JPH02109741A - Speed control device - Google Patents

Abstract

PURPOSE:To prevent a vehicle speed from rising at the time of starting control by making liquid pressure generated by a liquid pressure switching means to be controlled according to vehicle speed with a pressure control means, in response to indication of a indicating means, in the vehicle having a liquid pressure switching means for controlling the switching means for the speed change stage of an automatic transmission. CONSTITUTION:The second value is set to an output buffer when a walking mode switch 34 is ON and when a vehicle speed is below about 3km/h in a CPU, in the case of walking speed control. Also, when the walking mode switch 34 is ON and vehicle speed is less than about 4km/h, in the time of the value of the output butter not in second, a walking timer is started and after raising line pressure data by about 2kg/h if line pressure is not about 8km/h or more, a line pressure controlling solenoid valve 48 is controlled. Mean-while, when the vehicle speed is in 6 - 7km/h and the walking timer comes to an end, the line pressure is reduced by 0.5km/cm<2> and at the same time the line pressure is reduced by 1kg/cm<2> when the vehicle speed is over about 7km/h and the walking timer is ended.

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.

(Prior Art) Conventionally, there is a constant speed traveling device as a device that automatically maintains a vehicle at a constant speed. This controlled the opening of the engine's throttle valve, controlled the engine's driving torque, and adjusted the speed of the vehicle.

(Problem 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 in range 1. For example, when the constant speed traveling device is working, If the throttle valve is stuck fully closed or fully open during acceleration or deceleration, control will no longer be possible.

Furthermore, since it is difficult to control the throttle valve when it is close to fully open, the conventional constant speed driving system cannot control the vehicle speed when the vehicle speed is low.

Therefore, in order to control the speed of the vehicle even when the throttle valve is fully closed or close to fully open, the fluid pressure of the fluid pressure switching means that controls the clutch and brake of the automatic transmission is adjusted to control the speed. is possible.

By using this means, it is possible to drive at a constant speed at a low speed of 10 km or less.

However, in this method, if the control is started with the gear position at the beginning of the control, the vehicle will be accelerated until the fluid pressure stabilizes, and it may not be possible to control the vehicle properly.

Therefore, an object of the present invention is to prevent an increase in vehicle speed at the start of control in a speed control device that controls fluid pressure and performs constant speed travel.

[Structure of the invention]

(Means for Solving the Problem) The technical means used in the present invention to solve the above problem includes a clutch and a brake that are operated by applying fluid pressure, and a method for engaging and disengaging the clutch and brake. an automatic transmission that changes the gear ratio depending on the timing, a fluid pressure switching device that independently controls the application of fluid pressure to the clutch and the brake, and a fluid pressure switching device that drives the fluid pressure switching device depending on the running state of the vehicle; an electronically controlled automatic transmission device comprising an electronic control means for changing engagement/disengagement of the clutch and the brake; a vehicle speed detection means for detecting the speed of the vehicle;
A speed control device comprising a pressure control means for controlling fluid pressure to the clutch and brake according to the speed, further comprising an instruction means for instructing the pressure control means to start pressure control, the electronic control means The fluid pressure switching means is driven to change the gear position to a high speed side in response to an instruction from the indicating means, and then the fluid pressure switching means is driven to change the gear position to a low speed side. This is what happened.

(Function) According to the above technical means, in a vehicle having a fluid pressure switching means for controlling a clutch or a brake that switches gears of an automatic transmission, the fluid pressure switching means is generated by the pressure control means according to the speed of the vehicle. The fluid pressure is controlled.

When the fluid pressure is high, the clutches and brakes are fully engaged and the engine's driving force is reliably transmitted to the wheels.On the contrary,
If the fluid pressure is low, the clutch and brake will not work as well, resulting in a state close to neutral. At this time, the rate at which the engine's driving force is transmitted to the wheels decreases, and the vehicle decelerates. Therefore, by controlling the fluid pressure according to the vehicle speed, the speed of the vehicle can be controlled.

At the start of this control, the gear position of the automatic transmission is changed to a higher vehicle speed side, and the driving torque is reduced. Therefore, an increase in vehicle speed is suppressed.

(Example) Hereinafter, an example using the present invention will be described based on the drawings. In this embodiment, the automatic transmission body uses a conventional 4-speed automatic transmission (with overdrive).

