JPS6151183B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic transmission control device for a construction vehicle such as a bulldozer, and more particularly to an automatic transmission control device having a function of preventing malfunction of an automatic transmission.

Unlike general vehicles, construction vehicles are operated in very severe environments and operating conditions, and the handling and service capabilities of users, operators, and service personnel vary depending on the region and country. Problems and problems that appear are occurring in ways that would normally be unimaginable.
With conventional automatic transmission control systems, the above-mentioned situations were not fully understood and countermeasures against them were insufficient, resulting in system safety issues.
This led to a decline in reliability.

This invention was made in view of these points, and based on past experience, etc.
The present invention provides an automatic transmission control device that is equipped with safety functions that can deal with possible malfunctions, dangers, etc., with sufficient consideration given to service capabilities and the like. Particularly, in this invention, operation of the automatic transmission contrary to operator operation is detected and a solenoid valve driving the automatic transmission is turned off to prevent malfunction of the vehicle and damage to the transmission.

The present invention will be described in detail below based on an embodiment of the accompanying drawings.

FIG. 1 schematically shows an automatic transmission control device to which the present invention is applied.

In FIG. 1, an automatic transmission 1 has a lock-up device that locks a torque converter and directly drives it, and includes a torque converter 3 driven by an engine 2 and a torque converter 3 that decelerates the rotation transmitted from the torque converter 3. The transmission includes a transmission 4 that transmits information to the drive wheels, and a solenoid valve that changes the gear position of the transmission 4.
The microcomputer 6 operates based on the operation position of the gear select lever 7 by the operator, the depression angle of the accelerator pedal 9 detected by the throttle sensor 8, the rotation speed of the torque converter output shaft 11 detected by the torque converter rotation sensor 10, etc. The optimum gear position is selected by calculation, the solenoid valve 5 is driven, and the transmission 4 is switched. This microcomputer 6 applies voltage from a battery 12 via a key switch 13 as a power source.

The solenoid valve 5 consists of multiple pieces,
The gear position to be engaged is determined depending on the combination of these. FIG. 2 shows an example of the combination. In other words, Fig. 2 shows 8 gears (1 reverse gear (R), neutral (N), 6 forward gears (P ₁ to _{P 6} )).
Yes, this is 5 solenoid valves SOL1~
This is an example of driving with SOL5, and the valves that are turned on at each gear stage are indicated by O marks.

For example, when the select lever 7 is in range _P3 and the vehicle is running in second forward speed, when the accelerator 9 is set to full throttle, the rotation of the torque converter 3 increases. When the rotation exceeds, for example, 1950 rpm, solenoids SOL3 and SOL4 are turned on and the gear is automatically switched to third speed. When switching to 3rd gear, the load is temporarily large and the rotation speed drops, but if you continue to press the accelerator 9, the speed will exceed 1950 rpm again. Then, only solenoid SOL3 turns on and automatically shifts up to 4th gear. Conversely, when you release the accelerator and the rotation drops to 1200rpm, solenoid SOL3 and SOL
4 turns on and automatically shifts down from 4th gear to 3rd gear. In this way, it is possible to automatically shift up or down to the gear most suited to the driving conditions of the vehicle.

In the above-mentioned automatic transmission control device, a forward command and a reverse command may be issued at the same time due to a malfunction of the microcomputer 6. In such a case, the transmission body may malfunction or the vehicle may run in the opposite direction to the one operated. It is extremely dangerous. Therefore, in the present invention, when a forward command and a reverse command are issued at the same time by utilizing combinations of solenoid valves at each gear stage, all related solenoids are turned off to ensure safety. To explain according to the example in Fig. 2, the reverse drive is created by a combination of solenoids SOL1 and SOL4, and the forward drive is created by a combination of solenoids SOL2, SOL3, SOL4,
Made with a combination of SOL5, especially solenoid
One of SOL2, SOL3, and SOL5 is always on when moving forward. Therefore, when forward drive and reverse drive commands are issued at the same time, solenoid SOL1
This means that one or more of solenoids SOL2, SOL3, and SOL5 are on. In the present invention, by detecting such a state, the solenoid is turned off to prevent forward drive and reverse drive from being engaged at the same time.

