JP2939976B2 - Speed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a speed control device using an electronically controlled automatic transmission mounted on a vehicle.

(Conventional technology) Conventionally, there is a constant speed traveling device as a device that automatically keeps a vehicle at a constant speed. In this technique, the opening of a throttle valve of the engine is controlled, the driving torque of the engine is controlled, and the speed of the vehicle is adjusted.

(Problems to be solved by the invention) However, in the conventional device, since the throttle valve is adjusted, it is difficult to control the throttle valve.
For example, if the throttle valve is fixed to fully closed or fully open during acceleration or deceleration to a predetermined speed while the constant speed traveling device mounted on the vehicle is working, control can no longer be performed. I will.

Further, since control in a state where the throttle valve is almost fully closed is difficult to control, when the vehicle speed is low, the conventional constant speed traveling device cannot control the vehicle speed.

Therefore, an object of the present invention is to make it possible to control the speed of a vehicle even when the throttle valve is fully closed or almost fully open.

[Configuration of the invention]

(Means for Solving the Problems) The technical means of the present invention taken to solve the above problems includes a plurality of clutches and brakes that operate the speed control device by applying hydraulic pressure. An automatic transmission for changing a gear position by engagement / disengagement of a brake, application of a hydraulic pressure to the clutch and the brake, and hydraulic control means for independently controlling the applied hydraulic pressure, and An electronic control type automatic transmission, comprising: electronic control means for driving the hydraulic control means to control engagement / disengagement of the clutch and brake to change the gear position of the automatic transmission. Vehicle speed detecting means for detecting a running speed; input means for inputting instructions for setting and canceling at least constant speed running in a predetermined target speed range; and When there is a setting instruction for high-speed traveling, the target speed range and the traveling speed at that time are compared so that the clutch and brake engaging forces of the automatic transmission are changed in a direction in which both coincide with each other. The present invention is configured to include speed control means for controlling the hydraulic pressure applied to the clutch and the brake by the hydraulic control means and the electronic control means.

(Operation) According to the above-described means, the engagement of the brake and the clutch of the automatic transmission is changed by the speed control means via the hydraulic control means and the electronic control means of the electronically controlled automatic transmission, thereby driving the engine. The transmission amount of the torque to the wheels is controlled, and the traveling speed of the vehicle is maintained in a predetermined target speed range.

(Example) Hereinafter, an example using the present invention will be described with reference to the drawings. In the present embodiment, the automatic transmission main body uses a conventionally used 4-speed (with overdrive).

The operation of the automatic transmission will be described with reference to FIG. The turbine shaft 600, which is the input shaft of the overdrive mechanism 607, is connected to the engine via a torque converter. This turbine shaft 600 is the carrier 6 of the planetary gear set.
Connected to 09. Planetary pinion 610 rotatably supported by carrier 609 is OD planetary gear 601
Through the input shaft 611 of the gear transmission mechanism 608. The planetary pinion 610 is in mesh with the sun gear 612. A one-way clutch 606 and an OD clutch C0 are provided between the sun gear 612 and the carrier 609. An OD brake B0 is provided between the sun gear 612 and the housing 613. The input shaft 611 and the intermediate shaft 614 of the gear transmission 608
Between them, a forward clutch C1 is provided. A direct clutch C2 is provided between the input shaft 611 and the sun gear shaft 615. Sun gear shaft 615 and housing 6
13 and a second brake B1 is provided. A planetary pinion 619 rotatably supported by a carrier 617 connected to the output shaft 605 is connected to the intermediate shaft 614 via a planetary gear 604 and a carrier 618. The planetary pinion 619 is in mesh with the sun gear shaft 615. Planetary pinion 621 meshes with planetary gear 603 and sun gear shaft 615 connected to carrier 617. A 1st and Rev brake B2 is provided between the housing 613 and the carrier 620 that rotatably supports the planetary pinion 621. A one-way clutch 616 is provided between the carrier 620 and the housing 613. Incidentally, reference numeral 602 denotes an outer ring of the one-way clutch 616.

