JP3190998B2 - Hydraulic transmission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic transmission device, and more particularly to a hydraulic transmission device directly connected to a drive shaft of an engine used in an environment affected by the outside air temperature such as a civil engineering machine or a construction machine.

[0002]

2. Description of the Related Art A hydraulic transmission device (hereinafter referred to as H
The ST device is a device that automatically shifts gears using a hydraulic circuit, is connected to a drive shaft of a prime mover such as a diesel engine, and extracts power of a predetermined rotation direction and a predetermined rotation speed from an output shaft. It is. Although the HST device may be connected to the drive shaft of the engine via a clutch,
In recent years, applications using hydraulic drive devices have increased,
In many cases, the HST device is directly connected to the drive shaft of the engine due to good controllability of the hydraulic pressure.

[0003]

However, when starting the engine in cold weather, the direct connection type HS
In the case of the T device, there has been a problem that the starting performance of the engine is reduced. Further explanation will be given. In cold weather, the viscosity of the oil increases, so the driving torque of the hydraulic pump increases even in a no-load state. In this case, in the configuration in which the HST device is connected via the clutch, the clutch can be disengaged at the time of starting the engine, so that the HST driving torque does not affect the startability of the engine. Since the increase in the drive torque of the hydraulic pump at the time of the low temperature is directly applied to the drive shaft of the engine, the starting performance of the engine is reduced.

[0004] Since working machines such as civil engineering machines and construction machines are often used outdoors, the driving torque of the hydraulic pump at the time of starting in a severe cold season is significantly increased. Therefore, in a working machine employing a direct-connection type HST device, the startability at an extremely low temperature (for example, -15 ° C. or lower) is extremely severe.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide an HST device in which the driving torque of a hydraulic pump at a low temperature is reduced to enhance the engine startability.

[0006]

According to a first aspect of the present invention, there is provided an HST apparatus directly connected to a drive shaft of an engine.
Hydraulic pump, output shaft and HST closed
A motor interlocked with the hydraulic pump by a circuit;
Including the hydraulic transmission device, some of the oil
Is a free-flowing oil pipeline from the gap in the hydraulic pump and motor.
To leak into the pump-motor communication circuit of
Pump-motor communication circuit is a hydraulic pump free inflow oil port
To connect the motor and the oil leak port of the motor.
A hydraulic oil heater is provided in the pump-motor communication circuit, and the hydraulic oil heater is driven in response to activation of the engine preheating device.

[0007] The HST device according to claim 2, work machine en
Hydraulic transmission device directly connected to the drive shaft
In the free-flow oil circuit, the free-flow oil inlet port of the hydraulic pump
In addition to installing a hydraulic oil heater near the
A free-flow oil return line that drives the hydraulic oil heater in response to the activation of the preheating device and recovers free-flow oil from the free-flow oil outlet port of the hydraulic pump to the oil tank via a heat exchanger; Free-flow oil supply line that supplies oil to the hydraulic pump again by the charge pump, and a bypass line that connects the free-flow oil return line and the free-flow oil supply line without passing through a heat exchanger and an oil tank. And a three-port switching valve provided at a communication portion between the bypass pipeline and the free-flow oil supply pipeline, wherein the flow of the free-flow oil is switched to the bypass pipeline during a predetermined period.

[0008]

According to the first aspect of the present invention, the pump mode
It provided with a hydraulic oil heater data communication in the circuit, since in correspondence with the activation of the preheating device of an engine for driving the hydraulic oil heater, pump over motor communicating when activating the preheating device
The temperature of the oil in the circuit can be raised quickly. Therefore, when the engine is started in cold weather, the driving torque can be forcibly reduced, the time until the engine self-sustained rotation can be significantly shortened, and the starting performance can be improved.

In the HST device according to the second aspect, the provision of the bypass pipe line prevents the supply of new oil having a low temperature from the oil tank to the hydraulic pump, and the hydraulic oil from the hydraulic pump. Can be sucked into the charge pump again. As a result, the working oil that has been circulated once and the temperature of which has increased can be used repeatedly, so that the temperature increase can be promoted and the starting performance can be further improved. Note that the driving period of the preheating device and the driving period of the starter can be exemplified as the predetermined period.

[0010]

As described above, according to the first aspect of the present invention, the following specific effects can be obtained. (A) When starting the engine in cold weather, the driving torque of the hydraulic pump can be reduced. Therefore,
The starting performance can be improved and the starting limit temperature can be lowered.

(B) Since it can be realized only by adding a hydraulic oil heater in the hydraulic circuit without changing the hydraulic pump or the like of the HST device, the application range is wide and it can be implemented at low cost. According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, the hydraulic oil which has been circulated once and the temperature of which has been increased can be used repeatedly. It has a specific effect that it can be performed.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a schematic hydraulic circuit diagram for explaining an embodiment of the HST device according to the present invention.

