the supply of the pressure fluid supplied to the lockup means for operating the lockup means, a speed sensor for detecting the speed of the power transmission system, and a large load of the engine. Input signal from the engine load sensor for detecting the level and the output signals from the speed sensor and the engine load sensor, and compares these two output signals with a preset lock-up control line to generate a lock-up actuation signal. Lock-up determination means for receiving the lock-up operation signal from the lock-up determination means, and based on the operation signal, the electromagnetic hand In a lockup control device for an automatic transmission, which includes a lockup control means for driving and controlling the operation of the lockup means, a vehicle speed sensor and an engine output are controlled by receiving a set vehicle speed input from the outside. When the actual vehicle speed detected by the vehicle speed sensor during the operation of the constant-speed traveling device that holds the vehicle speed at approximately the set vehicle speed falls below the set vehicle speed by more than a predetermined width,
An automatic transmission characterized by comprising lock-up releasing means for issuing a lock-up prohibiting signal to the lock-up control means only for a predetermined time set according to the rate of change of the vehicle speed at that time. Lockup control device.