In this automatic transmission, the relationship between the clutches CO, C1, C2 and the brakes B0, B1, B2 and the shift speeds is as shown in the table below.

The clutches CO, C1, C2 and the brakes B0, B1, B2 are
The engagement and release are controlled by the hydraulic circuit shown in the figure.

In FIG. 2, hydraulic oil pumped by a hydraulic pump 702 from an oil reservoir 701 is supplied to a line pressure oil passage 704, and the oil pressure in the line pressure oil passage 704 (hereinafter referred to as line pressure).
Is regulated by a pressure control valve 703 controlled by a line pressure control solenoid valve 48. Line pressure oil passage 704b
Is connected to the line pressure oil passage 704 via a pressure regulating valve 703, but is provided with a solenoid valve 41 for controlling the clutch C0, a solenoid valve 42 for controlling the clutch C2, a solenoid valve 43 for controlling the brake B0, and a solenoid valve for controlling the brake B1. 44,
The brake B2 is connected to manual valves 705, 706, 707, 708, and 709 via a solenoid valve 45 for controlling the B2. The output of the hydraulic pump 702 is directly connected to the manual valves 705, 706, 707, 708, 709. And
The outputs of the manual valves 705, 706, 707, 708 are connected to the clutch C0, the clutch C2, the brake B0, and the brake B1, respectively. The output of the manual valve 709 is connected to the brake B2 via the valve 710. The valve 710 is connected to the shift valve 711 via the low and reverse prohibition solenoid valve 46. Shift valve 711 is also connected to manual valve 706. The shift valve 711 moves in response to the operation of a shift lever (not shown), and the hydraulic pressure from the hydraulic pump 702 is applied to the inside thereof at times other than the P range. Also, 1st, 2nd, 3rd and OD
Sometimes, hydraulic pressure is applied to the clutch C1. Then, the hydraulic pressure is supplied to the manual valve 706 in the L and R ranges, and the hydraulic pressure is supplied to the low and reverse prohibition solenoid valves 46 in the L and R ranges.

With this configuration, the solenoid valve for clutch C0 control
When the valve 41 is opened, the valve of the manual valve 705 moves, the output of the hydraulic pump 702 is applied to the clutch C0, and the clutch C0 is engaged. When the clutch C0 control solenoid valve 41 is closed, no oil pressure is applied to the clutch C0, and the clutch C0 is released.

The clutch C1 is connected to the shift valve 711 at 1st, 2nd, 3rd and OD.
The clutch is engaged by applying hydraulic pressure, and is released without applying hydraulic pressure in other ranges.

In the clutch C2, if the solenoid valve 42 for controlling the clutch C2 is opened, the valve of the manual valve 706 moves,
Oil pressure is applied to the clutch C2, and the clutch C2 is engaged.
When the clutch C2 control solenoid valve 42 is closed, no oil pressure is applied to the clutch C2, and the clutch C2 is released. However, when the shift valve 711 is in the L, 2 range, the hydraulic pressure is supplied to the manual valve 706, and the hydraulic pressure to the clutch C2 is cut regardless of the movement of the solenoid valve 42 for controlling the clutch C2.

In the brake B0, if the brake B0 control solenoid valve 43 is opened, the valve of the manual valve 707 moves,
The hydraulic pressure is no longer applied to the brake B0, and the brake B0 is released. When the brake B0 control solenoid valve 43 is closed, hydraulic pressure is applied to the brake B0, and the brake B0 is engaged.

In the brake B1, if the brake B1 control solenoid valve 44 is opened, the valve of the manual valve 708 moves,
The hydraulic pressure is no longer applied to the brake B1, and the brake B1 is released. When the brake B1 control solenoid valve 44 is closed, hydraulic pressure is applied to the brake B1, and the brake B1 is engaged.

