KR20180137886A - The oil hydraulic system for a forklift truck - Google Patents

Abstract

The present invention relates to a hydraulic system for a forklift truck. According to the present invention, the hydraulic system for a forklift truck comprises an oil return processing unit on an oil discharge path of a second pump, wherein the oil return processing unit selectively returns oil discharged from the second pump to an oil tank when a gear is placed in a forward or backward mode, and a working apparatus is a tilt-in or a lift state during a low idle condition of an engine. Accordingly, even if a driver of the forklift truck advances an operation to tilt-in or lift the working apparatus while placing the gear of the forklift truck in the low idle condition of the engine, a second pump side is prevented from discharging the oil stored in the oil tank to a control valve at high pressure (In other words, the oil discharged from the second pump is guided to return to the oil tank). Therethrough, a load to be loaded on an engine side is minimized and thus a driver side of the forklift truck is able to avoid an inconvenient situation, such as sudden stop of the forklift truck during operation and the like.

Description

[0001] The present invention relates to a hydraulic system for a forklift truck,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a hydraulic system installed in a forklift, and more particularly, to a hydraulic system installed in a forklift. More specifically, the gear is placed in a forward mode or a reverse mode under low- An oil return processing unit capable of selectively returning the oil discharged by the second pump to the oil tank when the working device is tilted-in or lifted, Even if the forklift driver moves the gear of the forklift in the forward mode or the reverse mode under the low idle condition of the engine and tilts-in or lifts the working device, (I.e., the oil discharged by the second pump can be returned to the oil bank) at the second pump side, Via, by giving in to lower the load on the engine side, which can take a minimum, the forklift driver's side, the present invention relates to a hydraulic system for a forklift truck with a forklift during the start-up operation can be guided to avoid getting in uncomfortable situations such as sudden off.

Recently, as the technology related to the forklift has been rapidly developed, the hydraulic system installed in the forklift is also undergoing extensive development.

For example, Korean Patent Registration No. 10-1023744 entitled "Hydraulic System of Forklift Truck" (issued on March 25, 2011), Korean Patent Laid-Open No. 10-2013-128850 (entitled "Hydraulic System of Forklift Truck"). 27-19, No. 3, June, 2003), Korean Patent No. 10-1343831 (titled "Hydraulic System of Forklift Truck") (published on Dec. 20, 2013) and the like disclose an example of a hydraulic system for a forklift according to this conventional technique in more detail have.

1, a hydraulic system 1 for a forklift according to the related art includes an electronic control unit (ECU) 10, a first pump 4 and a second pump 5 An engine 2 serving as a power source for the first pump 4 and the second pump 5 of the pump module 3 while being controlled by the ECU 10, (Oil) (for example, hydraulic oil) discharged by the first pump 4 and the second pump 5 under the control of the ECU 10 via the oil circulation line 14 9) and a control valve 7 for driving the working device 9 (for example, a tilt cylinder, a lift cylinder, an attachment, etc.) are tightly combined.

In this case, on the ECU 10 side, for example, a function of detecting / controlling an unnecessary pressure increase phenomenon during operation of the working device 9 while taking a structure electrically connected to the hydraulic pressure sensor 8, A function of operating the engine 2 in accordance with the driving state of the accelerator 11 and the gear 16 while taking a structure electrically connected to the accelerator 11, the engine 2, the gear 16, And controls the ON / OFF state of the control valve 7 while taking a structure electrically connected to the control valve 7, and so on.

The first pump 4 and the second pump 5 are driven in accordance with the operating states of the engine 2 and the gear 6 so that the oil stored in the oil tank 6 To the control valve 7 through the oil circulation lines 12 and 13 at a high pressure.

Under such a conventional system, on the forklift driver side, the work device 9 is moved in the forward or reverse mode while the gear 16 of the forklift is placed under the low idle condition of the engine 2 Tilt-in or lift operation ".

