WO2011021859A2

WO2011021859A2 - Steering device for construction machinery

Info

Publication number: WO2011021859A2
Application number: PCT/KR2010/005481
Authority: WO
Inventors: 장인표
Original assignee: 두산인프라코어 주식회사
Priority date: 2009-08-19
Filing date: 2010-08-19
Publication date: 2011-02-24
Also published as: WO2011021859A3

Abstract

The present invention relates to construction machinery such as wheel loaders, which comprises a steering actuator, a hydraulic pump able to discharge operating oil in two directions under drive by means of a swash plate, a pair of drive oil ducts constituting a closed loop connecting the steering actuator and the hydraulic pump, and a pump control unit which receives input in the form of signals in response to manipulation of a steering means by a driver; wherein the pump control unit comprises a swash-plate driving cylinder which is connected at one end to the swash plate (21) and is driven and varies the angle of inclination of the swash plate when operating oil is supplied and thereby varies the volume of discharge and the direction of discharge of the hydraulic pump, and a swash-plate control valve which receives input in the form of signals in response to manipulation of the steering means by the driver and is thereby turned around and so controls the amount and the direction of the operating oil supplied to the swash-plate driving cylinder.

Description

Steering Device of Construction Machinery

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a construction machine such as a wheel loader, and more particularly, to a steering apparatus of a construction machine that can reduce a driver's fatigue and improve steering controllability in consideration of a user's convenience.

In general, a construction machine such as a wheel loader changes the driving direction by supplying hydraulic oil discharged from a pump to a steering actuator. More specifically, when the operator operates the steering wheel, the hydraulic oil is discharged at a flow rate proportional to the operation amount of the steering wheel by the steering unit connected to the steering handle. The discharged hydraulic oil switches the steering valve in a direction proportional to the operation direction and the operation amount of the steering wheel. The switched steering valves are supplied from the main pump of the machine to allow atmospheric hydraulic fluid to be supplied to the steering actuators. In this way, the steering actuator is driven in response to the manipulation amount and the manipulation direction of the steering handle, thereby making steering of the equipment.

In the conventional steering apparatus, since the hydraulic oil supplied from the main pump is supplied through various valves including the steering valve of the main control valve, the pressure loss of the hydraulic oil is large. In addition, since the hydraulic oil supplied from the main pump must be shared with other driving products such as the main control valve / brake / cooling fan, there is a problem in that the steering response is poor and the driver's satisfaction is low.

In addition, in recent years, there is also a request to enable the steering of the equipment by using the electronic steering lever, but in the case of using a complicated mechanical device as in the prior art, when the above-described additional functions are added, the structure becomes more complicated and the safety is low. There are also problems that are difficult to satisfy.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object thereof is to provide a steering apparatus for construction machinery that can simplify the structure to reduce costs and prevent fuel deterioration caused by pressure loss of hydraulic oil.

Steering device for a construction machine according to the present invention for achieving the above object is a steering actuator (10); A hydraulic pump 20 capable of discharging hydraulic oil in both directions by driving of a swash plate; A pair of

drive flow paths

31 and 32 connecting the steering actuator 10 and the hydraulic pump 20 to form a closed circuit; And a pump control unit (60, 160) for controlling the swash plate (21) of the hydraulic pump (20) by receiving a signal corresponding to the driver's steering means (45) operation, wherein the pump control unit (60, 160) A swash plate driving cylinder 61 which is connected to one side of the swash plate 21 and is driven when the operating oil is supplied to change the discharge amount and the discharge direction of the hydraulic pump by changing the inclination angle of the swash plate; And a swash plate control valve 62 which receives a signal corresponding to an operation of the steering means 45 of the driver and is switched to control a supply amount and a supply direction of the hydraulic oil supplied to the swash plate drive cylinder 61.

According to one embodiment of the present invention, by charging the hydraulic fluid in the replenishment line 39 connected to the pair of drive passages (31,32), charging to refill the hydraulic oil of the pair of drive passages (31,32) The pump 50 is further included, The charging pump 50 is further connected to the swash plate control valve 62 through a second supply line 52, the swash plate via the swash plate control valve 62 Hydraulic fluid can also be supplied to the drive cylinder 61.