The HST device 1 includes a drive shaft 1 of an engine.
Variable pump 2 directly connected to HST 2 and HST closed circuit 3
And a constant displacement motor 4 interlocked with the motor.
The variable displacement pump 2 includes a movable swash plate 6 whose inclination angle changes when the control handle 5 is driven in the direction A in the drawing. By driving the control handle 5, a pair of pins 8, 8 for driving the movable swash plate 6 by the swash plate drive oil passage 7 is moved, and the inclination of the movable swash plate 6 is changed.

The variable displacement pump 2 has a plurality of pistons 1 supported on a movable swash plate 6 by a thrust plate.
0 are provided, and the pistons 10 are inserted into the cylinder block 11. The cylinder block 11 is connected by a HST closed circuit 3 to a pair of motor kidney ports from a pair of pump kidney ports.

The fixed displacement motor 4 is provided with a plurality of pistons 16 supported on a fixed swash plate 15 by a thrust plate.
It is inserted in. The output shaft 18 integrated with the cylinder block 17 is configured to rotate in a predetermined direction by oil supplied from the HST closed circuit 3.

The variable displacement pump 2 and the fixed displacement motor 4 are connected by an HST closed circuit 3, and most of the oil is H
It is circulating in the ST closed circuit 3. Some oil functions as lubricating oil for the variable displacement pump 2 and the constant displacement motor 4 and leaks into the free flowing oil circuit from a gap in the variable displacement pump 2 and the fixed displacement motor 4. Therefore, a charge pump 22 for replenishing oil from the oil tank 21 into the HST closed circuit 3 is provided in the free flowing oil circuit.

The free-flowing oil circuit includes a free-flowing oil supply circuit 19 and a pump-motor communication circuit 20 in the configuration shown in FIG. The free-flow oil supply circuit 19 includes an oil supply pipe 24 that supplies oil from an oil tank 21 to the HST closed circuit 3 via a charge pump 22, and a hydraulic oil in the variable displacement pump 2 for the variable displacement pump 2. An oil return line 27 for collecting oil from the oil leak port 25 to the oil tank 21 via the oil cooler 26; a predetermined position of the oil return line 27 upstream of the oil cooler 26; And a bypass line 30 communicating with a predetermined position of the oil supply line 24 on the more upstream side. A three-port electromagnetic solenoid valve 31 is provided at a communication portion between the bypass line 30 and the oil supply line 24.
An oil filter 32 is interposed between the three-port electromagnetic solenoid valve 31 and the oil tank 21.

The pump-motor communication circuit 20 is a free-flow oil line connecting the oil inlet port 33 of the variable displacement pump 2 and the oil leak port 34 of the constant displacement motor 4. A hydraulic oil heater 35 is provided at a position closer to the pump 2. Various relief valves 40 are provided at predetermined positions of the HST device 1.

FIG. 2 is a schematic control circuit diagram of a characteristic portion of the HST device according to the present embodiment. This device is configured to apply a voltage from a battery 45 to a starter 47 via a starter switch 46 and to a glow plug 49 via a glow switch 48, respectively. Further, a hydraulic oil heater 35 and a solenoid 59 of the three-port electromagnetic solenoid valve 31 are connected in parallel with the glow plug 49, respectively. The starter switch 46
When the is short-circuited, the glow switch 48 is automatically short-circuited. In FIG. 2, the free flowing oil supply circuit 19 is schematically shown in a frame 55.

The operation of the HST device having the above configuration will be described. When the operator operates the control handle 5 in a predetermined direction to drive the movable swash plate 6, the power of the drive shaft 12 as an input shaft is output to the output shaft 18 at a predetermined rotation speed in a predetermined rotation direction. Since the shifting operation of the HST device is well known, a detailed description thereof will be omitted.

In the above-mentioned HST device, the free flowing oil is circulated in the free flowing oil circuit by the charge pump 22 even when the movable swash plate 6 of the variable displacement pump 2 is in the neutral state. Therefore, the hydraulic oil heater 35 is disposed in the pump-motor communication circuit 20 to lower the viscosity by increasing the oil temperature of the hydraulic oil at the time of starting in cold and cold weather. Thereby, the pump driving torque can be forcibly reduced.

FIG. 3 is a diagram showing the operation switch 61 of the general-purpose diesel engine.
FF is a stop position, ACC is a DC supply position for accessories, and start is an engine start position by a starter. In this configuration, when the operation switch 61 is operated to the preheating position, the current from the battery heats the glow plug, and when the operation switch 61 is operated to the start position, current flows to the starter and also to the glow plug.