However, as described above, while the forklift driver places the gear 16 of the forklift in the forward mode or the reverse mode under the low idle condition of the engine 2, (For example, hydraulic oil) stored in the oil tank 6 on the side of the second pump 5 as well as the first pump 4, Pressure discharge to the engine 2 side by the control valve 7 through the oil circulation lines 12 and 13 so as to take an excessive load corresponding to the second pump 5 as well as the first pump 4. [ Inevitably, the forklift driver will have to face the uncomfortable situation such as suddenly turning off the forklift during operation.

Of course, if the start of the forklift suddenly turns off during the operation, the driver of the forklift will be forced to suffer damage which greatly decreases the overall operation efficiency.

Korean Registered Patent No. 10-1023744 (Name: Hydraulic System of Forklift Truck) Korean Patent Laid-Open No. 10-2013-128850 (Name: Hydraulic System of Forklift Truck) (Released on November 27, 2013) Korean Registered Patent No. 10-1343831 (Name: Hydraulic System of Forklift Truck) (Official Notice)

Accordingly, an object of the present invention is to provide a hydraulic pump which is capable of operating on the oil discharge path of a second pump in which the gear is placed in a forward mode or a backward mode under a low idle condition of the engine and a working device is tilt- And an oil return processing unit capable of selectively returning the oil discharged by the second pump to the oil tank when the lift truck is lifted or lifted, (Tilt-in) or a lift operation of the working device while the gear of the forklift is placed in the forward mode or the reverse mode under the condition (I.e., the oil discharged by the second pump can be returned to the oil bank) through the control valve so that the load on the engine side can be minimized So as to guide the driver of the forklift truck against inconvenience such as suddenly turning off the forklift during operation.

Other objects of the present invention will become more apparent from the following detailed description and the accompanying drawings.

In order to achieve the above object, the present invention provides an electronic control unit (ECU) A gear and an engine controlled by the ECU; A first pump and a second pump driven in accordance with the operation state of the gear and the engine to discharge the oil stored in the oil tank; A control valve for supplying the oil discharged by the first pump and the second pump to the working device while being controlled by the ECU to drive the working device; Wherein the gear is disposed in a forward mode or a reverse mode under a low idle condition of the engine and the working device is a tilt-in or tilting mode, And an oil return processing unit for returning the oil discharged by the second pump to the oil tank when it is lifted.

In the present invention, the gear is placed in the forward mode or the reverse mode under the low idle condition of the engine, and the working device is tilted in the tilt-in or the lift And the oil returning unit capable of selectively returning the oil discharged by the second pump to the oil tank when the lift is performed by the second pump, Even if the work of tilting-in or lifting the working device is advanced while the gear of the forklift is placed in the forward mode or the backward mode, the oil stored in the oil tank at the second pump side (That is, the oil discharged by the second pump can be returned to the oil bank) can be prevented from being discharged to the forklift driver side It is possible to enjoy the effect of minimizing the load applied to the engine, and as a result, it is not inconvenient that the start of the forklift suddenly turns off during the operation.

1 is an exemplary view conceptually showing a hydraulic system for a forklift according to a conventional technique;
BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a hydraulic system for a forklift.
3 is an exemplary view conceptually showing a detailed configuration of an oil return processing unit according to one embodiment of the present invention.
4 is an exemplary view conceptually showing a detailed configuration of an oil return processing unit according to another embodiment of the present invention;

Hereinafter, a hydraulic system for a forklift according to the present invention will be described in detail with reference to the accompanying drawings.

2, the hydraulic system 100 for a forklift according to the present invention includes an electronic control unit (ECU) 110, a first pump 104 and a second pump 105 An engine 102 serving as a power source for the first pump 104 and the second pump 105 of the pump module 103 while being controlled by the ECU 110, (Oil) (for example, hydraulic oil) discharged by the first pump 104 and the second pump 105 to the working device 109 via the oil circulation line 114 And a control valve 107 for driving the working device 109 (for example, a tilt cylinder, a lift cylinder, an attachment, etc.) and the like are tightly combined.