In addition, the steering device has one side connected to the operation means 45, the other side through the first and second steering signal line (41, 42) hydraulic pressure section (62a, 62b) of the swash plate control valve 62 And a steering unit 40 connected to the hydraulic oil to be able to switch the swash plate control valve 62 in response to an operation of the steering means 45 of the driver. 2 steering signal lines (41, 42) to gradually vary the pressure of the hydraulic oil applied to the hydraulic pressure section (62a, 62b) of the swash plate control valve 62 in proportion to the flow rate discharged from the steering unit (40) The pressure conversion unit 63 is installed.

The pressure conversion unit 63 is installed to connect the tank with the first and second

steering signal lines

41 and 42, and is drained to the tank in proportion to the flow rate of the hydraulic oil discharged from the steering unit 40. And a pressure conversion valve 63c for adjusting the flow rate to vary the pressure in the first and second

steering signal lines

41 and 42.

The steering unit 40 further includes a first supply line 51 connecting the charging pump 50 and the steering unit 40 to control the hydraulic oil supplied from the charging pump 50 to control the swash plate. Supply to the control valve 62.

According to another embodiment of the invention, the sensor (45a) for outputting the operation information corresponding to the operation amount and the operation direction of the steering means 45; And a controller (VCU, 100) outputting a control signal in response to the operation information of the steering means (45) input from the sensor (45a), wherein the swash plate control valve (162) is the controller (100). It is an electronic control valve whose drive is controlled by a control signal output from

First, the steering apparatus of the construction machine according to the present invention can simplify the configuration of the steering circuit by connecting the hydraulic pump and the steering actuator to the closed circuit by the first and second drive passages. In addition, the simplification of the structure can reduce the pressure loss by each component, thereby improving the energy efficiency.

Secondly, the steering apparatus of the construction machine includes a swash plate driving cylinder, a swash plate control valve, and a pressure converting unit, so that the flow rate of the hydraulic oil discharged from the hydraulic pump increases even if the steering unit is suddenly operated and excessive flow rate occurs. Can be prevented, whereby the energy efficiency can be further improved.

Third, the steering apparatus of the construction machine includes a pressure conversion valve in which the pressure conversion unit gradually varies the pressure of the steering signal line according to the discharge flow rate of the steering unit, thereby further simplifying the steering circuit. Moreover, by using the relief valve as a pressure conversion valve and by varying the pressure of the steering signal line by using the override characteristic of the relief valve, not only can the steering circuit be further simplified, but also the energy efficiency can be minimized by minimizing pressure loss by hydraulic components. It can be maximized.

Fourthly, the steering apparatus of the construction machine applies a variable pump using a closed circuit, and considers both the operation information of the steering means (steering handle or steering lever), the engine speed, the traveling speed information, and the operation information of the actuator. Since the discharge is controlled electronically, the steering performance and the steering controllability are greatly improved, thereby enabling optimal steering control.

1 is a hydraulic circuit diagram schematically showing a steering apparatus of a construction machine according to Embodiment 1 of the present invention;

2 is a hydraulic circuit diagram schematically showing a steering device for a construction machine according to Embodiment 2 of the present invention;

3 is a graph schematically showing a proportional current value that is changed when the rotation angle of the steering wheel is increased or the flow of the steering lever is increased according to the mode selection;

4 is a graph schematically showing a proportional current value for controlling the pump that changes when the volume of the steering pump is increased according to the mode selection.

Hereinafter, with reference to the drawings will be described in detail for the steering apparatus of the construction machine according to each embodiment of the present invention.