The operation of this automatic transmission will be explained with reference to FIG.

Turbine shaft 600, which is the input shaft of overdrive machine +#607, is coupled to the engine via a torque converter. This turbine shaft 600 is connected to a carrier 609 of a planetary gear system. A planetary pinion 610 rotatably supported by a carrier 609 is connected to an input shaft 611 of a gear transmission mechanism 608 via an OD planetary gear 601. Also planetary pinion 6
10 meshes with sun gear 612. sun gear 61
2 and the carrier 609 is a one-way clutch 606.
and an OD clutch CO are provided. sun gear 612
An OD brake BO is provided between the housing 613 and the housing 613. A forward clutch C1 is provided between the input shaft 611 and the intermediate shaft 614 of the gear transmission mechanism 608.

Further, a direct clutch C2 is provided between the human power shaft 611 and the sun gear shaft 615. sun gear shaft 615
A second brake B1 is provided between the housing 613 and the housing 613. Carrier 6 connected to output shaft 605
A planetary pinion 6 rotatably supported by 17
19 is an intermediate shaft 614 via a gear and a carrier 618
is connected to. Further, the planetary pinion 619 meshes with the sun gear shaft 615. Planetary pinion 621 meshes with carrier 617 and sun gear shaft 615. Planetary pinion 621 and housing 6
13, a tst and Rev brake B2 is provided. Further, a one-way clutch 616 is provided between the planetary pinion 621 and the housing 613.

In this automatic transmission, clutches Co and CL.

The relationship between C2, brakes BO, Bl, and B2 and the gears is as shown in the table below.

○: Engaged ×: Non-engaged Clutches Co, C1, C2 and brakes BO, B
1 and B2 are controlled in their engagement and release by the hydraulic circuit shown in FIG.

Referring to FIG. 2, a hydraulic pump 70 is connected to an oil reservoir 701.
The pressure regulating valve 703, which is controlled by the line pressure control solenoid valve 48, regulates the hydraulic pressure of the line pressure oil passage 704. Line pressure oil path 7
04b is connected to a line pressure oil passage 704 through a pressure regulating valve 703, and includes a solenoid valve 41 for controlling the clutch CO, a solenoid valve 42 for controlling the clutch 02, and a solenoid valve 43 for controlling the brake 82. Brake B
1 control solenoid valve 44. The brake 82 is connected to manual valves 705, 706, 707, 708, and 709 via solenoid valves 45, respectively. Also, manual valves 705, 706, 707
, 708, 709 are directly connected to the output of the hydraulic pump 702. And manual valve 705, 70
Clutch CO, clutch C2, brake BO, and brake B1 are connected to the outputs of 6707 and 708, respectively. The output of manual valve 709 is connected to brake B2 via valve 710. Valve 710 is connected to shift valve 711 via low/reverse prohibition solenoid valve 46. Shift valve 711 is also connected to manual valve 706. This shift valve 711 moves in response to the operation of the shift lever,
Hydraulic pressure from a hydraulic pump 702 is applied to the inside when the position is not in the P range. Also 1st, 2nd
, 3rd and OD, hydraulic pressure is applied to the clutch CI. Then, hydraulic pressure is supplied to the manual valve 706 when in the L and 2 ranges, and low when in the L and R ranges.

Hydraulic pressure is supplied to the reverse prohibition solenoid valve 46.

With this configuration, when the clutch CO control solenoid valve 41 is opened, the manual valve 705 moves, the output of the hydraulic pump 702 is applied to the clutch CO, and the clutch CO is engaged. If the clutch 02 control solenoid pulp 41 is closed, no oil pressure is applied to the clutch CO.
Clutch CO is released.

Clutch C1 includes 1st, 2nd, 3rd and OD.
At times, hydraulic pressure is applied and engaged, and when in other ranges, no hydraulic pressure is applied and it is released.

In the clutch C2, when the clutch 02 control solenoid valve 42 is opened, the manual valve 706 is moved, hydraulic pressure is applied to the clutch C2, and the clutch CO is engaged. If the clutch 02 control solenoid valve 42 is closed, no hydraulic pressure is applied to the clutch C2, and the clutch C
2 is released. However, due to the shift valve 711, 2
When in the range mode, hydraulic pressure is supplied to the manual valve 706, and the hydraulic pressure to the clutch C2 is cut off regardless of the movement of the clutch 02 control solenoid valve 42.

