JPS62278366A - Speed control system for hydraulic pressure driven vehicle provided with gear type transmission - Google Patents

Abstract

PURPOSE:To avoid shocks upon engagement of a clutch, by making the input and output side rotational speeds of a clutch coincident with each other before engagement of the clutch when a gear type transmission is shifted, and thereafter, by engaging the clutch at the moment at which both rotational speeds coincide with each other. CONSTITUTION:When the driver manipulates a change-over switch 14, the voltage applied to a terminal of a controller 13 varies, and therefore the controller 13 discriminates a speed change instruction. Further in the case of no possibility of speed increasing shift or overrun, a direction control solenoid valve 10 is set at its neutral position, and therefore, all clutches are raced. Further, the difference in rotational speed between the input and output of the clutch is calculated in accordance with signals from rotational speed detectors 6, 7, and therefore, an electrohydraulic control valve 5 is controlled in accordance with the above-mentioned difference to change the displacements of both variable displacement pump 1 and motor 4 by means of serve-valves 2, 3. Further, at the moment at which both input and output rotational speeds coincide with each other, a direction control solenoid valve 10 is actuated to engage the clutches.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Field of Industrial Application) This invention relates to a transmission consisting of a hydraulically driven transmission and a gear transmission. This relates to the control system of the machine (H, S, T) and gear transmission.

(Prior Art) A conventional transmission of this type is shown in FIG. 3. That is, in the figure, A is a hydraulic drive transmission, B is a gear transmission, C is a controller, D is a high/low speed changeover switch, and E is an engine. Therefore, the hydraulic drive transmission A is an H3 that connects a variable displacement pump a and a variable displacement motor b.
It has a T main circuit m, and is equipped with a short circuit pulp d and a load sensing system e. Gear transmission aB has a high speed gear f and a low speed gear g.

h is a clutch pressure switching control valve.

When the high speed/low speed changeover switch D is changed from low speed to high speed, the short circuit valve d is activated (ON) in response to a command from the controller C, and the H, S, and T main circuits m are short circuited. During this short circuit, the low speed clutch of the gear transmission B becomes free and the high speed clutch is engaged. After this high-speed clutch is engaged, the short circuit valve d is turned OFF, and pressure is generated in the main circuit m of the hydraulic drive transmission A, and this pressure automatically sets the discharge amount of the variable displacement motor b. In other words, the discharge amount of the motor is commensurate with the load.

(Problems to be Solved by the Invention) In the conventional device as described above, since there is a difference in relative rotational speed between the clutch input side and the clutch output side when the clutch is engaged, the clutch may generate heat when the clutch is engaged. The hydraulic drive transmission and engine tend to overrun, and the vehicle speed becomes discontinuous before and after the clutch is engaged, which is transmitted to the driver as a shock and causes discomfort to the driver.

(Means and effects for solving the problems) The present invention has been made in view of the above problems, and provides a servo valve for a pump of the hydraulically driven transmission in a transmission consisting of a hydraulically driven transmission and a gear transmission. An electrohydraulic control valve is installed between the motor servo valve and the controller, and an electromagnetic directional control valve is installed between the controller and the gear transmission.

Furthermore, a motor output rotation speed detector and a transmission output shaft rotation speed detector are provided.

When shifting a gear transmission, the clutch is disengaged before the clutch is engaged, and the clutch input and output revolutions are matched to prevent heat generation when the clutch is engaged and to prevent engine overrun. This is what I did.

(Example) Next, an example of the present invention will be described based on the drawings. Figure 1 schematically shows the outline of its configuration. 1 is a variable displacement pump, 2 is a servo valve for the pump, and the pump discharge amount increases in proportion to the controlled oil pressure. There is. 3 is a servo valve for the motor.