Example 1

Referring to FIG. 1, a steering apparatus of a construction machine according to Embodiment 1 of the present invention may include a steering actuator 10, a hydraulic pump 20, and first and second

driving flow paths

31 and 32. A closed circuit 30 connecting the hydraulic pump 20 and the steering actuator 10 and a pump control unit controlling the direction and flow rate of the hydraulic oil supplied from the hydraulic pump 20 to the steering actuator 10 ( 60, a steering unit 40 for discharging hydraulic fluid having a variable discharge flow rate and direction corresponding to the driver's steering means 45 to the pump control unit 60, the closed circuit 30, and the steering unit ( And a charging pump 50 for supplying hydraulic oil to 40).

The steering actuator 10 is for steering by driving a steering wheel. In Example 1, a steering cylinder is illustrated. The steering actuator 10 is stretched and driven according to the direction in which the hydraulic oil is supplied, and the steering wheel is steered by the stretching drive.

The hydraulic pump 20 is connected to a driving source such as an engine or an electric motor, not shown, and the discharge flow rate and discharge direction of the hydraulic oil are varied according to the inclination angle of the swash plate 21. That is, when the swash plate 21 is inclined in the '+' direction, the hydraulic pump 20 discharges the hydraulic oil to the first driving channel 31 and sucks the hydraulic oil through the second driving channel 32, and the swash plate 21. When () is inclined to '-' it is possible to supply a two-way hydraulic fluid to discharge the hydraulic oil to the second drive flow path 32 and suck the hydraulic oil from the first drive flow path (31). Thereby, the hydraulic circuit which supplies hydraulic oil to the steering actuator 10 can be comprised by a closed circuit. Here, the discharge flow rate varies depending on the inclination angle of the swash plate 21.

The closed circuit 30 connects the hydraulic pump 20 and the steering actuator 10 to the first and

second driving passages

31 and 32. Therefore, the hydraulic oil discharged from the hydraulic pump 20 is supplied to the steering actuator 10 through one of the first and second

driving flow paths

31 and 32, and from the steering actuator 10. The discharged working oil flows into the hydraulic pump 20 through one of the other flow paths of the first and second

driving flow paths

31 and 32.

The pump control unit 60 is for controlling the discharge flow rate and the discharge direction of the hydraulic pump 20 in response to the operation of the steering means 45, the swash plate drive cylinder 61 and the swash plate control valve 62 ) And a pressure conversion unit 63.

The swash plate driving cylinder 61 is connected to one side of the swash plate 21 of the hydraulic pump 20 to incline and drive the swash plate 21 in one direction or the other direction. The swash plate drive cylinder 61 is driven by operating oil supplied from the outside and whose supply direction is changed by the swash plate control valve 62. To this end, the swash plate driving cylinder 61 has

chambers

61a and 61b to which hydraulic oil is supplied, and the swash plate 21 is inclined according to whether or not the hydraulic oil is supplied to each of the

chambers

61a and 61b. The driving direction and the inclination driving amount are determined. The inclined drive amount of the swash plate 21 determines the discharge flow rate of the hydraulic pump 20, and the inclined drive direction of the swash plate 21 determines the discharge direction of the hydraulic pump 20.

The swash plate control valve 62 has first and second hydraulic pressure parts 62a and 62b to which the first and second

steering signal lines

41 and 42 respectively to be described later are connected, and the swash plate driving cylinder 61 is provided. ) Is installed on the hydraulic line for supplying the working oil. In this embodiment, the hydraulic oil for driving the swash plate driving cylinder 61 is supplied by the charging pump 50 to be described later. 1 illustrates a case in which the swash plate control valve 62 is neutral. In this state, the swash plate control cylinder is drained by draining the hydraulic oil supplied from the charging pump 50 through the second supply line 52 to the tank T. Allow 61 to remain neutral.

On the other hand, when a high pressure signal pressure is applied to the first pressure receiving part 62a and a low pressure signal pressure is applied to the second pressure receiving part 62b, the swash plate control valve 62 is converted to one side to provide the charging pump. The hydraulic oil of 50 is supplied to the first chamber 61a of the swash plate drive cylinder 61 and the hydraulic oil of the second chamber 61b of the swash plate drive cylinder 61 is drained. As a result, the swash plate driving cylinder 61 inclines and drives the swash plate 21 of the hydraulic pump 20 in one direction.

