JPH0550237U - Shift control device for multi-shift hydraulic motor - Google Patents

Abstract

(57) [Abstract] [Purpose] A hydraulic construction machine equipped with a traveling transmission device has a smooth start-up when starting traveling at a "high speed" position to improve operability. [Structure] A pressure switch 36 is inserted in series with a manual shift switch 35 for operating a solenoid valve 33 for shifting. Signal passages 45 and 46 are provided in the spools 39 and 40 of the directional control valves 25 and 26 that control the hydraulic motors 21 and 22, respectively. The signal passages 45, 46 close the opening with a constant spool stroke. The hydraulic pressure source 38 is branched and connected to the signal passages 45 and 46 and the pressure switch 36. Operating levers 31, 32
The pilot pressure is not applied to the pressure switch 36 within a certain range from the neutral position. Therefore, the manual transmission switch 35
Even if the switch is turned on, the control current is not output to the solenoid valve 33 at the time of startup, and the hydraulic motors 21 and 22 are "low speed".
Starting with, the speed is changed to "high speed" with a predetermined operation amount.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a shift control device for a multi-speed hydraulic motor, and more particularly to a shift control device having improved starting characteristics when "high speed" is set.

[0002]

[Prior Art]

 A conventional shift control device for a multi-speed hydraulic motor will be described with reference to FIGS. FIG. 4 shows a hydraulic motor drive circuit for running a construction machine such as a hydraulic excavator. Two hydraulic motors 1 and 2 that drive the left and right crawlers separately are supplied with hydraulic oil from hydraulic pumps 5 and 6 via directional control valves 3 and 4, respectively. The directional control valves 3 and 4 are controlled by the remote control valves 7 and 8, and the opening areas of the directional control valves 3 and 4 are controlled in proportion to the operation amounts of the operation levers 9 and 10 to stop the hydraulic motors 1 and 2 from stopping. You can change the maximum speed.

The hydraulic motors 1 and 2 have speed switching pistons 11 and 12 incorporated therein, and can switch the rotational speed range between two stages of “low speed” and “high speed”. The speed is switched by the manual shift switch 13. When the manual shift switch 13 is turned on, the solenoid valve 14 is switched from the A position shown in the figure to the B position. As a result, pressure oil is supplied from the hydraulic power source 15 to the speed switching pistons 11 and 12, and the hydraulic motors 1 and 2 are switched from "low speed" to "high speed". When the manual transmission switch 13 is turned off, the solenoid valve 14 returns to the A position, the speed switching pistons 11 and 12 communicate with the tank 16 to release the pressure oil, and the hydraulic motors 1 and 2 move to "low speed". Return.

FIG. 5 shows an example of the relationship between the operating lever displacement and the traveling speed at “low speed”. When the operating levers 9 and 10 are rotated by 20%, the aircraft starts traveling and the maximum speed is It is about 4 km / h. FIG. 6 is an example at “high speed”, and since the hydraulic pressure required for starting is higher than at “low speed”, the dead zones of the operating levers 9 and 10 are about 40%. Immediately after starting, the running speed increased to about 2 km / h, and the maximum speed was about 6 km / h.

[0005]

[Problems to be solved by the device]

 The hydraulic pressure required for starting up a construction machine or the like equipped with the above-described conventional hydraulic motor drive circuit for traveling is higher in “high speed” than in “low speed”. Therefore, at "high speed", the dead zone of the operation lever is wide, and as shown in Fig. 6, it is difficult to start smoothly due to a sudden change from stationary to running, and it is not possible to run at a low speed or move a small distance. It's not easy.

Therefore, there is a technical problem to be solved in order to enable smooth startup even from the state of being set to the “high speed” side and improve operability and workability. The present invention solves this problem. The purpose is to do.

[0007]

[Means for Solving the Problems]

 This invention is proposed in order to solve the above-mentioned problems. In a transmission of a multi-speed hydraulic motor, in which a solenoid valve is operated by a manual speed change switch to change the speed switching piston of the hydraulic motor, An operation amount detector is provided in the operation system of the above, a switch is provided in the control signal line to the solenoid valve, and the switch is controlled by the operation amount detector, and a certain operation amount is set as the opening and closing operation point of the switch. In addition to setting, a logical circuit is formed by the switch and the manual speed change switch, and when the operation amount is below a certain value, the speed change piston is held at the low speed position regardless of the state of the manual speed change switch. A shift control device for a multi-speed shift hydraulic motor formed as described above is provided.

