JPH0249428B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control device for an automatic transmission, and more particularly to control of an automatic transmission in which an auxiliary transmission is provided on the output side of a main transmission.

BACKGROUND OF THE INVENTION In order to improve driving performance, there is an automatic transmission that is equipped with an auxiliary transmission that can be manually switched between a high gear and a low gear. In such automatic transmissions, the auxiliary transmission is located on the output side of the main transmission that can automatically change gears, in order to reduce the number of changes required for automatic transmissions without an auxiliary transmission, which is advantageous in terms of manufacturing. It is often set up in

However, if the driver unnecessarily changes the operating position of the auxiliary transmission from the high gear position to the low gear position while driving at high speed, the engine rotation speed will exceed the allowable value (overrun), resulting in damage to the engine and tire slip. Danger may occur.

In the transmission disclosed in JP-A No. 56-73251, a manual transmission and an automatic transmission are connected in series, and when the manual transmission is in a low gear, that is, when the torque fluctuation of the engine is large, , the automatic transmission is prohibited from shifting to avoid excessive shift shock. Furthermore, in the transmission disclosed in JP-A No. 56-73252, a manual transmission and an automatic transmission are similarly connected in series, and downshifting of the automatic transmission is prohibited when the engine speed is above a predetermined value. This prevents the engine from overrunning. However, neither publication mentions manual transmission control to avoid engine overrun.

Purpose of the Invention An object of the present invention is to provide an automatic transmission in which an auxiliary transmission capable of manually changing gears is provided on the output side of a main transmission, in which the operation position of the auxiliary transmission changes from a high gear position to a low gear position. An object of the present invention is to provide a control device that prevents an engine from overrunning when switched to a stage position.

Means for Achieving the Object The control device of the present invention includes a main transmission that is connected to the output side of an engine and that is automatically switched to a plurality of gears based on a plurality of pieces of information including vehicle speed; An auxiliary transmission that is connected to the output shaft and can be manually switched between high and low gears, and a vehicle speed sensor that detects the output shaft rotational speed of the main transmission or an equivalent rotational speed to determine the vehicle speed. The invention is directed to an automatic transmission comprising: the main transmission being at the highest speed allowed in the low gear state of the sub-transmission and the sub-transmission being at the low gear; Provided with a prohibition means for prohibiting the auxiliary transmission from shifting to the low gear position even though the operating position of the auxiliary transmission is in the low gear position when the vehicle speed is equal to or higher than the maximum permissible rotational speed of the engine. There is.

Effects and Effects of the Invention Therefore, in the present invention, when an attempt is made to switch the sub-gear to a low gear, the gear of the main transmission is
If the auxiliary transmission is at the highest speed allowed for the low gear, and the auxiliary gear is switched to the lower gear for the main transmission, the engine speed will exceed the permissible rotation speed. If the vehicle speed is low, the auxiliary transmission is prohibited from actually switching to a low gear. Further, if the main transmission is not in the above-mentioned allowed highest speed, the main transmission is upshifted due to the increase in the output shaft rotational speed of the main transmission as the sub-transmission is switched to the lower speed.

Therefore, overrun of the engine is prevented, and dangers such as damage to the engine and tire slip, which are prone to overrun, can be avoided. In addition, when the main transmission upshifts when the sub-transmission is shifted to a lower gear, the increase in the gear ratio in the sub-transmission is made larger than the decrease in the gear ratio in the main transmission. , the running torque can be increased somewhat.

According to a preferred embodiment, the inhibiting means includes a solenoid valve that controls the supply of hydraulic medium to the high-speed friction engagement device and the low-speed friction engagement device of the auxiliary transmission, and a solenoid that controls the solenoid valve. It has valve control means.

According to yet another embodiment, the inhibiting means includes a switching valve that selectively guides the hydraulic medium to the high speed friction engagement device and the low speed friction engagement device of the auxiliary transmission;
A control pressure oil passage that guides the control pressure that holds the switching valve in the low gear position when the operating position of the sub-transmission is in the low gear position, and a control pressure oil passage that opens and closes in relation to the governor pressure related to vehicle speed. It has an on-off valve.

Example The present invention will be described with reference to the embodiments shown in the drawings.