After the operation switch 61 is operated to the preheating position or the start position, when the operation switch 61 is released, the built-in spring naturally returns to the OFF position. In such a configuration, in this embodiment, since the hydraulic oil heater 35 is connected in parallel with the glow plug 49 as shown in FIG. 2, the operation switch 61 is operated by operating the glow plug 49 to the preheating position. During this period (while the glow switch 48 is on), the hydraulic oil heater 35 is heated. Similarly, since the solenoid of the three-port electromagnetic solenoid valve 31 is also connected in parallel to the glow plug 49, the bypass line 30 is operated during the operation to the preheating position.
Will be switched to.

Further, since the glow switch 48 is on while the operation switch 61 is being operated to the start position in FIG. 3 (while the starter switch 46 is on), the glow switch 48 is also on during the starter start period. The hydraulic oil heater 34 is heated and the bypass line 30 is switched. Therefore, according to the HST device according to this embodiment, when the operator performs the preheating operation with the glow plug 49 in cold weather and when the starter 47 is started, the temperature of the hydraulic oil of the variable displacement pump is increased by the hydraulic oil heater 35. Therefore, the engine start limit temperature can be lowered.

While the glow switch 48 is turned on (preheating and starting), the oil return line 27 is switched to the bypass line 30 in the free-flowing oil supply circuit 19, so that the circulation is performed once. The operating oil whose temperature has increased can be used repeatedly, and the driving torque of the variable displacement pump can be reduced.

[0026]

Embodiment 2 FIG. 4 is a schematic control circuit diagram of a characteristic portion of an HST device according to a second embodiment of the present invention. This device applies a voltage from a battery 45 to a starter 47 via a starter switch 46, to a glow plug 49 via a glow switch 48, and to a hydraulic oil heater 35 via a normally open type heater switch unit 50. It is configured to apply. Note that, similarly to the first embodiment, when the starter switch 46 is short-circuited, the glow switch 48 is automatically short-circuited.

A first operation detecting section 51 (for example, a voltage or current detector) is interposed between the glow switch 48 and the glow plug 49, and a second operation detecting section 51 is provided between the starter switch 46 and the starter 47. A unit 52 (for example, a voltage or current detector) is interposed. The output of the second operation detection unit 52 is input to the heater switch unit 50 via the timer 53, and a predetermined time T from when the starter switch 46 is short-circuited by the operation of the timer 53.
The heater switch unit 50 is configured to maintain the short-circuit state by one.

The output of the second operation detecting section 52 is also input to the valve driving section 58, and only when the second operation detecting section 52 is detecting a voltage or a current, the three-port electromagnetic solenoid valve 31 controls the bypass line 30. The pipeline is switched to the next. Further, the first operation detecting section 51 short-circuits the heater switch section 50 for a time period during which the glow switch 48 is short-circuited. The heater switch unit 50 is configured to be in an open state (a state in which the hydraulic oil heater 35 is stopped) as soon as a command from the engine independent rotation detection unit 56 is input. The configuration of the operation switch 61 is the same as the configuration shown in the first embodiment.

FIG. 5 is a flowchart showing the operation of the hydraulic oil heater at the time of startup in cold or cold conditions in the present embodiment. The operation will be described with reference to FIGS. First, in step SP1, it is determined whether or not the operation switch 61 has been operated to the preheating position, that is, the glow switch 48.
Is determined to be in a short circuit state, and if it is determined that the preheating position has been operated, the hydraulic oil heater 35 is heated for the operation time in step SP2.

After the operating oil heater 35 has been heated for the time during which the preheating position has been operated, or when it is determined that the operation oil heater 35 has not been operated at the preheating position, the operation switch 61 is operated to the starting position in step SP3. It is determined whether or not the starter switch 46 has been short-circuited. If it is determined that the starter position has been operated, the hydraulic oil heater 35 is turned on for the set time T1 of the timer 53 in step SP4. Heating, step SP5
It is determined whether or not the engine has been started (whether the engine has been self-rotating). If it is determined that the engine has not been started, the heating of the hydraulic oil heater 35 in step SP4 is continued.

On the other hand, if it is determined in step SP5 that the engine has been started, even if the set time T1 has not elapsed, the heating of the hydraulic oil heater 35 is stopped in step SP6 and a series of processing is performed. finish. In the HST device according to this embodiment, the glow plug 4
Since the hydraulic oil heater 35 is driven while the motor 9 is driven, an effect of improving the engine startability can be obtained. Further, in this embodiment, the working machine and the engine are extremely low temperature, and even if the engine does not easily start up by only one preheating operation and starting operation, the start position and the preheating are controlled by the operation of the timer 53. The hydraulic oil heater 35 can be continuously heated even during the position switching time.