In this case, on the ECU 110 side, for example, it takes a structure that is electrically connected to the hydraulic pressure sensor 108 and detects / controls an unnecessary pressure increase phenomenon during operation of the working device 109, A function of operating the engine 102 in accordance with the driving state of the accelerator 111 and the gear 116 while taking a structure electrically connected to the accelerator 111, the engine 102, the gear 116, And controls the on / off state of the control valve 107 while taking a structure electrically connected to the control valve 107.

The first pump 104 and the second pump 105 are driven in accordance with the operation states of the engine 102 and the gear 116 to thereby store the oil stored in the oil tank 106 ) To the control valve 107 through the oil circulation lines 112 and 113 at a high pressure.

Under the low idle condition of the engine 102, while the gear 116 of the forklift is positioned in the forward mode or the reverse mode depending on the situation, (Tilt-in) or lift (lift) operation of the tilting mechanism 109>.

Of course, even under this situation, the oil stored in the oil tank 106 (for example, oil of hydraulic fluid, for example, oil) stored on the second pump 105 side as well as the first pump 104 Pressure discharge to the control valve 107 through the oil circulation lines 112 and 113 so that an excessive load corresponding to the second pump 105 as well as the first pump 104 is applied to the engine 102 side As a result, the forklift driver is forced to face the uncomfortable situation such as suddenly turning off the forklift during operation.

2, in the present invention, on the oil circulation line 115 which is the oil discharge path of the second pump 105, under the low idle condition of the engine 102 When the gear 116 is placed in the forward mode or the reverse mode and the working device 109 is tilt-in or lifted, the oil discharged by the second pump 105 is returned to the oil The oil return processing unit 120, which can be selectively returned to the oil tank 106 via the distribution line 117, is additionally disposed.

3, the oil return processing unit 120 according to one embodiment of the present invention communicates with the ECU 110 while under the low idle condition of the engine 102, When the working device 109 is placed in the forward or backward mode and the working device 109 is tilt-in or lifted, the flow direction switching And is connected to the flow direction switching indication valve 121 in a state in which it is disposed on the indication valve 121 and on the oil circulation line 115 which is the oil discharge path of the second pump 105, The direction of the oil discharged by the second pump 105 is switched to the oil circulation line 114 side and the oil is returned to the oil tank 106 when the oil circulation path 121 is turned on, And the valves 122 are structurally combined.

In the system of the present invention, when the forklift driver takes an action such as the normal operation and operates the accelerator 111, the flow direction changeover instruction valve 121 is turned off, State.

Of course, when the flow direction switching indication valve 121 is maintained in the turn-off state, the flow direction switching valve 122 also does not perform any other oil direction switching operation, and as a result, the second pump 105 (See FIG. 3) through the oil circulation lines 115 and 113 and to the control valve 107 at high pressure.

However, when the forklift driver moves the work device 109 to the tilt-in state (i.e., while the gear 116 of the forklift is in the forward mode or the reverse mode) under the low idle condition of the engine 102 Tilt-in or lift>, the flow direction changeover switch valve 121 communicates with the ECU 110 to change the state of the engine 102 idle condition, the gear 116 is placed in the forward or reverse mode, and the working device 109 is tilted-in or lifted), immediately thereafter, State to a turn-on state.

Of course, in accordance with the above procedure, when the flow direction changeover indicating valve 121 is changed to the turn-on state, the flow direction changeover valve 122 side is immediately activated, The direction of the oil is switched to the oil circulation line 114 side, and the process of returning the oil to the oil tank 106 is performed.

Naturally, according to the above procedure, when the direction of the oil discharged by the second pump 105 is switched to the oil circulation line 114 side and the oil is returned to the oil tank 106, The gear 116 of the forklift can be placed in the forward mode or the low load mode in the forklift driver side under the low idle condition of the engine 102. In other words, The tilt-in or lift operation of the working device 109 while moving the work machine 109 in the backward mode is carried out and the start of the forklift is suddenly shut down during the work, Without much difficulty, it is possible to enjoy the benefits of improved overall operating efficiency.