In the brake B2, if the solenoid valve 45 for brake B2 control is opened, the valve of the manual valve 709 moves,
The hydraulic pressure is no longer applied to the brake B2, and the brake B2 is released. When the brake B2 control solenoid valve 45 is closed, hydraulic pressure is applied to the brake B2 via the valve 710, and the brake B2 is engaged. However, when the low / reverse prohibition solenoid valve 46 is turned on in the R range and the L range, hydraulic pressure is applied to the valve 710 to cut off the supply of the hydraulic pressure to the brake B2 and release the brake B2.

In another configuration, reference numeral 712 denotes a lock-up control valve, and when the lock-up control solenoid valve 47 is turned on, the output shaft of the engine and the turbine rotating shaft 600 are directly connected to each other to be in a lock-up state.

Each solenoid valve is driven by an electronic control circuit to be described later, and each clutch / brake is set to a first position in accordance with running conditions.
It is controlled so as to have a table relationship. Each solenoid valve is operated at a relatively high frequency by an electronic control circuit described later.
The opening degree of each manual valve can be adjusted by repeating ON-OFF and controlling the duty ratio. When the duty ratio is increased, the manual valve is greatly opened, and the hydraulic pressure generated by the hydraulic pump 702 is quickly applied to each clutch / brake, so that the operating speed of each clutch / brake is increased. Also, when the duty ratio is reduced, the opening of the manual valve decreases, and it takes time for the hydraulic pressure generated by the hydraulic pump 702 to reach each clutch / brake, and the operating speed of each clutch / brake decreases. Therefore, by controlling the duty ratio, the operating speed of each clutch / brake can be adjusted, and the shock generated when each clutch / brake is engaged can be reduced, and the transmission efficiency can be improved.

FIG. 3 shows an electronic control circuit for driving each solenoid valve in the hydraulic circuit.

An input terminal of a constant voltage power supply circuit 22 is connected via a ignition switch 21 to a terminal of a battery 20 mounted on the vehicle. The output terminals of the constant voltage power supply circuit 22 are connected to power supply terminals VCC and GND of the central processing unit CPU.
The constant voltage power supply circuit 22 is for converting the output voltage of the battery 20 to a voltage at which the central processing unit CPU can operate.

Each input terminal of the central processing unit CPU has an engine rotation sensor 23, a turbine rotation sensor 24, and an output shaft rotation sensor 2
5, throttle sensor 26, neutral start switch 2
7, an overdrive cut switch 31, an idle switch 32, a brake switch 33, and a walking mode switch 34 are connected. In FIG. 3, the input interface of each sensor and switch is omitted for simplification.

The engine speed sensor 23 is used to determine the engine speed NE of the vehicle.
Is a sensor that detects The engine rotation sensor is provided near the output shaft of the engine, and outputs a pulse signal having a frequency corresponding to the rotation speed of the engine. In the present embodiment, the engine rotation sensor is a rotation sensor of an electromagnetic pickup type installed facing teeth of a ring gear (not shown) attached to the output shaft of the engine.
Outputs 120 pulses for rotation. This output is sent to the central processing unit CPU.

The turbine rotation sensor 24 detects the rotation speed NT of the turbine shaft 600.
Is a sensor that detects The turbine rotation sensor 24 is provided near the turbine shaft 600 and outputs a pulse signal having a frequency corresponding to the rotation speed of the turbine shaft 600. In the present embodiment, the turbine rotation sensor is an electromagnetic pickup-type rotation sensor that is installed to face the gear teeth (not shown) of the turbine shaft 600.
Output pulse. This output is sent to the central processing unit CPU.