In the brake BO, when the brake BOm control solenoid valve 43 is opened, the manual valve 707 is moved, hydraulic pressure is no longer applied to the brake BO, and the brake BO is released. When the brake 82 control solenoid valve 43 is closed, hydraulic pressure is applied to the brake BO,
Brake BO is engaged.

In the brake B1, when the brake Bl control solenoid valve 44 is opened, the manual valve 708 is moved, hydraulic pressure is no longer applied to the brake B1, and the brake B1 is released. When the brake Bl control solenoid valve 44 is closed, hydraulic pressure is applied to the brake B1, and the brake B1 is engaged.

In the brake B2, when the solenoid valve 45 for controlling the brake 82 is opened, the manual valve 709 moves, oil pressure is no longer applied to the brake B2, and the brake B2 is released. When the brake 82 control solenoid pulp 45 is closed, the brake B2 is activated via the valve 710.
Hydraulic pressure is applied to the brake B2, and the brake B2 is engaged. However, when the low and reverse prohibition solenoid valves 46 are turned on in the R and L ranges, hydraulic pressure is applied to the valve 710, cutting off the supply of hydraulic pressure to the brake B2.
Release brake B2.

In other configurations, 712 is a lock-up control valve, and when the lock amplifier control solenoid valve 47 is turned on, the output shaft of the engine and the turbine rotating shaft 600 are directly connected, resulting in a lock-up state.

Each solenoid valve is driven by an electronic control circuit, which will be described later, and the clutches and brakes are controlled so that the relationships shown in Table 1 are achieved according to the driving conditions.

Further, each solenoid valve is repeatedly turned on and off at a relatively high frequency by an electronic control circuit to be described later, and by controlling the duty ratio, the opening degree of each manual valve can be adjusted. When the duty ratio is increased, the manual valve opens wide and the hydraulic pump 702
The hydraulic pressure generated by this is quickly applied to each clutch and brake, increasing the operating speed of each clutch and brake.

In addition, when the duty ratio is lowered, the opening degree of the manual valve becomes smaller, and it takes time for the hydraulic pressure generated by the hydraulic pump 702 to reach each clutch and brake, which slows down the operating speed of each clutch and brake. By controlling the duty ratio, the operating speed of each clutch/brake can be adjusted, reducing the shock that occurs when each clutch/brake is engaged, and improving transmission efficiency.

FIG. 3 shows an electronic control circuit that drives each solenoid valve in the hydraulic circuit.

An input end of a constant voltage power source 22 is connected to a terminal of a battery 20 mounted on the vehicle via an ignition switch 21. Power terminals VCC and GND of the central processing unit 1-CPU are connected to the output end of the constant voltage power supply 22. The constant voltage power supply 22 is for converting the output voltage of the battery 20 into a voltage at which the central processing unit CPU can operate.

Each input terminal of the central processing unit CPU is connected to an engine rotation sensor 23. Turbine rotation sensor 24° output shaft rotation sensor 25. Throttle sensor 26° Neutral start switch 27. 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 interfaces of each sensor and switch are omitted for simplicity.

The engine rotation sensor 23 is a sensor that detects the rotation speed of the vehicle engine. The engine rotation sensor is disposed near the output shaft of the engine and outputs a pulse signal having a frequency corresponding to the engine rotation speed. In this example,
The engine rotation sensor is an electromagnetic pickup type rotation sensor installed opposite the teeth of the ring gear attached to the output shaft of the engine.
Outputs 0 pulse. This output is from the central processing unit C.
Sent to PU.

The turbine rotation sensor 24 is a sensor that detects the rotation speed of the turbine. The turbine rotation sensor is disposed near the turbine rotation shaft and outputs a pulse signal having a frequency corresponding to the rotation speed of the turbine. In this embodiment, the turbine rotation sensor is an electromagnetic pickup type rotation sensor installed opposite the teeth of a gear attached to the turbine shaft 600, and outputs 57 pulses for one rotation of the gear. This output is sent to the central processing unit (CPU).