FIG. 1 shows an automatic transmission and its control device, including an engine 10, a fluid torque converter 12,
A main transmission 14 and a sub-transmission 16 are provided in series in a power transmission path of the engine. The lock-up clutch 18 is provided in parallel with the fluid torque converter 12, and the main transmission 14 has first to fourth gears that are automatically switched depending on vehicle speed and throttle opening, and a sub-shift. Machine 16
has a high speed gear and a low gear that can be switched by manual operation. The shift position sensor 20 detects a shift position such as D (drive), N (neutral), or R (reverse) range selected by the driver, and the L/H position sensor 22 detects a shift position selected by the driver. The L (low gear) and H (high gear) of the auxiliary transmission 16 are detected, the throttle opening sensor 24 detects the intake throttle opening, and the pattern select switch 26 detects the economy selected by the driver. , power (acceleration driving)
The water temperature sensor 28 detects the engine cooling water temperature, and the brake switch 3
0 detects the depression of the foot brake, the vehicle speed sensor 32 detects the rotational speed of the output shaft 34 of the main transmission 14,
Therefore, the vehicle speed is detected. The CPU 36 operates the solenoid valves 42 and 42 of the main transmission control hydraulic circuit 38 and the sub-transmission control hydraulic circuit 40 based on input signals from these sensors and switches.
44, 46, 48, and an alarm device 50. The solenoid valves 42 and 44 are connected to the main transmission 14
The solenoid valve 46 is used to control the lockup clutch 18, and the solenoid valve 48 controls the high speed and low speed of the auxiliary transmission 16. used for

FIG. 2 is a flowchart of the speed change control routine. When the ignition switch is turned on (step 6)
0), a flag F indicating that the operating position of the sub-transmission 16 has changed from H (high gear) to L (low gear) is initialized (step 62), and in the main routine. The commanded gear position of the main transmission 14 is calculated (step 64). The designated gear position is set as a function of vehicle speed V, intake throttle opening degree θ, and the like. If there is no change in the operating position of the sub-transmission 16 from H to L (determination at step 68 is NO), the sub-transmission 1
Drive control of the sub-transmission solenoid valve 48 is performed based on the operating position of step 6 (step 86).
Next, drive control of the main transmission solenoid valves 42, 44, and 46 is performed based on the instructed gear position (step 88). When the operating position changes from H to L (determination at step 68 is YES), flag F is set (step 70), and since it is determined that F=1 (determination at step 66 is F=1), the vehicle speed V is read (step 72), and V is compared with a predetermined value Vc (step 74). Vc is main transmission 1
4 is defined as the minimum vehicle speed at which the engine speed exceeds the permissible rotational speed if the auxiliary transmission 16 is at a low speed even though the auxiliary transmission 16 is at the highest permitted speed. If it is VVc, that is, if the vehicle speed is such that the engine will overrun if the auxiliary transmission 16 shifts to a low gear, an instruction to inhibit the auxiliary transmission 16 from shifting to a low gear is issued (step 76), and the warning device 50 is activated ( Step 78). If the driver notices the warning and returns the operating position from L to H (YES in step 80), there will be no problem, but even if the driver does not return the operating position to H, a low gear prohibition instruction will be issued. Therefore, the auxiliary transmission 16 does not shift to a low gear even during drive control of the auxiliary transmission solenoid valve (step 86). If V<Vc (determination in step 74 is V<Vc), sub-transmission 1
Since there is no risk of an engine overrun even if gear 6 shifts to a low gear, an instruction to permit the sub-transmission 16 to shift to a low gear is issued (step 82), flag F is reset (step 100), and the sub-transmission 16 is The drive control of the solenoid valve (step 86) is performed according to the actual operating position.

FIG. 3 shows a hydraulic control device that prohibits the sub-transmission 16 from shifting to a low gear using a spool valve.

The L/H switching valve 94 has ports 98 and 100 connected to the line pressure oil passage 96, and a drain 10.
2, 104, port 108 connected to the high speed friction engagement device 106 of the auxiliary transmission 16, port 1 connected to the low speed friction engagement device 110
12, and a control port 114. The control pressure oil passage 116 is connected to the control port 114, and the introduction of line pressure to the control pressure oil passage 116 is controlled by the aforementioned solenoid valve 48. That is, during the period when the line pressure Pl reaches the control port 114, the spool of the L/H switching valve 94 is in the low speed position, and the ports 108 and 112 are connected to the drain 102 and the port 100, respectively, and the friction coefficient for the low speed is connected. The coupling device 110 is in the engaged state. During the period in which the line pressure Pl has not reached the control port 114, the L/H switching valve 94 is in the high speed position, and the ports 108 and 112 are in the high-speed position.
8. It is connected to the drain 104, and the high-speed stage friction engagement device 106 is in an engaged state.