As described above, in the present invention, the gear 116 is placed in the forward mode or the reverse mode under the low idle condition of the engine 102 on the oil discharge path of the second pump 105, The oil return processing unit 120 which can selectively return the oil discharged by the second pump 105 to the oil tank 106 when the oil tank 109 is tilt-in or lifted, And the operation device 109 is moved to the tilting state while the forklift driver places the gear 116 of the forklift in the forward mode or the reverse mode under the low idle condition of the engine 102 The oil stored in the oil tank 106 can be prevented from being discharged at a high pressure by the control valve 107 at the side of the second pump 105 even if the operation of advancing the tilt- (I.e., the oil discharged by the second pump can be returned to the oil bank) It is possible to enjoy the effect of minimizing the load on the engine 102 on the side of the forklift driver under the implementation environment of the present invention and eventually to the inconvenience of suddenly turning off the start of the forklift during the operation .

4, in another embodiment of the present invention, the oil return processing unit 120 includes a flow direction changeover valve 121, a flow direction changeover valve 122, 123, < / RTI >

At this time, on the side of the pressure condition control valve 123, the structure is arranged on the oil circulation line 115 which is the oil discharge path of the second pump 105, the structure which is electrically connected to the flow direction switching valve 122, Only when the pressure of the oil discharged from the second pump 105 is equal to a preset value while the pump 105 is operating.

At this time, the flow direction switching valve 122 is operated only when both the flow direction switching indication valve 121 and the pressure condition control valve 123 are in the turn-on state, and is supplied to the second pump 105 The direction of the oil discharged by the oil tank 106 is switched to the oil tank 106 side.

Of course, when the pressure condition control valve 123 is selectively operated to turn on only when the pressure of the oil discharged from the second pump 105 corresponds to a predetermined value, , The flow direction switching valve 122 also switches the direction of the oil discharged by the second pump 105 to the oil tank 106 side only when the pressure of the oil corresponds to a predetermined value, The advantage of being able to operate the oil return processing unit 120 of the present invention only under a desired load condition (or an oil pressure condition) can be widely enjoyed on the forklift driver side, for example.

In the other embodiment of the present invention, when the forklift driver performs an ordinary operation to take action such as operating the accelerator 111, the flow direction changeover instruction valve 121, the pressure condition control valve 121, Off state on the side of the controller 123 in FIG.

Of course, when the flow direction switching indication valve 121, the pressure condition control valve 123, and the like are maintained in the turn-off state, the flow direction switching valve 122 does not perform any other oil direction switching operation As a result, the oil discharged by the second pump 105 undergoes a high-pressure discharge process through the oil flow lines 115 and 113 to the control valve 107 (see FIG. 4).

However, when the forklift driver moves the work device 109 to the tilt-in state (i.e., while the gear 116 of the forklift is in the forward mode or the reverse mode) under the low idle condition of the engine 102 Tilt-in or lift>, the flow direction changeover switch valve 121 communicates with the ECU 110 to change the state of the engine 102 idle condition, the gear 116 is placed in the forward or reverse mode, and the working device 109 is tilted-in or lifted), immediately thereafter, State to a turn-on state.

In addition, the forklift driver can operate the tilting-in apparatus (not shown) by placing the gear 116 of the forklift in the forward mode or the reverse mode under the low idle condition of the engine 102 When the pressure of the oil discharged from the second pump 105 is equal to a preset value under an environment in which the operation of pushing the tilt-in or the lift of the pressure control valve 123 proceeds, State to a turn-on state.

Of course, when the flow direction switching indication valve 121, the pressure condition control valve 123, etc. are changed to the turn-on state according to the above procedure, the flow direction switching valve 122 immediately starts operating, 2 pump 105 to the side of the oil circulation line 114 so that the oil is returned to the oil tank 106 through the circulation of the oil.