A circuit for implementing the above function is shown in FIG.

In Figure 3, solenoid valve SOL2,
Only one of SOL3 and SOL5 is always turned on during forward drive, and solenoid valve SOL1
is turned on only when driving in reverse (second
(see figure). Each solenoid valve SOL2, SOL3,
SOL5 and SOL1 are respectively connected to transistors Tr ₂ , Tr ₃ , Tr ₅ , and Tr ₁ within the transistors driven by the output of the microcomputer, and when operating normally, these transistors Tr ₂ are connected to each other by each drive command. , Tr ₃ , Tr ₅ , and Tr ₁ are turned on and connected to ground, respectively, thereby being energized.

In addition, the above solenoid valve SOL2, SOL
3. SOL5 is a high resistance resistor R2, R3, R
5 to the NAND circuit 20, and the NAND circuit 20 connects these solenoid valves SOL
When any one of SOL3, SOL5 is turned on, the corresponding input becomes low level and outputs a high level signal. Further, the solenoid valve SOL1 is input to the inverter 21 via a resistor R1 having a high resistance value, and the inverter outputs a high level signal when the solenoid valve SOL1 is turned on.

The outputs of the NAND circuit 20 and inverter 21 are applied to a NAND circuit 22. Therefore, the NAND circuit 22 outputs a low level signal when both inputs are at high level, that is, when forward drive and reverse drive are input at the same time. The output of the NAND circuit 22 is connected to the reversely connected diode 2 via the amplifier 23.
Join 4.

A voltage is applied to the anode of the programmable union transistor 31 (hereinafter simply referred to as PUT) from the outside via a resistor 25. Further, a voltage is applied to the gate via the resistor 26. This gate voltage is applied to the diode through the resistor 27 in the forward direction. A Zener diode 28 is connected to the resistor 25, and a resistor 29 is further connected and grounded. The voltage between the Zener diode and resistor 29 is applied to the base of transistor 30. Therefore, when the output of the amplifier 23 is at a low level, that is, when an abnormal operation occurs, current flows from the power supply Vcc into the amplifier 23 through the resistor 26, the resistor 27, and the diode 24, and the PUT 31 is thereby turned on. As a result, the resistor 25 is grounded, the Zener diode 28 is turned off, and the transistor 3
0 is also turned off. Furthermore, when the output of the amplifier 23 is at a high level, that is, when it is operating normally, the diode 24 is not conductive, so the PUT 31 is in an off state. Therefore, the Zener diode is turned on and the transistor 30 is also turned on.

The collector of transistor 30 is transistor 3
Connected to the base of 2. transistor 32
The collector of each solenoid valve SOL2,
Transistors Tr ₂ , Tr ₃ , Tr ₅ , whose collectors are connected to the SOL3, SOL5, and SOL1 connection lines,
Each is connected to the base of Tr ₁ . Therefore, when transistor 30 is turned off (if it operates abnormally), transistor 32 is turned off, and transistors Tr ₂ , Tr ₃ , Tr ₅ and Tr ₁ are turned off. When transistors Tr ₂ , Tr ₃ , Tr ₅ , and Tr ₁ are turned off, solenoid valves SOL2, SOL3, SOL5, and SOL1 are all turned off. Furthermore, when the transistor 30 is turned off (if it operates normally), the transistor 32 is turned on, and the transistors Tr ₂ , Tr ₃ , Tr ₅ , and Tr ₁ are turned on by each drive command.

As described above, when an abnormality occurs, that is, when both forward drive and reverse drive are engaged, the solenoids SOL2, SOL3, SOL5, and SOL1 are forcibly turned off, and the drive of the automatic transmission 1 is stopped.

As explained above, the embodiment shown in Fig. 3 is effective when driving in both directions is engaged during forward or reverse operation, but when the operation is performed in neutral, a malfunction of the microcomputer causes the reverse drive to fail. No action can be taken if the solenoid valve is turned on.

Therefore, in the present invention, even if a solenoid valve drive command for reverse drive is issued from the microcomputer 6, the position of the select lever 7 is reliably set to reverse (R), assuming such a case. If not, the solenoid valve will not be turned on.