The output shaft rotation sensor 25 is a sensor that detects the rotation speed N0 of the output shaft 605 of the automatic transmission. Output shaft rotation sensor 25
Is provided near the output shaft 605 of the automatic transmission and outputs a pulse signal having a frequency corresponding to the rotation speed of the output shaft 605 of the automatic transmission. In this embodiment, the output shaft rotation sensor 25
Numeral denotes an electromagnetic pickup type rotation sensor installed opposite to the teeth of a gear (not shown) attached to the output shaft 605, and outputs 18 pulses for one rotation of the gear. This output is sent to the central processing unit CPU. Note that the output shaft rotation sensor may be replaced by another type of vehicle speed sensor that detects the speed of the vehicle if the relationship between the output shaft 605 of the automatic transmission and the rotation speed of the wheels (not shown) is clearly understood. .

The throttle sensor 26 is a sensor that detects the opening of a throttle valve (not shown) of the engine. The throttle sensor 26 detects the rotation angle of the throttle valve with a switch and divides the opening of the throttle valve into digital and mechanical throttle sensors. The throttle sensor 26 converts the rotation angle of the throttle valve into a voltage value, and an A / D converter. There are analog and electric throttle sensors that divide the opening of a throttle valve by using a throttle valve. In the present invention, both throttle sensors are provided and used by switching, but in an ordinary device, only one of them may be used.
The throttle sensor 26 outputs a signal obtained by dividing the opening of the throttle valve by 16 from four signal lines. The fully closed state is θ0, and the fully open state is θ15. θ0 between θ0 and θ15
θ14.

The neutral start switch 27 detects the position of a shift lever (not shown), and includes a D (drive) range switch, an L (low) range switch, and 2 (second).
It has a range switch, 3 (third) range switch, N (neutral) range switch, R (reverse) range switch and P (parking) range switch, and D, L, 2,
Detect each range of 3, N, R, P.

The overdrive cut switch 31 is a switch operated by the driver and prohibits overdrive.
This is a switch for setting permission. Instead of the overdrive cut switch 31, for example, an interface for inputting an overdrive cut signal from the constant speed traveling device for preventing the constant speed traveling device from increasing the speed during constant speed traveling may be provided.

The idle switch 32 is a sensor for detecting an idle state of the engine, and its contact is turned on at the time of idling (in this embodiment, the throttle opening is 1.5% or less).

The brake switch 33 detects whether the brake is on or off.

The walking mode switch 34 is a switch operated by the driver, and is a switch for selecting a walking mode. In the walking mode, the gear position or the oil pressure is adjusted by the processing of the central processing unit CPU, which will be described later, so that the speed of the vehicle is about the speed at which a person walks.

Each output terminal of the central processing unit CPU has a walking speed lamp 40, a solenoid valve 41 for controlling the clutch C0, a solenoid valve 42 for controlling the clutch C2, and a brake B0.
The control solenoid valve 43, the brake B1 control solenoid valve 44, the brake B2 control solenoid valve 45, the low / reverse shift prohibition solenoid valve 46, the lockup control solenoid valve 47, and the line pressure control solenoid valve 48 are connected. ing. In FIG. 3, the output interface or driving device of each lamp and solenoid is omitted for simplicity.

The walking speed ramp 40 is a central processing unit.
This lamp is controlled by the CPU and lights up when walking speed is controlled.

Solenoid valve 41 for clutch C0 control, solenoid valve 42 for clutch C2 control, solenoid valve 43 for brake B0 control, solenoid valve 44 for brake B1 control, solenoid valve 45 for brake B2 control, solenoid valve 46 for low / reverse shift inhibition, Solenoid valve 47 for lock-up control and solenoid valve 48 for line pressure control
Are respectively controlled by the central processing unit CPU.

The central processing unit CPU has internal memories such as RAM and ROM, a timer, and a register. When the ignition switch is turned on and voltage is supplied to the central processing unit CPU, the main routine shown in FIG. 4 is executed. Begin to.

The fourth is a flowchart of the main routine of the central processing unit CPU, the vehicle speed sensor interrupt, the turbine rotation sensor interrupt, the engine rotation sensor interrupt, and the periodic interrupt.

(Main Routine) When the central processing unit CPU starts, first, the setting of the input / output direction of each input / output port, the initialization of each memory, and the setting of the presence / absence of an interrupt are performed (step 5).
0).