The output shaft rotation sensor 25 is a sensor that detects the rotation speed of the output shaft of the automatic transmission. The output shaft rotation sensor is disposed near the output shaft of the automatic transmission, and outputs a pulse signal having a frequency corresponding to the rotation speed of the output shaft of the automatic transmission. In this embodiment, the output shaft rotation sensor is an electromagnetic pickup type rotation sensor installed opposite the teeth of a gear attached to the output shaft, and outputs a pulse per day 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 with another type of vehicle speed sensor that detects the speed of the vehicle, as long as the relationship between the output shaft of the automatic transmission and the rotational speed of the wheels is clearly known.

The throttle sensor 26 is a sensor that detects the opening degree of the throttle valve of the engine. The throttle sensor includes a digital 2-mechanical throttle sensor that detects the rotation angle of the throttle valve with a switch and divides the opening of the throttle valve, and a digital two-mechanical throttle sensor that converts the rotation angle of the throttle valve into a voltage value and uses an A/D converter. There are analog and electric throttle sensors that are used to divide the throttle valve opening. In the present invention, both throttle sensors are provided and used selectively, but in a normal device, only one of them is sufficient. The throttle sensor outputs a signal obtained by dividing the opening degree of the throttle valve into 16 parts from four signal lines. Fully closed state is θO2
The fully open state is assumed to be θ15. Between θO and θ15 is θ1~θ
14.

The neutral start switch 27 detects the position of the shift lever, and is a D (drive) range switch and an L (low) range switch.

2 (second) range switch, 3 (third) range switch, N (neutral) range switch, R (reverse) range switch and P (parking) range switch, D, L, 2°3, N, R, P Detect each range.

The overdrive cut switch 31 is a switch operated by the driver, and is used to prohibit/disable overdrive.
This is a switch to set permissions.

Instead of this overdrive cut switch, for example, an interface may be provided that manually inputs an overdrive cut signal from the constant speed traveling device to prevent speed increase during constant speed traveling by the constant speed traveling device.

The idle switch 32 is a sensor that detects the idle state of the engine, and its contact is turned on when the engine is idle (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 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 approximately the same as a human's walking speed.

Each output terminal of the central processing unit cPU has a walking speed lamp 40. Solenoid pulp for clutch CO control 41. Solenoid valve 42 for clutch 02 control
．． Brake BO control solenoid valve 43. Brake 81 control solenoid valve 44. Brake B2 control solenoid valve 45. Solenoid pulp for inhibiting low/reverse shift 46. A solenoid valve 47 for lock-up control and a solenoid valve 48 for line pressure control are connected. In FIG. 3, output interfaces or drives for each lamp and solenoid are omitted for simplicity.

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

Clutch 02 control solenoid valve 41. clutch 0
2 control solenoid valve 42. Brake 31 control solenoid valve 43. Brake 31 control solenoid valve 44. Brake 82 control solenoid valve 45.
Solenoid pulp for inhibiting low/reverse shift 46. The lock-up control solenoid valve 47 and the line pressure control solenoid valve 48 are each controlled by the central processing unit 1-CPU.

The central processing unit (CPU) has internal memory such as RAM and RoM, timers, and registers, and when the ignition switch is turned on, the central processing unit (CPU)
When voltage begins to be supplied to , the main routine shown in FIG. 4 begins to be executed.

FIG. 4 is a flowchart of the main routine of the central control unit CPU, vehicle speed sensor interrupt, turbine rotation sensor interrupt, engine rotation sensor interrupt, and scheduled interrupt.

(Main Routine) When the central control unit CPU starts, it first sets the input/output direction of each input/output board, initializes each memory, and sets the presence/absence of interrupts (step 50).
).

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

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

The engine rotation speed NB is calculated using the following formula.

Note that since the output from the engine rotation sensor has a high frequency, it is calculated after dividing the frequency by eight.

n E(i-1) + n [! i NE = PCEi B frequency division 60nEi =
x xTBi
8xlO-6120 where, nl'i: Engine rotation speed due to the current pulse, TBi
: Time count to the edge of the first pulse exceeding l0RIs from the previous pulse, number of pulses in PCEis TBi, 5xio-':
This is the minimum unit of detection time (8 μs).

Calculation of the turbine rotation speed NT is performed using the following formula.

Note that since the output from the turbine rotation sensor has a high frequency, the frequency is divided by four before calculation.

n T (i-1) + n Ti NT = PCTi frequency divided by 4 60nTi =
X × TTi 5xxo-” 57 Here, nTi: Turbine rotation speed due to the current pulse, TTi
: Time count to the edge of the first pulse exceeding 10 m5 from the previous pulse, PCTis Number of pulses in TTi.