As the control oil pressure increases, the discharge amount of the variable displacement motor 4 decreases. 5 is an electrohydraulic control valve, which is a pressure reducing valve that controls the downstream hydraulic pressure to a pressure proportional to the current. 6 is a motor output rotation speed detector, and 7 is a transmission output shaft rotation speed detector. 8 is a high-speed stage piston,
9 indicates a low speed piston. 10 is an electromagnetic directional control valve;
11 is a gear pump, and 12 is a clutch pressure regulating valve. 13 is the controller, 14 is the high (H) low (L) front (
F) Rear (R) forward changeover switch, 15 indicates a power source. Note that N is the variable capacity morph output rotation speed, and No is the transmission output rotation speed.

Now let's talk about (1) clutch synchronization.

When the driver operates the changeover switch 14, the voltage applied to the terminals of the controller 13 changes, and the controller 13 determines a speed change command. In the case of a speed increase shift or a deceleration shift without the possibility of overrun, the controller 13 sets the electromagnetic directional control valve 10 to neutral (N), so that all the clutches idle. and rotation speed detector 6
, 7, the controller 13 is activated.

Calculate the output rotation speed difference (relative rotation speed), and if there is a difference in the relative rotation speed,
A clutch person changes the discharge amount of the variable displacement pump 1 and the variable displacement motor 4.

The electromagnetic directional control valve 10 is activated in accordance with the command from the changeover switch 14 at the moment when the output rotational speeds match.

In this way, before the clutch is engaged, the clutch synchronization action is performed by matching the input side rotational speed with the output side rotational speed.

Next, (2) overrun prevention function will be described. The controller 13 determines the shift command of the changeover switch 14, and when the shift command is a deceleration command, the rotation speed detector 7 detects the output rotation speed of the gear transmission. Based on the rotation speed and gear ratio, the controller 13 determines the possibility of overrun of the hydraulic drive transmission, and if there is a possibility of overrun, controls the electro-hydraulic control valve 5, and controls the variable displacement pump l and the variable displacement The discharge amount of the motor 4 is controlled to decelerate the vehicle to below the overrun limit of the hydraulic drive transmission. The controller 13 performs the clutch synchronization action described in (1) after confirming that there is no overrun using the rotation speed detector 7.

FIG. 2 shows a flowchart of the system operation of the control method of the present invention described above.

As mentioned above, in the embodiment of this invention.

Before engaging the clutch, the clutch input side rotation speed and output side rotation speed are made to match with the clutch disengaged, so there is no relative rotation between the latch input side and output side when the clutch is engaged.
There is no generation of heat such as clutch slippage or relief of the main circuit in the hydraulically driven transmission.

(Effect of the invention) This invention is constructed as described above in detail.

When shifting a gear transmission, it is possible to match the clutch input side rotation speed and output side rotation speed before clutch engagement, so it is possible to eliminate the problem caused by the difference in relative rotation speed between the clutch input and output sides as in the past. Heat generation of the clutch when the clutch is engaged can be prevented, and discontinuity in vehicle speed before and after the clutch engagement, which causes discomfort to the driver, can be completely eliminated.

In addition, by determining the possibility of overrun when shifting in the deceleration direction, and if there is a possibility of overrun, the vehicle speed is automatically reduced to the overrun limit in advance. The occurrence of overrun can be completely prevented.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating the main parts of an embodiment of the present invention, FIG. 2 is a flowchart of system operation according to this method, and FIG. 3 is a conventional device. 1...Variable displacement pump. 2...Servo valve for pump. 3... Servo valve for motor. 4...Variable capacity motor. 5...Electro-hydraulic control valve. 6...Motor output rotation speed detector. 7...Transmission output shaft rotation speed detector. 8... Piston for high speed stage. 9...low speed piston. 10... Solenoid directional control valve, 13... Controller. 14...High/low forward/backward changeover switch.

Claims (1)

[Claims] An electro-hydraulic control valve is provided between the pump servo valve and motor servo valve of the hydraulic drive transmission and the controller, and an electromagnetic directional control valve is provided between the gear transmission and the controller, and the input side of the gear transmission A motor output rotation speed detector that detects the output side of the gear transmission and a transmission output shaft rotation speed detector that detects the output side of the gear transmission are provided respectively. A speed control method for a hydraulically driven vehicle with a gear transmission, characterized in that the rotation speed on the output side is made to match the rotation speed on the output side.