An example for implementing the above function is shown in FIG. The circuit shown in FIG. 4 is incorporated into the microcomputer 6 shown in FIG.

Taking the combination of solenoid valves shown in Figure 2 as an example, the reverse drive is performed using the solenoid valves.
This is achieved by turning on SOL1 and SOL4. Here, the solenoid valve SOL1 is not used for forward drive or neutral. Therefore, only for solenoid valve SOL1, the select lever position and drive command are logically summed.
The reverse solenoid valve is turned on only when the two match.

In FIG. 4, the switch 40 is the select bar 7.
It is turned on when the reverse drive position (R) is operated in conjunction with . This reverse select switch 40 is connected to an arithmetic circuit 50 via an inverter 41. Also, before the inverter 41, the power supply Vcc
A voltage is applied from With this configuration, the inverter 41 outputs a low level signal when the reverse select switch 40 is off (when the select lever 7 is in a position other than the reverse position (R)), and when the reverse select switch 40 is on ( When the select lever 7 is in the reverse position (R), the inverter 41 outputs a high level signal. The arithmetic circuit 50 operates the solenoid valves SOL1 and SOL when the output of the inverter 41 is at a high level.
4 drive command (high level signal) is output.

Among the above drive commands, solenoid valve SOL1
The drive command is applied to the NAND circuit 42. The output of the inverter 41 is directly applied to the other input terminal of the NAND circuit 42. Therefore, the NAND circuit 42 outputs a low level signal only when the select lever 7 is reliably selected to the reverse position R and the arithmetic circuit 50 issues a reverse command. Due to a malfunction of the calculation circuit 50, the solenoid valve SOL1 is closed during forward or neutral operation.
Even if the drive command is output, the other input of the NAND circuit 42 remains at the low level at this time, so the NAND circuit 42 does not output a low level signal.

The output of the NAND circuit 42 is applied to the base of a transistor 44 via an amplifier 43. The collector of the transistor 44 is connected to the power supply Vcc via a resistor, and the emitter is grounded. The collector is also connected to the base of another transistor 46 via a diode 45. transistor 4
6 collector has a solenoid valve from the power supply
A voltage is applied via SOL1 and a diode 47, and the emitter side is grounded.
Solenoid valve SOL1 is this transistor 4
6 is turned on, it is turned on.

With this configuration, when the output of the NAND circuit 42 is at a low level (solenoid valve SOL1
(when a normal drive command is issued), the transistor 44 is turned off, the transistor 46 is turned on, and the solenoid valve SOL1 is turned on. Furthermore, when the output of the NAND circuit 42 is at a high level (when an incorrect drive command is issued for the solenoid valve SOL1, or when reverse drive is not selected), the transistor 44 is turned on, and the transistor 46 is turned off. Solenoid valve SOL1
is turned off.

As explained above, according to the present invention, a combination of solenoid valves that are driven only when moving forward and solenoid valves that are driven only when moving backward is selected, and when they try to turn on at the same time, they are forcibly turned off. This prevents dangerous driving contrary to the operation and damage to the transmission. Furthermore, for reverse drive, the corresponding solenoid valve is driven only when the drive command from the microcomputer and the actual operation of the select lever match, so safer driving can be ensured.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing an automatic transmission control device to which the present invention is applied, FIG. 2 is a diagram showing an example of a combination of each shift stage and a solenoid valve to be turned on, and FIG. FIG. 4 is a block diagram showing an example of a control circuit for making reverse drive safer. 1... Automatic transmission device, 6... Microcomputer, 8... Throttle sensor, 7... Select lever, SOL1 to SOL5... Solenoid valve, 50... Arithmetic circuit, 40... Reverse select switch.

Claims (1)

[Claims] 1. In an automatic transmission control device in which each gear stage is switched by a combination of a plurality of solenoid valves, a forward solenoid valve is turned on only when driving forward, and a reverse solenoid valve is turned on only when driving backward. The solenoid valves are divided into separate groups, and both detection means detect that one of the solenoid valves is on in each group. and a means for turning off the gear, and further, when a drive command applied via an arithmetic circuit from a reverse selection switch interlocked with the gear selection lever and a signal directly sent from the reverse selection switch are issued at the same time. and means for turning on the reverse solenoid valve.