The output shaft rotation speed NO is calculated using the following formula.

no(i-1)+ n0i NO= PCOi 1 60n
et≧××T
Oi 5xto-18 Here, nQi: Output shaft rotation speed due to the current pulse, TOi:
PCO2 is the time count until the edge of the first pulse exceeding 10 m5 from the previous pulse, and PCO2 is the number of pulses during TOi.

The first output shaft rotational speed No. after the vehicle stops (determined in a scheduled interrupt routine to be described later) is calculated as follows: 144+n0i No=.

Since the gear ratio of the output shaft and the axle and the radius of the wheels are determined in advance, the vehicle speed can be determined from the output shaft rotational speed NO.

Vehicle acceleration AG is determined by the following formula.

When NO4≧N0(i4), N0i-No(i-1) IAC=
xTOi
5xxo-6 The first calculation after the vehicle stops is: N0i-1441 AG= xTOi
8X10-". Also, when NOi < No(i-1), A
Let G be the maximum value (¥FF).

Next, a control vehicle speed difference and slip ratio calculation routine is executed, and a control vehicle speed difference and slip ratio are determined (step 53). The turbine slip ratio 5LPt is determined by the following equation.

T SLPt = xloo (%) E Next, a line pressure control/shift control routine is executed, and line pressure setting and control, control mode setting, and shift determination are performed (step 54).

The line pressure set value is set by the throttle opening and turbine rotation speed. The line pressure solenoid is duty-driven according to this setting.

In the shift control, whether or not a shift is to be determined is determined based on a shift diagram created in advance using the throttle opening, vehicle speed, and current shift position.

When the above processing is completed, next, in the line pressure control/shift control routine, it is determined that shifting is possible, and if shifting is not currently in progress, a shifting processing routine is executed, and shifting processing is performed.

Next, a lockup determination routine is executed, and if the lockup has been changed, a lockup processing routine is executed to perform lockup processing. Here, engine brake control is performed as part of the lock-up process. Here, when the throttle opening is fully closed (idle contact on) and the vehicle speed is above the set vehicle speed (15 km/h), the frontage pull-up solenoid is turned on and directly connected to the engine rotation speed and turbine rotation speed, which are related to the shift stage. Apply engine brake. After 0.6 seconds have elapsed in the state where the idle contact is off or the engine speed>turbine speed, a gear change is determined based on the gear position at that time.

Next, a walking speed control routine is executed,
Walking speed control is performed (step 63)
. Walking speed control speeds the vehicle up to approximately 3 km/h.
This is a constant speed traveling mode in which the vehicle travels at a constant speed of h.

It can be used when the vehicle and the worker outside the vehicle are working while moving. It is activated when the driver turns off the brake and turns on the walking switch. Line pressure control and 1.
Shifting between 5T and 2NO is performed in combination. If the above condition disappears and the driver opens the throttle by 1/4 or more or turns on the foot brake, 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 to perform output control (step 65).

(Interrupt routine) The outputs of the output shaft rotation sensor, turbine rotation sensor, and engine rotation sensor are each connected to the interrupt input terminal of the central processing unit 7 CPU, and each time the voltage level of the interrupt terminal changes, the output Shaft rotation sensor interrupt routine, turbine rotation sensor interrupt routine,
An engine rotation sensor interrupt routine is executed.

In the output shaft rotation sensor interrupt routine, first, the time at the time of the interrupt is read from a timer, and then a calculation flag for calculating the output shaft rotation speed is turned on. Next, determine the failure of the turbine rotation sensor and engine rotation sensor (
Steps 66-68). This failure determination is performed by comparing the output shaft rotation speed, the turbine rotation speed, and the engine rotation speed.

In the turbine rotation sensor interrupt routine, first, the time at the time of the interrupt is read from a timer, and when the interrupt is counted four times in order to divide the input pulse into four, an arithmetic flag for calculating the turbine rotation speed is turned on. Then, a failure of the engine rotation sensor and the output shaft rotation sensor is determined (steps 69 to 7.1). This failure determination is performed by comparing the turbine rotation speed, engine rotation speed, and output shaft rotation speed.

Incidentally, the frequency division may be performed by installing a frequency division circuit between the central control unit 1-CPU and the rotation sensor.

