JPH05209676A - Control device for automatic transmission - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a shift shock and reduce the mechanical resistance when a one-way clutch runs idly in an automatic transmission arranged with a friction element and the one-way clutch in series. CONSTITUTION:In an automatic transmission AT arranged with the first clutch C1 and a one-way clutch 11 in series on a power transmitting member 10 from an input shaft 1 to a small sun gear 4, the first-to-second shift line and the first clutch switching line located on the higher vehicle speed side than the shift line are set on a shift map. At the time of an automatic cruise in the second speed region, the first clutch C1 is turned on at the lower vehicle speed side than the first clutch switching line, and it is turned off at the higher vehicle speed side. At the time of a first-to-second speed shift, the occurrence of a shift shock is prevented by the action of the one-way clutch 11. During a normal second-speed travel, the mechanical resistance of the one-way clutch 11 and the first clutch C1 is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an automatic transmission in which a friction element and a one-way clutch are arranged in series in a power transmission path of a speed change mechanism.

[0002]

2. Description of the Related Art Generally, an automatic transmission for an automobile is provided with a speed change gear mechanism including a planetary gear system including a sun gear, a ring gear, a pinion gear, a carrier, etc., and the speed change gear mechanism has a predetermined power transmission path. The power transmission path is switched by connecting or disconnecting or fixing a predetermined gear or carrier to change the gear ratio.
It is designed to switch between (reduction ratio, torque ratio). Therefore, the speed change gear mechanism includes a hydraulic clutch that engages (on) or releases (off) a predetermined power transmission path, or a hydraulic brake that fixes (on) or releases (off) a predetermined gear or carrier. Various friction elements such as A hydraulic control mechanism is provided to operate each of these friction elements, and the hydraulic control mechanism switches the on / off state of each friction element to perform a gear shift operation.

In an electronically controlled automatic transmission, a control unit equipped with a microcomputer controls a hydraulic mechanism via various solenoid valves in accordance with a shift map having throttle opening and vehicle speed as parameters. This allows the gear ratio to be switched. For example, in the case of an automatic transmission with two forward gears, a shift line of first speed → second speed (shift up line) and a shift line of second speed → first speed (shift down line) are set in the shift map. When the operating state reaches a state corresponding to such a shift line, the shift operation is performed.

Specifically, for example, when the first friction element is turned on while the second friction element is turned off, the gear ratio is large 1
In the speed change gear mechanism in which a high speed is obtained and the second friction element is turned on while the first friction element is turned off and the second gear element is turned on, the second speed having a small gear ratio is obtained at the time of shifting from the first speed to the second speed. , The first friction element is turned off while the second friction element is turned on. However, in this case, if the timing of turning off the first friction element is too early, both friction elements are temporarily turned off, and torque is not output to the drive wheel side during this time. On the other hand, if the timing of turning off the first friction element is too late, both friction elements are temporarily turned on, and during this time, there is a problem that a gear change shock occurs due to a sudden change in the gear ratio.

Therefore, in order to prevent such a torque non-transmission state or shift shock from occurring, an automatic transmission has been proposed in which a one-way clutch is provided in a power transmission path so as to be in series with a friction element. (For example,
(See Japanese Patent Laid-Open No. 61-109941). Here, the one-way clutch is locked in a certain rotation direction and transmits torque, but is free in the opposite rotation direction and does not transmit torque. For example, as shown in FIG. 6, when the clutch 100 is engaged, when the input shaft 101 rotates relative to the output shaft 102 in the X direction, the one-way clutch 103 is in a locked state, and the input shaft 101 changes from the output shaft 102 to the output shaft 102. Although torque is transmitted, when the output shaft 102 rotates at a higher speed in the X direction than the input shaft 101, the one-way clutch 103
Becomes free, and substantial torque is not transmitted between the input shaft 101 and the output shaft 102.