Naturally, according to the above procedure, when the direction of the oil discharged by the second pump 105 is switched to the oil circulation line 114 side and the oil is returned to the oil tank 106, The gear 116 of the forklift can be placed in the forward mode or the low load mode in the forklift driver side under the low idle condition of the engine 102. In other words, The tilt-in or lift operation of the working device 109 while moving the work machine 109 in the backward mode is carried out and the start of the forklift is suddenly shut down during the work, Without much difficulty, it is possible to enjoy the benefits of improved overall operating efficiency.

As described above, in the other embodiment of the present invention as described above, the gear 116 is moved in the forward mode or the reverse direction (the reverse direction) under the low idle condition of the engine 102 on the oil discharge path of the second pump 105 Mode and is capable of selectively returning the oil discharged by the second pump 105 to the oil tank 106 when the working device 109 is tilt-in or lifted The oil return processing unit 120 is arranged so that the forklift driver places the gear 116 of the forklift in the forward mode or the reverse mode under the low idle condition of the engine 102, The oil stored in the oil tank 106 is supplied to the control valve 107 (or the oil tank 106) from the second pump 105 side even if the operation of tilting-in or lifting the working device 109 is advanced. (That is, the oil discharged by the second pump is not supplied to the oil bank < RTI ID = 0.0 > It is possible to enjoy the effect of minimizing the load applied to the engine 102 on the side of the forklift driver even under the different implementation environment of the present invention and eventually the start of the forklift suddenly It is not subjected to an uncomfortable situation such as turning off.

The present invention provides a generally useful effect in various fields where it is necessary to prevent unnecessary start-off phenomenon.

Although specific embodiments of the present invention have been described and illustrated above, it is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.

Such modified embodiments should not be understood individually from the technical idea and viewpoint of the present invention, and such modified embodiments should be included in the appended claims of the present invention.

1,100: Hydraulic system for forklifts
2,102: engine
3,103: Pump module
4,104: First pump
5,105: Second pump
6,106: Oil tank
7,107: Control valve
8,108: Hydraulic sensor
9,109: Working device
10,110: ECU
11,111: Accelerator
12,13,14,112,113,114,115,117: Oil distribution line
16,116: Gear
120: Oil return processing unit
121: Flow direction switching indicator valve
122: Flow direction switching valve
123: Pressure condition control valve

Claims (4)

An electronic control unit (ECU);
A gear and an engine controlled by the ECU;
A first pump and a second pump driven in accordance with the operation state of the gear and the engine to discharge the oil stored in the oil tank;
A control valve for supplying the oil discharged by the first pump and the second pump to the working device while being controlled by the ECU to drive the working device;
Wherein the gear is disposed in a forward mode or a reverse mode under a low idle condition of the engine and the working device is a tilt-in or tilting mode, And an oil returning unit for returning the oil discharged by the second pump to the oil tank when the oil tank is lifted. The apparatus according to claim 1, wherein the oil return processing unit communicates with the ECU, wherein, under low idle condition of the engine, the gear is located in a forward mode or a reverse mode, A flow direction changeover indicating valve in a turn-on state when it is tilt-in or lift;
Wherein the flow direction switching valve is electrically connected to the flow direction switching indicating valve in a state in which it is disposed on the oil discharge path of the second pump and when the flow direction switching indicating valve is in a turn- And a flow direction switching valve for switching the direction of the oil and returning the oil to the oil tank. 3. The oil pump according to claim 2, wherein the oil return processing unit is electrically connected to the flow direction switching valve in a state of being disposed on the oil discharge path of the second pump, and the pressure of the oil discharged from the second pump Only when the flow rate directional control valve is in the turned-on state only when it corresponds to the set value, the direction of the oil discharged by the second pump is changed to the oil Further comprising a pressure condition control valve for allowing the hydraulic pressure to be switched to the tank side. 4. The hydraulic control apparatus according to claim 3, wherein the flow direction switching valve is configured to switch the direction of the oil discharged by the second pump to the oil tank side only when both the flow direction switching indication valve and the pressure condition control valve are in the turn- Wherein the hydraulic system is a hydraulic system for a forklift.

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