After that, an input / output read routine is executed to read the status of each sensor and each switch connected to the input, remove noise, and set data according to the status of each sensor and each switch (step 51). .

Next, a rotation speed calculation processing routine is executed to calculate the vehicle speed, the turbine rotation speed NT, and the engine rotation speed NE (step 52).

The calculation of the engine speed NE is performed by the following equation. still,
Since the output from the engine rotation sensor 23 has a high frequency, it is calculated after dividing the frequency by eight.

Here, nEi: engine speed by the current pulse, TEi: time count up to the edge of the first pulse exceeding 10 ms from the previous pulse, PCi: number of pulses in TEi, 8 × 10 ^-6 : detection time The minimum unit (8 μS).

The calculation of the turbine rotational speed NT is performed by the following equation. still,
Since the output from the turbine rotation sensor 24 has a high frequency, it is calculated after dividing by four.

Here, nTi: the number of turbine rotations by the current pulse, TTi: the time count up to the edge of the first one pulse exceeding 10 ms from the previous pulse, and PCTi: the number of pulses in TTi.

 The calculation of the output shaft rotation speed N0 is performed by the following equation.

Here, n0i: the number of revolutions of the output shaft by the current pulse, T0i: the time count up to the edge of the first one pulse exceeding 10 ms from the previous pulse, and PC0i: the number of pulses in T0i.

The first calculation of the output shaft rotational speed N0 after the vehicle stops (determined in the regular interrupt routine described later) And

Since the gear ratio and the radius of the wheels between the output shaft 605 and the axle (not shown) are obtained in advance, the vehicle speed can be obtained from the output shaft rotation speed N0.

 The vehicle acceleration AG is obtained by the following equation.

When N0i ≧ N0 (i-0) The first calculation after the vehicle stops is And When N0i <N0 (i-1), AG is set to the maximum value (￥
FF).

Next, a control vehicle speed difference / slip ratio calculation routine is executed, and a control vehicle speed difference / slip ratio is obtained (step 53). The turbine slip ratio SLPt is obtained by the following equation.

Next, a line pressure control / shift control routine is executed,
The setting and control of the line pressure, the setting of the control mode, and the shift determination are performed (step 54). The line pressure set value is set by the throttle opening and the turbine speed NT. The line pressure control solenoid valve 48 is duty-driven according to this set value.

In the shift control, as is well known, the presence or absence of a shift determination is determined based on a throttle opening, a vehicle speed, and a shift diagram created in advance at the current shift stage.

When the above processing is completed, it is next determined that the gear can be shifted in the line pressure control / shift control routine (step 55), and it is determined that the gear is not currently being shifted (step 55).
56) At the time, a shift processing routine is executed, and a shift processing is performed (step 57). If it is determined in step 55 that the shift is not possible, or if it is determined in step 56 that the gear is being shifted, the shift process in step 57 is not executed, and the process proceeds to step 58.

Next, in step 58, a lock-up determination routine is executed. If it is determined that there is a change in lock-up (step 59), a lock-up processing routine is executed, and lock-up processing is performed (step 60). ). Here, the engine brake control is performed as a part of the lockup processing. Here, when the throttle opening is fully closed (idle contact is on) and the vehicle speed is equal to or higher than the set vehicle speed (15 km / h), the lock-up control solenoid valve 47 is operated while the engine speed NE <turbine speed NT regardless of the shift speed. The engine brake is turned on by directly connecting the output shaft of the engine and the turbine rotating shaft 600. After the elapse of 0.6 seconds in a state where the idle contact is OFF or the engine speed NE> the turbine speed NT, a shift determination based on the gear stage at that time is performed. If it is determined in step 59 that there is no lockup change, the process proceeds to step 63 without executing the lockup processing.