[0006] For example, in the case of the above-described two-stage forward automatic transmission, a one-way clutch is arranged in series with the first friction element, the first friction element is turned on at the first speed, and the one-way clutch is locked at this time. Then, the torque is output from the input side to the output side at the first speed gear ratio. When shifting from the first speed to the second speed, the second friction element is turned on with the first friction element held in the on state, and the one-way clutch is automatically released when the second friction element is turned on. The automatic transmission is automatically set to the second speed state. When the second friction element is turned off, the automatic transmission automatically enters the first speed state. Therefore, the torque non-transmission state or the shift shock is prevented from occurring.

[0007]

However, generally, in a one-way clutch, mechanical resistance is generated even during idling due to the contact between the roller and the inner race or the outer race. The mechanical resistance becomes larger as the rotational speed difference between the input side and the output side of the one-way clutch increases. Therefore, there is a problem that the fuel consumption performance is deteriorated by the power loss due to the mechanical resistance. The present invention has been made to solve the above-mentioned conventional problems, and in an automatic transmission in which a friction element and a one-way clutch are arranged in series in a power transmission path of a speed change mechanism, a shift shock is generated. It is an object of the present invention to provide an automatic transmission capable of reducing power loss due to mechanical resistance of a one-way clutch and improving fuel efficiency while preventing the above.

[0008]

To achieve the above object, a first aspect of the present invention is such that a friction element and a one-way clutch are arranged in series in a power transmission path of a speed change mechanism, while a predetermined speed change line is used for division. A control device for an automatic transmission provided with shift control means for controlling a speed change mechanism so that a friction element is engaged and a one-way clutch is locked in one of the operated regions and the one-way clutch is unlocked in the other. In, in the operating region of the one-way clutch is in the unlocked state, the friction element switching line is set to be separated from the shift line,
Friction element control means is provided for engaging the friction element in the operating area between the friction element switching line and the speed change line, and releasing the friction element in the operating area on the side opposite to the speed change line from the friction element switching line. There is provided a control device for an automatic transmission characterized by:

According to a second aspect of the invention, in the control device for an automatic transmission according to the first aspect, a constant speed traveling device is provided and only when the constant speed traveling device is performing constant speed traveling. There is provided a control device for an automatic transmission, characterized in that the friction element control means is adapted to perform the engagement / disengagement of the friction element according to a friction element switching line.

[0010]

EXAMPLES Examples of the present invention will be specifically described below.
As shown in FIG. 1, the automatic transmission AT is configured to shift the torque of an input shaft 1 (engine side) by a two-step forward speed change gear mechanism 2 and output it to an output shaft 3 (driving wheel side). ing.
Although not shown, the automatic transmission AT is provided with a torque converter for increasing torque, a forward / reverse switching mechanism, and the like in addition to the speed change gear mechanism 2. The speed change gear mechanism 2 is an ordinary planetary gear system. The speed change gear mechanism 2 has a relatively small diameter small sun gear 4 loosely fitted to the input shaft 1 and a front side of the small sun gear 4 (left side in FIG. 1). A large sun gear 5 having a relatively large diameter loosely fitted to the input shaft 1, a plurality of short pinion gears 6 (only one shown) meshing with the small sun gear 4, and a rear portion.
(The right side in FIG. 1) meshes with the short pinion gear 6 and the front part meshes with the large sun gear 5 with the long pinion gear 7.
Further, a ring gear 9 that is meshed with the long pinion gear 7 and that is connected to the output shaft 3 is provided, and a carrier 8 that rotatably (rotatably) supports the short pinion gear 6 and the long pinion gear 7. In the speed change gear mechanism 2, the small sun gear 4 or the carrier 8 serves as a torque input section according to the gear stage, while the ring gear 9 serves as a torque output section at any gear stage.