The L prohibition control valve 118 as a spool valve is
Port 12 provided in the middle of control pressure oil passage 116
0,122, control port 124 supplied with governor pressure Pgo related to vehicle speed, drain 126,12
8. Port 120, port 122 and drain 126
It has a spool 130 that controls the connection between the spool 130 and a spring 132 that biases the spool 130.

The oil pressure switch 134 is turned on when the oil pressure in the control port 114 exceeds a predetermined value, and this on signal is sent to the AND circuit 138 via the inverter 136. An L signal indicating that the operating position of the sub-transmission 16 is L is sent to the other input terminal of the AND circuit 138. Alarm device 140 is controlled by the output of AND circuit 138.

The operation of the device shown in FIG. 3 will be explained.

When the vehicle speed V is less than Vc, since Pgo is small in the L prohibition control valve 118, the spool 1
30 is moved toward control port 124 by spring 132, and ports 120 and 122 are connected. The solenoid valve 48 discharges the line pressure Pl from the control pressure oil passage 116 or introduces it into the control pressure oil passage 116 according to the operation position H or L, so when the solenoid valve 48 is in the H position, the high speed friction engagement device 106 is engaged. When the gear position is L, the low speed friction engagement device 110 is engaged.

When the vehicle speed V is higher than Vc, Pgo is large in the L prohibition control valve 118, so the spool 1
30 moves toward spring 132 and ports 120,
122 is disconnected. Therefore, even if the operating position is at L, the line pressure Pl does not reach the control port 114 of the L/H switching valve 94, and the high-speed friction engagement device 106 remains engaged regardless of the operating position. . When the hydraulic switch 134 is off (logical value o) because the line pressure Pl does not come to the control port 114 even though the operating position is L and the L signal is generated, the output of the AND circuit 138 is The logical value becomes 1, and the alarm device 140 issues an alarm.

Although the present invention has been described with reference to embodiments, it will be obvious that various embodiments are possible without departing from the scope of the present invention.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an automatic transmission and its control device, Fig. 2 is a flowchart of a shift control routine, and Fig. 3 is a circuit diagram of a hydraulic control device that uses a spool valve to inhibit a low gear shift of an auxiliary transmission. It is. 14...Main transmission, 16...Sub-transmission, 22...L・
H position sensor, 32...Vehicle speed sensor, 36...
CPU, 118...L prohibition control valve.

Claims (1)

[Scope of Claims] 1. A main transmission connected to the output side of the engine and automatically switching to a plurality of gears based on a plurality of pieces of information including vehicle speed; An automatic transmission equipped with an auxiliary transmission that can be manually switched between high and low gears, and a vehicle speed sensor that detects the output shaft rotational speed of the main transmission or an equivalent rotational speed to determine the vehicle speed. In the control device of the engine, the vehicle speed is higher than the vehicle speed that is the maximum allowable rotation speed of the engine when the main transmission is in the highest speed allowed with the auxiliary transmission in the low speed state and the auxiliary transmission is in the low speed. A control device for an automatic transmission, characterized in that the automatic transmission control device is provided with a prohibition means for prohibiting the auxiliary transmission from shifting to the low gear position even though the operating position of the auxiliary transmission is in the low gear position. . 2. The inhibiting means includes a solenoid valve that controls the supply of hydraulic medium to the high speed friction engagement device and the low speed friction engagement device of the auxiliary transmission, and solenoid valve control means that controls the solenoid valve. A control device according to claim 1, characterized in that: 3. When the inhibiting means is a switching valve that selectively guides the hydraulic medium to the highest speed friction engagement device and the low speed friction engagement device of the auxiliary transmission, and the operating position of the auxiliary transmission is in the low speed position. A patent claim characterized in that the vehicle has a control pressure circuit that guides control pressure to maintain the switching valve in a low gear position, and an opening/closing valve that opens and closes the control pressure oil passage in relation to governor pressure related to vehicle speed. The control device according to item 1.