Next, a walking speed control routine is executed to perform walking speed control (step 6).
3). Walking speed control is a constant speed traveling mode in which the vehicle travels at a constant speed of about 3 km / h. It can be used privately when the vehicle and workers outside the vehicle are working while moving, or when traveling at a constant speed during traffic congestion. It is activated by the driver turning off the brake switch 33 and turning on the walking mode switch 34. In the walking speed control, as will be described later, the line pressure control and the shift between 1st and 2nd are performed in combination. If the above conditions disappear and the driver opens the throttle opening by 1/4 or more, the control is stopped.

Next, fail-safe control is performed, and fail-safe processing is performed. (Step 64).

Finally, an output control routine is executed, and output control is performed (step 65).

(Interrupt routine) The outputs of the output shaft rotation sensor 25, the turbine rotation sensor 24, and the engine rotation sensor 23 are respectively connected to the interrupt input terminals of the central processing unit CPU. A shaft rotation sensor interruption routine, a turbine rotation sensor interruption routine, and an engine rotation sensor interruption routine are executed.

In the output shaft rotation sensor interruption routine, first, the time at the time of interruption is read from a timer, and here, a calculation flag for calculating the output shaft rotation speed is turned on. (Step 6
6). Next, a failure of the turbine rotation sensor 24 and the engine rotation sensor 23 is determined. (Steps 67, 68). This failure determination is made by comparing the output shaft speed N0 with the turbine speed NT and the engine speed NE.

In the turbine rotation sensor interruption routine, first, the time at the time of interruption is read from a timer, and when the interruption is counted four times in order to divide the input pulse by four, the operation flag for turbine speed calculation is turned on ( Step 69). Then, a failure of the engine rotation sensor 23 and the output shaft rotation sensor 25 is determined (Steps 70 and 7).
1). This failure determination is made by comparing the turbine speed NT with the engine speed NE and the output shaft speed N0.

The frequency division may be performed by installing a frequency dividing circuit between the central control unit CPU and the rotation sensor.

In the engine rotation sensor interruption routine, first, the time at the time of interruption is read from a timer. Here, when the interruption is counted eight times in order to divide the input pulse by eight, the operation flag for calculating the engine speed is turned on ( Step 72). Then, a failure of the output shaft rotation sensor 25 and the turbine rotation sensor 24 is determined. (Step 73,
74). This failure determination is made by comparing the engine speed NE with the output shaft speed N0 and the turbine speed NT.

The frequency division may be performed by installing a frequency dividing circuit between the central control unit CPU and the rotation sensor.

The central control unit CPU has a periodic interrupt that is generated every time a predetermined time elapses. In this embodiment, 4 ms
A periodic interrupt routine is executed each time. here,
First, various timers used for control are subtracted. (Step 75). Next, it is determined that the vehicle is stopped (step 76). In this embodiment, the vehicle stop speed N stop
= Stop the vehicle below 144rpm (about 3km). The vehicle is stopped when there is no pulse with an input frequency T stop = 23.13 ms or more to the central control unit CPU.

Hereinafter, details of each control will be described with reference to flowcharts.

FIG. 5 is a flowchart of a line pressure control routine.

(Line Pressure Control) First, the throttle opening data obtained in the input signal reading routine is read, the turbine rotation range is searched from the turbine rotation speed NT, and the line pressure is obtained from the turbine rotation range and the throttle opening data THR (step 148). ~ 15
0). The line pressure is obtained from a line pressure map shown in FIG. The line pressure map shown in FIG. 7 is obtained from measured values.
FIG. 8 shows the line pressure at which the efficiency at the time of shifting is better than the measured value. This is converted into the line pressure map shown in FIG. A duty value for driving the line pressure control solenoid valve 48 is calculated from the line pressure thus obtained (step 151). Then, as described later, when the walking flag that is turned on during the walking speed control is off, the calculated duty value is output to drive the line pressure control solenoid valve 48 (steps 152 and 15).
3). Thus, the line pressure is controlled to the determined value.
Next, a line pressure radix is obtained from the obtained line pressure (step 154). The line pressure radix divides the line pressure between the minimum value and the maximum value into eight equal parts, so that other control using the line pressure is easy to use.