In order to switch the torque transmission path (power transmission path) in the speed change gear mechanism 2, that is, in order to switch the range or the shift speed, a plurality of friction elements are used.
(Clutch C1, C2 and brake B1) are provided. Specifically, the first power transmission member 10, which is a power transmission path between the output shaft 1 and the small sun gear 4, is attached to the first power transmission member 10.
The clutch C1 and the one-way clutch 11 are provided in series. In the one-way clutch 11, the outer member 10a or the intermediate member 10b of the first power transmission member 10 is faster than the inner member 10c in the Y direction (forward direction) when the first clutch C1 is engaged (turned on). When it is about to rotate, the outer member 10a or the intermediate member 10b (the input shaft 1) rotationally drives the inner member 10c (the small sun gear 4). On the other hand, when the inner member 10c rotates in the Y direction at a higher speed than the intermediate member 10b, the one-way clutch 11 is in a free state (unlocked state), and the intermediate member 10b (input shaft 1) and the inner member 10c (small sun gear 4). A substantial torque is not transmitted between and. Of course, when the first clutch C1 is released (OFF), substantial torque transmission is not performed between the input shaft 1 and the small sun gear 4 regardless of the operating state. A second clutch C2 is provided on the second power transmission member 13 which is a power transmission path between the output shaft 1 and the carrier 8. Further, a brake B1 for fixing (on) or releasing (off) the large sun gear 5 is provided between the fixed member 14 connected to the large sun gear 5 and the transmission case 12 (fixed portion). ..

By changing the on / off patterns of both the clutches C1 and C2 and the brake B1,
Various ranges and gears as shown in Table 1 can be obtained. Hereinafter, with reference to Table 1, the torque transmission path and the shift characteristics in each range or shift stage will be described. The friction elements C1, C2, B1 are turned on / off by a hydraulic control mechanism F (see FIG. 2) controlled by a control unit CU, as described later.

[0013]

[Table 1]

(1) N range ... Both clutches C1 and C2 and brake B1 are turned off. The one-way clutch 11 has no particular effect. In this case, the torque of the input shaft 1 is not transmitted to the output shaft 3. (2) First speed in the D range ... The first and second clutches C1 and C2 are turned on, and the brake B1 is turned off. The one-way clutch 11 is locked. In this case, the small sun gear 4 and the carrier 8 cannot be differentiated, so that the transmission gear mechanism 2 is directly connected. Therefore, the gear ratio (torque ratio) is 1.

(3) D range second speed standard ... Both clutches C1 and C2 and brake B1 are turned on. The one-way clutch 11 is in a free state. In this case, the torque of the input shaft 1 is equal to the torque of the second power transmission member 13
And is input to the carrier 8 via the second clutch C2,
The torque of the carrier 8 is sequentially output to the output shaft 3 via the long pinion gear 7 and the ring gear 9. Since the large sun gear 5 is fixed by the brake B1, the long pinion gear 7 revolves around the large sun gear 5 while rotating. Therefore, the rotational speed of the ring gear 9 becomes higher than the rotational speed of the carrier 8 (rotational speed of the input shaft 1) by the amount of rotation of the long pinion gear 7, and the transmission gear mechanism 2 is in the overdrive (acceleration) state. That is, the gear ratio becomes smaller than 1.

(4) D range second speed economy ... The first clutch C1 is turned off, and the second clutch C2 and the brake B1 are turned on. The one-way clutch 11 is in a free state. In this case, the torque transmission path and the speed change characteristic are basically the same as those in the above-mentioned D range second speed standard. However, as will be described later, the mechanical resistance of the one-way clutch 11 to the first clutch C1 is reduced, so that the fuel efficiency performance is improved.

Hereinafter, each friction element C1, C2, B1 is turned on.
The hydraulic control mechanism F for turning off will be described. As shown in FIG. 2, the hydraulic control mechanism F controls the oil discharged from the oil pump 15 to a predetermined hydraulic pressure by the line pressure control means L.
(Line pressure) is adjusted, and this oil or line pressure is supplied to each part through the main hydraulic pressure supply passage 16. The line pressure is controlled by the control unit CU.
Is controlled according to the driving state. The oil or line pressure in the main hydraulic pressure supply passage 16 is respectively the first to third branched hydraulic pressure supply passages 17 to
It is adapted to be supplied to each friction element C1, C2, B1 through 19. Here, in the first to third branch hydraulic pressure supply passages 17 to 19, the first to third opening and closing of the respective passages 17 to 19 are performed according to a signal from the control unit CU.
The valve mechanisms V1 to V3 are interposed. Here, the control unit CU includes a vehicle speed detected by the vehicle speed sensor 21, a throttle opening detected by the throttle opening sensor 22, and an auto speed controller provided for a constant speed traveling device (auto cruise device) not shown. Predetermined control is performed by using an auto cruise set signal detected by the cruise set switch 23 as control information. The assembly including the control unit CU and the hydraulic control mechanism F is a comprehensive control of the automatic transmission AT including the "shift control means" and the "friction element control means" described in claims 1 and 2. It is a device.