[0008]

[Action]

 When the operation lever is in the neutral position, the detected operation amount of the operation amount detector is zero. For example, a normally open type manual shift switch is used, and a secondary pressure detector of the operating system or a stroke detector of the operating lever is used as the operation amount detector, and the normally open type pressure switch or normally open type is used. If an AND circuit is configured by connecting a manual transmission switch to this pressure switch or relay in series, the pressure switch or relay will be turned off when the operating lever is in the neutral position, and the manual transmission switch No control current is output to the solenoid valve regardless of whether it is on or off. Therefore, the hydraulic motor is kept at "low speed".

When the operation amount of the operation lever exceeds a preset amount, the pressure switch or the relay is turned on. At this time, if the manual transmission switch is in the “low speed” position of off, the control signal output is off. As is, the hydraulic motor is "low speed". On the other hand, when the manual shift switch is on and “High speed” is selected, if the operation amount of the operation lever exceeds the set amount, the pressure switch or relay turns on and the control current is supplied to the solenoid valve. The speed is changed from "low speed" to "high speed". That is, even when the manual shift switch is set to "high speed", a certain range from the neutral position of the operating lever is maintained at "low speed", and the "high speed" is automatically set when the operation amount exceeds a predetermined amount. Shifts to "," which enables smooth start-up and fine speed running when "High speed" is set.

[0010]

【Example】

 An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a hydraulic motor drive circuit for traveling a hydraulic excavator. The traveling hydraulic motors 21 and 22 are switched to "high speed" by pressure-feeding the pressure oil to the built-in speed switching pistons 23 and 24. If the supply of the pressure oil to the speed switching pistons 23 and 24 is cut off, Return to "low speed". The hydraulic motors 21 and 22 are connected to the hydraulic motors 27 and 28 via the direction control valves 25 and 26. The directional control valves 25 and 26 are controlled by remote control valves 29 and 30, and the remote control valves 29 and 30 generate a pilot pressure proportional to the operation amount of the operation levers 31 and 32 to operate the operation levers 31 and 32. The rotation speeds of the hydraulic motors 21 and 22 are controlled by associating the amount with the spool movement amount of the direction control valves 25 and 26.

The speed switching pistons 23 and 24 of the hydraulic motors 21 and 22 are switched by a solenoid valve 33, and a manual shift switch 35 and a pressure switch 36 are provided between a solenoid 33 a of the solenoid valve 33 and a power source 34. Are inserted in series. The pressure switch 36 is turned on when the pilot pressure is supplied from the hydraulic pressure source 38 through the pilot oil passage 37.

The spools 39 and 40 of the directional control valves 25 and 26 are provided with signal passages 45 and 46, respectively, which connect the inlet ports 41 and 42 and the outlet ports 43 and 44 in a neutral position. The openings of the signal passages 45 and 46 are closed when the spools 39 and 40 are moved from the neutral position by a certain amount. The hydraulic power source 38 is connected to one inlet port 41, the outlet port 43 is connected to the inlet port 42 of the other signal passage 46 via the oil passage 47, and the outlet port 44 thereof is connected to the tank 48. .. The oil passage 49 of the oil pressure source 38 is connected to the above-mentioned inlet port 41 and the pilot oil passage 37 to the pressure switch 36.

Next, the operation of this device will be described. When the manual transmission switch 35 is turned off, the solenoid 33a of the solenoid valve 33 is not energized regardless of whether the pressure switch 36 is on or off, and the solenoid valve 33 is fixed at the position A by the offset of the spring 33b. Therefore, the speed switching pistons 23 and 24 communicate with the tank 50, pressure oil is not supplied to the speed switching pistons 23 and 24, and the hydraulic motors 21 and 22 are set to "low speed". When the operation levers 31 and 32 are in the neutral position, the directional control valves 25 and 26 are also in the neutral position, and the oil discharged from the hydraulic pressure source 38 passes through the signal passage 45 of the directional control valve 25 on the left side in the figure and the right direction. The signal passage 46 of the control valve 26 returns to the tank 48. Therefore, the pilot pressure is not applied to the pressure switch 36, and the pressure switch 36 is off.

When the operation levers 31 and 32 are rotated, the spools 39 and 40 of the direction control valves 25 and 26 are interlocked with each other, and the signal passages 45 and 46 are closed when the spools 39 and 40 are moved from the neutral position by a predetermined amount. As a result, the communication between the hydraulic pressure source 38 and the tank 48 is cut off, the pilot pressure is applied to the pressure switch 36 to turn it on, but the solenoid 33a of the solenoid valve 33 is not energized because the manual transmission switch 35 is off. , The hydraulic motors 21 and 22 maintain "low speed".