(Walking Speed Control Routine) FIG. 6 is a flowchart of a walking speed control routine.

If the throttle opening is large and the brake switch 33 is ON (intention to stop) or the walking mode switch 34 is OFF (steps 256a to 256c), the walking flag, the walking timer, and the walking shift timer are cleared (steps 257 and 258).

When the determination results in steps 256a and 256b are both No and the walking mode switch 34 is on, if the walking flag is not on and the vehicle speed is 3 km / h or less, the walking flag is turned on, and 2nd is set in the output buffer. Set and output engagement for 2nd with a duty of 60% (steps 256a-256c, 259-263). Then, the walking timer and the walking shift timer are started (steps 264 and 265).

If the determination results in steps 256a and 256b are both No, the walking mode switch 34 is on, the walking flag is on, and the vehicle speed is less than 4 km / h, the following operation is performed. If the value of the output buffer is not 2nd or the value of the output buffer is 2nd and the walking shift timer has not expired and the walking timer has expired, start the walking timer and set the line pressure to 8 kg / cm ² or more. If not, the line pressure data is increased by ² kg / cm ² and then the line pressure control solenoid valve 48 is controlled (steps 256a to 256c, 25
9, 266-272). When the value of the output buffer is 2nd and the walking shift timer has expired, the walking shift timer is cleared and 1s is stored in the output buffer.
t is set, and 1st is output with a 60% duty (steps 273 to 277). Then, the walking timer is started (step 277).

If the determination results in steps 256a and 256b are both No, the walking mode switch 34 is on, the walking flag is on, and the vehicle speed is 4 km / h or more, the following operation is performed. First, clear the walking shift timer. Next, when the vehicle speed is 6-7 km / h and the walking timer ends, the line pressure is set to 0.5 kg / cm ^2.
It lowers and starts the walking timer (steps 279,284 to 287). When the vehicle speed is 7 km / h or more, and when the walking timer ends and the line pressure is not at the lower limit, the line pressure is reduced by 1 kg / cm ² and the walking timer is started (steps 279 to 283).

When the walking mode switch 34 is ON and the above control is being performed, the walking speed lamp 40 is turned on.

As described above, the line pressure of the hydraulic circuit is changed according to the vehicle speed, and the line pressure is reduced at a relatively high vehicle speed during the walking mode, and is increased at a relatively low vehicle speed during the walking mode. As a result, at a high vehicle speed, the engagement of the clutch or the brake during engagement of the automatic transmission is weakened, and the state becomes close to neutral. Therefore, the speed of the vehicle decreases on a normal flat road. At low vehicle speeds, the clutch or brake during engagement of the automatic transmission is reliably engaged, so that the driving torque of the engine is reliably transmitted to the wheels, and the vehicle speed increases. Therefore, the speed of the vehicle is kept almost constant.

〔The invention's effect〕

As described above, the technical idea of maintaining the speed of the vehicle in a predetermined target speed range by controlling the amount of transmission of the driving torque of the engine to the wheels by changing the engagement force of the brake and the clutch of the automatic transmission. According to the present invention, the following excellent effects can be obtained.

(A) In contrast to the conventional speed control device that controls the driving torque of the engine by controlling the opening degree of the throttle valve of the engine to keep the running speed of the vehicle constant, the opening degree of the throttle valve in the present invention is Irrespective of this, the running speed of the vehicle can be maintained in a predetermined target speed range. for that reason,
For example, the traveling speed of the vehicle can be maintained in the target speed range even when the throttle valve is fully closed, such as during traffic congestion, which could no longer be controlled by the conventional speed control device. The control range can be expanded.

(B) Further, since the opening of the throttle valve is not controlled as in the conventional device, the throttle valve is fixed to the fully open state due to the failure of the control device, and the traveling speed of the vehicle increases against the driver's intention. The safety can be improved without causing any trouble.