As shown in FIG. 3, the first valve mechanism V1
Is composed of a first control valve 26 and a second control valve 27. In the housing 31 of the first control valve 26, the first to third land portions 32 are provided.
A valve spool 32 having a to 32c is fitted. The valve spool 32 is always turned off by a return spring 33 whose one end is locked to the fixed portion 34.
It is biased (to the left in FIG. 3). The first control valve 26 has a line pressure input port 35 that communicates with the upstream portion 17a of the first branch hydraulic pressure supply passage 17 and a line pressure output port 36 that communicates with the downstream portion 17b of the first branch hydraulic pressure supply passage 17. A drain port 38 and a pilot pressure introducing port 39 communicating with the downstream pilot pressure oil passage 40.

When no hydraulic pressure (pilot pressure) is applied to the pilot pressure introducing port 39, the valve spool 32 is urged by the return spring 33.
Is in the off position (FIG. 3 shows this state), and at this time, the line pressure input port 3 is moved by the first land portion 32a.
While 5 is closed, the line pressure output port 36 and the drain port 38 are opened, the hydraulic pressure in the first clutch C1 is released from the drain port 38, and the first clutch C1 is turned off. When the pilot pressure is applied to the pilot pressure introducing port 39, the return spring 33
Against the biasing force of the valve spool 32 in the ON direction (see FIG.
, And the drain port 38 is closed by the second land portion 32b, while the line pressure input port 35
And the line pressure output port 36 are opened, and the line pressure is supplied to the first clutch C1 through the upstream portion 17a and the downstream portion 17b of the first branch hydraulic pressure supply passage 17, and the first clutch C
1 is turned on.

A valve spool 42 having first to third land portions 42a to 42c is fitted in the housing 41 of the second control valve 27. The valve spool 42 is constantly urged in the off direction (rightward in FIG. 3) by the return spring 43. An electromagnetic drive unit 44 is provided at the end of the valve spool 42 opposite to the return spring 43 side.
4 is biased in the ON direction by magnetic force when the electromagnetic solenoid 45 is energized (ON).
The energization of the electromagnetic solenoid 45 is controlled by the control unit CU. The second control valve 27 has a pilot pressure input port 46 communicating with the upstream pilot pressure oil passage 47 branched from the first branch hydraulic pressure supply passage 17, and a pilot pressure output communicating with the downstream pilot pressure oil passage 40. Port 49
And a pilot pressure release port 51 that communicates with a pilot pressure release passage 52 that branches from the downstream pilot pressure oil passage 40, and a drain port 53.
An orifice 48 is provided in the upstream pilot pressure oil passage 47.
Is installed.

When the electromagnetic solenoid 45 is not energized (OFF), the valve spool 42 is in the OFF position due to the urging force of the return spring 43 (see FIG. 3).
Indicates this state), and at this time, the third land portion 42c
Due to this, the pilot pressure input port 46 and the pilot pressure output port 49 are closed, while the pilot pressure release port 51 and the drain port 53 are opened. At this time, the pilot pressure is not supplied to the pilot pressure introducing port 39 of the first control valve 26, so that the first clutch C1 is turned off. On the other hand, when the electromagnetic solenoid 45 is energized (ON), the valve spool 42 is displaced in the ON direction against the urging force of the return spring 43, and the pilot pressure release port 51 and the drain port 53 are separated by the first land portion 42a. While pilot pressure input port 46 and pilot pressure output port 49 are opened. At this time, the pilot pressure is supplied to the pilot pressure introducing port 39 of the first control valve 26, so that the first clutch C1 is turned on. Although not shown, the second and third valve mechanisms V
2 and V3 also have the same configuration as the first valve mechanism V1.