FIG. 6 is a flow chart for explaining the operation of the three-port solenoid valve in the second embodiment. First, in step SP1, the second operation detection unit 52 determines whether or not the starter 47 is being driven. If it is determined that the starter 47 is being driven, in step SP2, the valve driving unit 58 controls the three-port electromagnetic The solenoid valve 31 is switched so as to be connected to the bypass line 30. In step SP3, it is determined whether or not the starter 47 has been stopped. 31 to oil cooler 2
6. Switch to connect to the oil tank 21.

In this embodiment, the bypass line 30 is not switched when the operation switch is operated to the preheating position, but is switched to the bypass line 30 only when the starter 47 is driven. Also in this embodiment, since the operating oil which has been circulated once during the starter operation and the temperature of which has increased can be used repeatedly, the driving torque of the variable displacement pump can be reduced.

The present invention is not limited to the above embodiment, and various design changes can be made without departing from the scope of the present invention. Hereinafter, such an embodiment will be described. (1) In the above-described embodiment, the HST device having both the configuration in which the hydraulic oil heater is disposed in the free-flow oil circuit and the configuration in which the bypass pipe is disposed has been exemplified. Even so, the effect of improving the starting performance of the engine can be obtained. Further, it is preferable that the hydraulic oil heater is provided near the free-flow oil inlet port of the hydraulic pump in order to speed up the temperature rise of the oil, but the disposition position can be appropriately set according to each HST device. .

(2) In the above embodiment, the glow plug 49
Although the hydraulic oil heater 35 is driven in correspondence with the start of the glow plug 49 and the operation of the starter 47, a predetermined time, for example, 30 seconds from the start of the glow plug 49,
The hydraulic oil heater 35 may be forcibly heated, and may be unconditionally stopped after heating for 30 seconds. (3) In the above-described embodiment, a combination of a variable displacement pump and a constant displacement motor has been exemplified as the HST device. It is possible to arrange.

[Brief description of the drawings]

FIG. 1 is a schematic hydraulic circuit diagram for explaining an embodiment of an HST device according to the present invention.

FIG. 2 is a schematic control circuit diagram of a characteristic portion of the HST device according to the first embodiment of the present invention.

FIG. 3 is a diagram showing operation switches of a general-purpose diesel engine.

FIG. 4 is a schematic control circuit diagram of a characteristic portion of an HST device according to a second embodiment of the present invention.

FIG. 5 is a diagram showing an example of a flowchart for operating a hydraulic oil heater at the time of startup in cold or cold in the second embodiment.

FIG. 6 is a flowchart for explaining the operation of a three-port solenoid valve in the second embodiment.

[Explanation of symbols]

2 ... variable displacement pump, 3 ... HST closed circuit , 4 ... constant displacement
Type motor , 12 ... drive shaft, 18 ... output shaft , 19 ... free flowing oil supply circuit, 20 ... pump-motor communication circuit, 21 ... oil tank, 22 ... charge pump, 25 ... oil leak port, 24 ... oil supply pipe Channel, 26 oil cooler, 27 oil return line, 30 bypass line, 31 three-port solenoid valve, 33 oil inlet port, 34 oil leak port
G , 35: hydraulic oil heater, 49: glow plug.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16H 61/40-61/46

Claims (2)

(57) [Claims] 1. A drive shaft (12) directly connected to an engine.
Equipped with a hydraulic pump (2) and an output shaft (18)
The HST closed circuit (3) connects with the hydraulic pump (2).
Driven (4), including a hydraulic transmission
A hydraulic pump (2) and a motor.
Pump as a free-flowing oil line from the gap in the pump (4)
To leak into the data communication circuit (20).
The pump motor communication circuit (20) is connected to the hydraulic pump (2).
Free oil port (33) and motor (4) oil leak port
(34) and the pump
A hydraulic transmission device comprising: a hydraulic oil heater (35) provided in a motor communication circuit (20); and a hydraulic oil heater (35) driven in response to activation of an engine preheating device (49). 2. An engine drive shaft (12) of a work machine.
Free flow in the hydraulic transmission system
Free flow of hydraulic pump (2) in oil circuits (19) and (20)
A hydraulic oil heater (35) is installed near the oil inlet port (33).
While starting the engine preheating device (49).
In response, the hydraulic oil heater (35) is driven to freely recover the free flowing oil from the free flowing oil outlet port (25) of the hydraulic pump (2) to the oil tank (21) via the heat exchanger (26). Flow oil return line (27) and oil tank (2
A free-flowing oil supply line (24) that supplies the oil from 1) again to the hydraulic pump (2) by the charge pump (22)
And a free-flow oil return pipe (27) and a free-flow oil supply pipe (2) without passing through a heat exchanger (26) and an oil tank (21).
4), and a 3-port switching valve (31) provided at a communication portion between the bypass pipe (30) and the free-flowing oil supply pipe (24). A hydraulic transmission device characterized in that the flow of free flowing oil is switched to a bypass line (30) during a period.