On the other hand, even when the manual transmission switch 35 is turned on and “high speed” is selected, the oil discharged from the hydraulic power source 38 is returned to the tank 48 and the pressure switch 36 is turned off as in the case of turning off when stopped. It is off, and the hydraulic motors 21 and 22 are set to "low speed". When the operation levers 31, 32 are gently rotated from the neutral position, the hydraulic pumps 27, 28 and the hydraulic motors 21, 22 communicate with each other as the spools 39, 40 of the directional control valves 25, 26 move. The hydraulic motors 21 and 22 are driven. At this time, since the inlet / outlet ports 41, 42, 43, 44 of the signal passages 45, 46 provided in the direction control valves 25, 26 are not closed within a certain range from the neutral position, the pilot pressure is not applied to the pressure switch 36. However, the hydraulic motors 21 and 22 maintain the "low speed" state.

Then, when the spools 39, 40 move in accordance with the operation amounts of the operation levers 31, 32 and the inlet / outlet ports 41, 42, 43, 44 of the signal passages 45, 46 are closed, the pressure switch 36 is driven by the pilot pressure. Is turned on, and the manual transmission switch 35 is also turned on, so that the solenoid 33a of the solenoid valve 33 is energized, and the solenoid valve 33 is switched from the position A to the position B shown in FIG. As a result, pressure oil is supplied from the hydraulic power source 50 to the speed switching pistons 23, 24, and the hydraulic motors 21, 22 are shifted to "high speed".

FIG. 2 is a graph showing the operation amounts of the operation levers 31 and 32 and the traveling speed. When the “high speed” is set, the operation levers 31 and 32 are set so that the signal passages 45 and 46 are gradually closed. When the vehicle is gently started, the vehicle starts traveling at "low speed" Lo and automatically shifts up to "high speed" Hi with a predetermined operation amount (C) for closing the signal passages 45, 46. Further, if the operating levers 31 and 32 are rapidly operated to instantly close the signal passages 45 and 46, the same starting characteristic as that of the conventional example shown in FIG. 6 can be obtained.

The present invention is not limited to the above-described embodiment, and the configuration of the logic circuit including the manual transmission switch 35 and the pressure switch 36 is not limited to this embodiment. For example, as shown in FIG. 3, a normally closed manual transmission switch 51 and a normally closed pressure switch 52 may be connected in parallel, and a circuit or the like via an inverter 53 may be used. Although not shown, the solenoid valve 33 is omitted. Further various modifications are possible including the configuration of. Further, a pressure sensor or the like for detecting the secondary pressure of the remote control valve may be used as the operation amount detecting means. Furthermore, a sensor that detects the stroke of the operating lever and a relay that replaces the pressure sensor may be used. And it goes without saying that this invention extends to those modifications.

[0019]

[Effect of the device]

 Since the present invention is configured as described in detail in the above-described one embodiment, even when the manual speed change switch is set to "high speed", it starts at "low speed" at the time of very slow operation, and " Upshifted to "high speed". Therefore, it is possible to operate at a very low speed while it is set to "high speed", and the start-up is also smooth, which makes it easy to operate in a small amount, and the operability is remarkably improved, contributing to improved work efficiency. It is an invention.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a shift control device according to an embodiment of the present invention.

FIG. 2 is a graph showing shift points of the shift control device.

FIG. 3 is a logic circuit diagram in another embodiment.

FIG. 4 is a circuit diagram showing a conventional transmission.

FIG. 5 is a graph showing the relationship between the operation amount and the traveling speed at “low speed”.

FIG. 6 is a graph showing the relationship between the operation amount and the traveling speed at the time of the conventional “high speed”.

[Explanation of symbols]

 21, 22 Hydraulic motor 23, 24 Speed switching piston 25, 26 Directional control valve 31, 32 Operating lever 33 Electromagnetic valve 35 Manual transmission switch 36 Pressure switch 38 Hydraulic power source 39, 40 Spool 41, 42 Inlet port 43, 44 Outlet port 45 , 46 Signal passage 48 Tank 51 Manual transmission switch 52 Pressure switch 53 Inverter

Claims (1)

[Scope of utility model registration request] 1. A multi-speed hydraulic motor transmission in which a solenoid valve is operated by a manual transmission switch to switch a speed switching piston of the hydraulic motor, and an operation amount detector is provided in an operation system of the hydraulic motor. A switch is provided in the control signal line to the solenoid valve, the switch is controlled by the operation amount detector, a constant operation amount is set as an opening / closing operation point of the switch, and a logic circuit is provided by the switch and the manual transmission switch. And a shift control device for a multi-stage shift hydraulic motor configured to hold the speed switching piston at a low speed position regardless of the state of the manual shift switch when the operation amount is equal to or less than a certain value.