Hereinafter, the shift operation or control operation of the automatic transmission AT will be described with reference to FIGS. Basically, the automatic transmission AT is automatically controlled by a control unit CU having control information such as a vehicle speed, a throttle opening degree, an auto cruise set signal and the like according to an operating state. However, the range (N,
The selection of D ...) is manually performed by the driver through a select lever (not shown). Then, depending on the driver, N range (neutral range)
Is selected, the control unit CU
As a result, the electromagnetic solenoids 45 of the first to third valve mechanisms V1 to V3 are all turned off, and the first and second clutches C1, C
2 and the hydraulic pressure of the brake B1 are released. At this time, the first and second clutches C1 and C2 and the brake B1 are all turned off, and torque is not transmitted from the input shaft 1 to the output shaft 3 (see Table 1).

When the driver selects the D range (drive range), the control unit CU controls the vehicle speed and throttle opening as shown in FIG.
The gear position (first speed, second speed standard, second speed economy) is automatically switched according to a speed change map using (engine load) as a parameter. In the shift map shown in FIG. 4, a shift line H ₁ is set that divides the operating range at 1st speed (1st speed range) from the operating range at 2nd speed (2nd speed range).
The area A1 on the low vehicle speed side (high load side) of the shift line H ₁ is 1
It is in the high speed range and is on the higher vehicle speed side (lower load side) than the shift line H _1.
The areas A2 and A3 of 2 are the second speed areas. And 2
In the speed range, the first clutch switching line H ₂ is set at a position slightly separated from the shift line H ₁ on the high vehicle speed side (low load side), and the shift line H ₁ and the first clutch switching line H _{2 are set.}
The area A2 between and is the second speed standard area,
Region A3 of the high vehicle speed side than the clutch-switching line H ₂ (the low load side) is the second speed Ekonomi region. The first clutch switching line H ₂ corresponds to the “friction element switching line” described in claim 1.

When the operating state is within the first speed range A1, the electromagnetic solenoids 45 of the first and second valve mechanisms V1 and V2 are turned on and the first and second clutches C1 and C2 are turned on. , The electromagnetic solenoid 4 of the third valve mechanism V3
5 is turned off and the brake B1 is turned off. At this time, as described above, the gear ratio of the transmission gear mechanism 2 becomes 1, and the one-way clutch 11 is in the locked state (Table 1
reference).

When the operating condition is within the second speed standard range A2, all the electromagnetic solenoids 45 of the first to third valve mechanisms V1 to V3 are turned on, and the first and second clutches C1 and C2 and the brake B1 are turned on. To be done. At this time, as described above, the gear ratio of the transmission gear mechanism 2 becomes smaller than 1, and the one-way clutch 11 runs idle (Table 1
reference). In this case, since the first clutch C1 is turned on, the outer member 10a and the intermediate member 10b of the first power transmission member 10 have the same rotation speed as the input shaft 1 and Y in FIG.
Rotate in the direction (forward direction). On the other hand, the inner member 10c is
It is rotationally driven by the carrier 8 via the short pinio gear 6 and the small sun gear 4, and rotates in the Y direction at a higher speed than the input shaft 1. Therefore, the one-way clutch 11 idles, but as described above, some mechanical resistance is generated in the one-way clutch 11 in the idling state. In this case, the mechanical resistance increases in a substantially quadratic curve like a curve G _{1 in} FIG. 5 as the rotation speed difference (idling rotation speed) between the intermediate member 10b and the inner member 10c increases. .. Therefore, in the second speed standard mode, power loss occurs due to such mechanical resistance, and the fuel efficiency performance of the engine deteriorates.