(C) Since the existing hydraulic control device and electronic control device of the electronically controlled automatic transmission can be used, the manufacturing cost of the vehicle speed control device can be reduced.

[Brief description of the drawings]

FIG. 1 shows an automatic transmission of an electronically controlled automatic transmission according to one embodiment of the present invention. FIG. 2 shows a hydraulic circuit for driving the automatic transmission of FIG. FIG. 3 shows an electronic control circuit for controlling the hydraulic circuit of FIG. FIG. 4 is a flowchart of a CPU main routine, a vehicle speed sensor interrupt, a turbine rotation sensor interrupt, an engine rotation sensor interrupt, and a periodic interrupt of the electronic control circuit of FIG. FIG. 5 is a flowchart of the line pressure control of the CPU of the electronic control circuit of FIG. FIG. 6 is a flowchart of a walking speed control routine of the CPU of the electronic control circuit of FIG. FIG. 7 shows a line pressure map for setting the line pressure used in the embodiment of the present invention. . FIG. 8 is a characteristic diagram showing the relationship between the turbine speed, the throttle opening, and the line pressure in the embodiment of the present invention. CPU ... Central processing unit, 20 ... Battery, 21 ... Ignition switch, 22 ... Constant voltage power supply circuit, 23 ...
Engine rotation sensor, 24 ... Turbine rotation sensor, 25 ...
… Output shaft rotation sensor, 26 …… Throttle sensor, 27 ……
Neutral start switch, 31 ... Overdrive cut switch, 32 ... Idle switch, 33 ... Brake switch, 34 ... Walking mode switch,
40: Walking speed ramp, 41: Clutch C0
Solenoid valve for control, 42 ... Solenoid valve for controlling clutch C2, 43 ... Solenoid valve for controlling brake B0, 44 ... Solenoid valve for controlling brake B1, 45 ...
Solenoid valve for brake B2 control, 46 ... Solenoid valve for low and reverse prohibition, 47 ... Solenoid valve for lock-up control, 48 ... Solenoid valve for line pressure control, B2 ... 1st and Rev brake, C2 ... Direct Clutch, B1 …… Second brake, C0 …… OD clutch, B0 …… OD brake, C1 …… Forward clutch, 60
0… Turbine shaft, 601… OD planetary gear, 605…
Output shaft, 606,616 1-way clutch, 607 Overdrive mechanism, 608 Gear transmission mechanism, 609,617,618
… Carrier, 610,619,621 …… Planetary pinion, 611
…… Input shaft, 612 …… Sun gear, 613 …… Housing, 61
4 ... Middle shaft, 615 ... Sun gear shaft, 701 ... Oil reservoir, 702
…… Hydraulic pump, 703 …… Pressure regulating valve, 704 …… Line pressure oil passage, 705,706,707,708,709 …… Manual valve, 710
…… Valve, 711 …… Shift valve, 712 …… Lock-up control valve.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B60K 31/00

Claims (1)

(57) [Claims] 1. An automatic transmission having a plurality of clutches and brakes that operate by applying hydraulic pressure, and changing a gear position by engaging and disengaging the clutch and brake, and applying hydraulic pressure to the clutch and brake. And hydraulic pressure control means for independently controlling the applied hydraulic pressure, and driving the hydraulic pressure control means in accordance with the running state of the vehicle to control the engagement and disengagement of the clutch and the brake to thereby control the automatic transmission. Electronic control means for changing the gear position of the machine,
Electronically controlled automatic transmission; vehicle speed detecting means for detecting a running speed of the vehicle; input means for inputting instructions for setting and canceling at least constant speed running in a predetermined target speed range; When the setting instruction for the constant speed traveling is issued from the means, the engaging force of the clutch and the brake of the automatic transmission is changed in a direction in which the target speed range and the traveling speed at that time are compared and the two coincide with each other. Speed control means for controlling the hydraulic pressure applied to the clutch and the brake by the hydraulic pressure control means and the electronic control means.