In the engine rotation sensor interrupt routine, first, the time at the time of the interrupt is read from a timer, and when the interrupt is counted 8 times in order to divide the input pulse by 8, a calculation flag for calculating the engine rotation speed is turned on. Then, a failure of the output shaft rotation sensor and the turbine rotation sensor is determined (steps 72 to 74). This failure determination is performed by comparing the engine rotation speed, the output shaft rotation speed, and the turbine rotation speed.

Incidentally, 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 regular interrupt that occurs every predetermined period of time. In this example, 4I
A scheduled interrupt routine is executed every II8. Here, first, various timers used for control are subtracted (step 75).

Next, it is determined whether the vehicle has stopped (step 76). In this example, vehicle stopping speed N5top=l 44r
pm (approximately 3 km) or less. In addition, the input frequency T S top to the CPU (central control unit)
23. When there is no pulse of 13m5 or more, the vehicle is stopped.

The details of each control will be explained below based on the flowchart.

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

(Line pressure control) First, read the throttle opening data obtained in the input signal reading routine, search the turbine rotation range from the turbine rotation speed NT, and find the line pressure from the turbine rotation range and throttle opening data T II R ( Step 14
8-150). The line pressure is determined from the line pressure map shown in FIG. The line pressure map shown in FIG. 7 is obtained from actual measurements. The line pressure at which the efficiency during shifting becomes better than the actually measured value is as shown in FIG. 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 will be described later, when the walking flag that is turned on during walking speed control is off, the obtained duty value is output and the line pressure control solenoid valve 48 is driven (steps 152 and 153). Thereby, the line pressure is controlled to the determined value. Next, the line pressure base number is determined from the determined line pressure (step 154). The line pressure base number is obtained by dividing the line pressure between the lowest value and the highest value into eight equal parts, and makes it easy to use other controls using line pressure.

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

If the throttle opening is large, the brake switch is on (intention to stop), or the walking switch is off, the walking timer and walking shift timer are cleared (steps 257, 258).

When the walking switch is on, if the walking flag is not on and the vehicle speed is less than 3 km/h, the walking flag is turned on, 2nd is sent to the output cover sofa, and 2nd is engaged with a duty of 60%. (Steps 259-263). Then, a walking timer and a walking shift timer are started (steps 264, 265).

When the walking switch 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 walking shift timer has not finished and the walking timer has finished, the walking timer is started and the line pressure is set to 8.
kg/cm! If it is not above, change the line pressure data to 2.
kg/cnl, the line pressure control solenoid valve 48 is controlled (steps 266 to 272).
). When the value of the output cover sofa is 2nd and the walking shift timer has ended, the walking shift timer is cleared, the 1st is sent to the output cover sofa, and the 1st is engaged with a duty of 60% (
Steps 273-277). Then, a walking timer is started (step 277).

When the walking switch is on, the walking flag is on, and the vehicle speed is 4 km 76 or higher, the following operation is performed. First, clear the walking shift timer. Next, the vehicle speed is 6 to 7 k+a
/ h and when the walking timer ends, the line pressure is lowered by 0.5 kg/cd and the walking timer is started (steps 279, 284 to 28
7). When the vehicle speed is 7 ka+/h or more, when the walking timer ends, and the line pressure is not at the lowest limit, the line pressure is increased or decreased by 1 kg/cd and the walking timer is started (steps 279 to 283).
).

In this way, the line pressure of the hydraulic circuit is changed according to the vehicle speed, lowering the line pressure when the vehicle speed is high and increasing the line pressure when the vehicle speed is low. As a result, at high vehicle speeds, the engagement of the clutch or brake that is currently engaged in the automatic transmission is weakened, resulting in a state close to neutral. Therefore, the speed of the vehicle decreases on a normal flat road. At low vehicle speeds, the engaged clutch or brake of the automatic transmission is reliably engaged, so the driving torque of the engine is reliably transmitted to the wheels, increasing the vehicle speed. Therefore, the speed of the vehicle is kept approximately constant.

Also, at the start of control, the gear stage is shifted to 2nd -L,
This suppresses the increase in vehicle speed. In this state, the walking shift and timer have finished, and the vehicle speed is 4 km/h.
This continues until the value becomes less than h, and then returns to ISt.