When the operating condition is within the second speed economy area A3 and the auto cruise set signal is on, that is, during auto cruise (during constant speed traveling by the constant speed traveling device).
The electromagnetic solenoid 45 of the first valve mechanism V1 is turned off and the first clutch C1 is turned off.
The electromagnetic solenoids 45 of the valve mechanisms V2 and V3 are turned on, and the second clutch C2 and the brake B1 are turned on.
The power transmission characteristic or gear ratio in this case is basically 2
This is similar to the case of the fast standard mode. in this case,
Although the first clutch C1 is off, the opposing clutch plates of the first clutch C1 slightly frictionally engage with each other even when the first clutch C1 is off, and some mechanical resistance is generated in the first clutch C1. In this case, the mechanical resistance is the outer member 10
As the rotational speed difference (idling rotational speed) between the a and the intermediate member 10b increases, the rotational speed increases in a substantially quadratic curve like the curve G ₂ in FIG. In this case, the one-way clutch 11 is also idling. Therefore, the outer member 10a, the intermediate member 10b, and the inner member 10c rotate at different rotational speeds. At this time, in the one-way clutch 11, mechanical resistance corresponding to the idling rotation speed in the one-way clutch 11 is generated,
In the first clutch C1, mechanical resistance corresponding to the idling rotation speed in the first clutch C1 is generated. Therefore, this 2
Power loss also occurs in the fast economy mode, but as will be described below, the power loss in the 2-speed economy mode is significantly smaller than that in the 2-speed standard mode.

Here, for example, when the idling rotation speed between the outer member 10a and the inner member 10c is N, the idling rotation speed N ₁ of the one-way clutch 11 and the first clutch C1.
The sum (N ₁ + N ₂ ) of the idle rotation speeds N ₂ becomes equal to N. In this case, the mechanical resistance of the one-way clutch 11 and the first
The mechanical resistance of the clutch C1 becomes equal. For example, in FIG.
As shown in, when the idling rotation speed between the outer member 10a and the inner member 10c is N, the mechanical resistance becomes P in the second speed standard mode in which the first clutch C1 is turned on and only the one-way clutch 11 is idling.

On the other hand, in the second speed economy mode in which the first clutch C1 is turned off and the one-way clutch 11 and the first clutch C1 both run idle, the mechanical resistance of both the one-way clutch 11 and the first clutch C1 becomes Pa. At this time, the idling rotation speed of the one-way clutch 11 becomes N ₁ , and the idling rotation speed of the first clutch C1 becomes N ₂ . Here, it goes without saying that N ₁ + N ₂ = N.
Therefore, the total mechanical resistance of the first power transmission member 10 is 2
It becomes Pa. And as is clear from FIG. 5, this 2
The total mechanical resistance 2Pa in the fast economy mode is significantly smaller than the mechanical resistance P in the second speed standard mode, so that the power loss is significantly reduced and the fuel efficiency is improved.

During automatic cruise, when shifting from the first speed to the second speed (upshifting), normally, the vehicle enters the second speed standard area A2 from the first speed area A1 and then stays in the area A2 for a while. It will enter the second-speed economy area A3. Therefore, during the shift from the first speed to the second speed standard, the power transmission by the first power transmission member 10 is interrupted by the action of the one-way clutch 11 while the first clutch C1 is kept in the ON state. Therefore, the interruption of the power transmission by the first power transmission member 10 is caused by the brake B.
Corresponding to the 1 ON operation, it is automatically performed at an appropriate timing without being too early and without delay,
Gear shift shock does not occur. Needless to say, no shift shock occurs when shifting from the 2-speed standard mode to the 2-speed economy mode. Similarly, at the time of shifting from the 2nd speed standard mode to the 1st speed (downshift), the one-way clutch 11 operates in response to the OFF operation of the brake B1 while the first clutch C1 is maintained in the ON state. 1st automatically at the right time
Power transmission of the power transmission member 10 is started. Therefore, the occurrence of shift shock is effectively prevented.

On the other hand, when it is not during auto cruise,
First the first clutch C1 in accordance with the clutch-switching line H ₂
OFF operation, that is, the second speed economy mode is not performed. That is, when the second-speed economy mode is set, for example, as shown by a double-headed arrow Z in FIG. 5, when gear shifting is performed in response to a sudden change in throttle opening such as sudden depression or release of the accelerator pedal,
The time during which the operating condition remains in the second speed standard range A2 becomes extremely short. Therefore, when shifting from the 1st speed to the 2nd speed, it is almost the same as shifting from the 1st speed directly to the 2nd speed economy mode, and when shifting from the 2nd speed to the 1st speed,
This is because there is a possibility that the one-way clutch 11 will not be able to exert its effect, and a gear shift shock will occur, as in the case where the gear shifts from the second gear economy mode to the first gear directly. However, in this embodiment, 2
Since the fast economy mode is executed only during an auto cruise where a sudden change in the throttle opening does not occur, such a shift shock does not occur. Needless to say, the second speed economy mode may be executed even when the auto cruise is not being performed. As described above, according to the present embodiment, it is possible to reduce the mechanical resistance of the one-way clutch 11 to the first clutch C1 while preventing the occurrence of shift shock, and improve the fuel efficiency.

[0031]

According to the first aspect of the present invention, at the time of predetermined gear shifting, the power transmission of the power transmission path in which the friction element and the one-way clutch are arranged is automatically interrupted by the action of the one-way clutch. Since it is performed at an appropriate timing, the occurrence of shift shock is prevented. When the operating state reaches the friction element switching line after shifting, the friction element is released and both the one-way clutch and the friction element idle at low speed. Here, generally, in a one-way clutch or a friction element, the mechanical resistance increases in a substantially quadratic curve with an increase in the idling rotation speed. For this reason, the mechanical resistance in the one-way clutch or the friction element having a low idling rotation speed becomes very small, the power loss is reduced, and the fuel efficiency is improved.

According to the second invention, basically, the same operation and effect as those of the first invention can be obtained. Further, since the discontinuity of the friction element according to the friction element switching line is limited to the constant speed running, the friction element maintains the engaged state during the gear shift due to the sudden change of the engine load, and the one-way clutch and the friction element The power transmission of the power transmission path in which is arranged is interrupted by the action of the one-way clutch. Therefore, it is possible to more completely prevent the occurrence of shift shock.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an automatic transmission including a control device according to the present invention.

FIG. 2 is a schematic diagram of a hydraulic control mechanism of an automatic transmission.

FIG. 3 is a schematic view of a first valve mechanism.

FIG. 4 is a diagram showing a shift map.

FIG. 5 is a diagram showing characteristics of mechanical resistances of a one-way clutch and a first clutch with respect to idling rotation speed.

FIG. 6 is a schematic view of a one-way clutch and a clutch arranged in series.

[Explanation of symbols]

 AT ... Automatic transmission CU ... Control unit B1 ... Brake C1 ... First clutch C2 ... Second clutch F ... Hydraulic control mechanism 2 ... Transmission gear mechanism 10 ... First power transmission member 11 ... One way clutch 23 ... Auto cruise set switch

Claims (2)

[Claims] 1. A friction element and a one-way clutch are arranged in series in a power transmission path of a speed change mechanism, while the friction element is engaged and the one-way clutch is locked in one of operating regions divided by a predetermined speed change line. State, and on the other hand, in the control device for the automatic transmission provided with the shift control means for controlling the speed change mechanism so as to bring the one-way clutch into the unlocked state, in the operating range of the one-way clutch in the unlocked state, The friction element switching line is set so as to be separated from the speed change line, and the friction element is fastened in the operating region between the friction element switching line and the speed change line, while the operation on the side opposite to the speed change line from the friction element switching line is performed. A control device for an automatic transmission, characterized in that friction element control means for releasing a friction element is provided in a region. 2. The control device for an automatic transmission according to claim 1, wherein a constant speed traveling device is provided, and the friction element is provided only when constant speed traveling is performed by the constant speed traveling device. A control device for an automatic transmission, characterized in that the control means is adapted to perform the engagement / disengagement of the friction element according to a friction element switching line.