〔Effect of the invention〕

As explained above, according to the present invention, there is provided an automatic transmission having a clutch and a brake that are operated by application of fluid pressure and changing a gear ratio by engaging and disengaging the clutch and the brake. Fluid pressure switching means for independently controlling the application of fluid pressure to the brakes, and driving the fluid pressure switching means depending on the running state of the vehicle to change engagement/disengagement of the clutch and the brake. an electronically controlled automatic transmission comprising electronic control means;
In a speed control device comprising vehicle speed detection means for detecting the speed of a vehicle, and pressure control means for controlling fluid pressure to the clutch and brake according to the speed, instructing the pressure control means to start pressure control. Instruction means (34)
The electronic control means drives the fluid pressure switching means (steps 262 to 263) to change the gear to the high speed side in response to an instruction from the instruction means, and then changes the gear to the low speed side. Drive the fluid pressure switching means to change the fluid pressure to (
Steps 275-276).

Therefore, the fluid pressure is changed according to the vehicle speed, and the state of engagement between the engine and the wheels is controlled, so that the speed of the vehicle is kept substantially constant. In this way, the vehicle speed can be adjusted regardless of the opening degree of the throttle valve, for example, even when the throttle valve is fully closed, but since it is possible to prevent the vehicle speed from increasing at the beginning of control, it is possible to stabilize the speed more quickly. can. Furthermore, if the vehicle speed is controlled in accordance with the walking speed of a person, increasing the vehicle speed even temporarily can be dangerous, so this is useful for preventing such danger.

Since the present invention uses an electronically controlled automatic transmission device that has been conventionally used in vehicles, the present invention can be carried out simply by using pressure control means and changing the program, which is economical.

[Brief explanation of the drawing]

FIG. 1 shows an automatic transmission of an electronically controlled automatic transmission which is an 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 that controls the hydraulic circuit of FIG. FIG. 4 is a flowchart of the main routine of the CPU of the electronic control circuit of FIG. 3, a vehicle speed sensor interrupt, a turbine rotation sensor interrupt, an engine rotation sensor interrupt, and a scheduled interrupt. FIG. 5 is a flow chart of line pressure control by 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 among turbine rotational speed, throttle opening, and line pressure in an embodiment of the present invention. CPU... Central processing unit, 20... Battery, 21... Ignition switch, 22... Constant voltage power supply, 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 ・ 33 ・ 34 ・ 40 ・ 4 l ・ 42 ・ 43 ・ 44 ・ 45 ・ 46 ・ BU, 47 ・ 48 ・ B2 ・ C2 ・ B1 ・ CO ・ BO ・ Ct ・ Idle switch, ・ Brake Switch, ・Walking mode switch, ・Walking speed lamp, ・Solenoid pulp for clutch CO control, ・Clutch 0
2 control solenoid valve, ・Solenoid valve for brake 82 control, ・Solenoid valve for brake 82 control, ・Solenoid valve for brake 82 control, ・Solenoid valve for low and reverse inhibition, solenoid valve for pulse lock-up control, solenoid for line pressure control Valve, 1st and Rev brake, direct clutch, 2nd brake, OD clutch, OD brake, forward clutch, 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, 610.61
9,621... Planetary pinion, 611... Human power shaft, 612... Sun gear, 613... Housing, 614... Intermediate shaft, 615... Sun gear shaft, 701... Oil sump, 702 ... Hydraulic pump, 703 ... Pressure adjustment valve, 704 ... Line pressure oil path, 705.706.707, 708, 709 ... Manual valve, 710 ... Valve, ■ Shift valve, 0tsuk Up control valve.

Claims (1)

[Scope of Claims] An automatic transmission having a clutch and a brake operated by applying fluid pressure, and changing a gear ratio by engaging and disengaging the clutch and brake; A fluid pressure switching means for independently controlling application of fluid pressure, and an electronic control means for driving the fluid pressure switching means and changing engagement/disengagement of the clutch and brake according to the running state of the vehicle. an electronically controlled automatic transmission; a vehicle speed detection means for detecting the speed of the vehicle;
A speed control device comprising a pressure control means for controlling fluid pressure to the clutch and brake according to the speed, further comprising an instruction means for instructing the pressure control means to start pressure control, the electronic control means driving the fluid pressure switching means to change the gear to a high speed side in response to an instruction from the instruction means, and then driving the fluid pressure switching means to change the gear to a low speed; Speed control device.