On the contrary, when a low pressure signal pressure is applied to the first pressure receiving part 62a and a high pressure signal pressure is applied to the second pressure receiving part 62b, the swash plate control valve 62 is converted to the other side to provide the charging pump. The hydraulic fluid of 50 is supplied to the 2nd chamber 61b of the said swash plate drive cylinder 61, and the hydraulic oil of the 1st chamber 61a of the swash plate drive cylinder 61 is drained. As a result, the swash plate drive cylinder 61 is inclined to the other direction of the swash plate 21 of the hydraulic pump 20.

The steering unit 40 is for switching the swash plate control valve 62 according to the operation amount and the operation direction of the steering means 45. That is, the steering unit 40, when the steering means 45 is operated, by adjusting the discharge direction of the hydraulic fluid corresponding to the operation direction, the hydraulic oil to either side of the first and second

steering signal lines

41, 42 Is discharged to supply hydraulic oil to any one of the first and second

hydraulic pressure portions

61a and 61b of the swash plate control valve 62. The hydraulic oil to be supplied to the first and second

steering signal lines

41 and 42 may be supplied by an external separate pump. In the present embodiment is supplied via the first supply line 51 from the charging pump 50 to be described later.

The pressure conversion unit 63 is for adjusting the oil pressure of the hydraulic oil discharged from the steering unit 40 and supplied to the hydraulic pressure parts 62a and 62b of the swash plate control valve 62. In the present invention, since the swash plate control valve 62 is driven when the driver operates the steering means 45, the first and second

steering signal lines

41 and 42 when the steering means 45 is suddenly operated even at a small amount. Increasing the pressure of) may cause the steering angle to be formed larger than the steering angle desired by the driver. That is, it is for preventing the swash plate control valve 62 from being completely opened in either direction regardless of the driver's operation amount. Accordingly, in this embodiment, the pressure converting unit 63 is used to control the pressures of the first and second

steering signal lines

41 and 42. To this end, the pressure conversion unit 63 is provided with a drawing line 63a which is drawn out from the first and second steering signal lines 42 and the drawing line 63a and is provided with the first and second steering signal lines ( 41 and 42, a pair of check valves 63b for preventing back flow of the hydraulic oil, and a pressure conversion valve connected to the withdrawal line 63a to selectively drain the hydraulic oil of the withdrawal line 63a. (63c). In this configuration, when the pressure of the first and second

steering signal lines

41 and 42 increases rapidly, the swash plate drive cylinder 61 is driven by the driver's desired steering angle by not passing it to the swash plate control valve 62. Can be controlled.

When the pressure of the first and second

steering signal lines

41 and 42 is less than or equal to 6 bar, the system atmospheric pressure, the pressure conversion valve 63c is maintained in an initial state as shown in FIG. . Therefore, the hydraulic oil of the lead-out line 63a is not drained. On the other hand, when the flow rate discharged from the steering unit 40 increases by operating the steering means 45, the pressure of the lead-out line 63a starts to rise and the pressure conversion valve 63c starts to open, and withdraws. The hydraulic oil of the line 63a starts to drain. Since this opening is very small, a very small amount is drained than the flow rate supplied to the hydraulic parts 62a and 62b of the swash plate control valve 62. However, the following effects can be expected by the flow rate drained. That is, when the discharge flow rate of the steering unit 40 gradually increases, the opening amount of the pressure conversion valve 63c gradually increases while the pressure of the lead-out line 63a gradually rises. This is a characteristic of the override pressure of the pressure conversion valve 63c itself, and a pressure difference occurs between the cracking pressure at the initial opening time of the pressure conversion valve 63c and the full flow pressure. do. This pressure difference is called the 'override pressure'. In Example 1, the pressure at the initial opening time is set to 6 bar and the pressure at the full flow opening is set to 18 bar, but the pressure may be changed according to the steering system.

FIG. 3 is a graph showing the inclination driving amount of the swash plate angle of the hydraulic pump 20 according to the pressure applied to the hydraulic pressure parts 62a and 62b of the swash plate control valve 62, and the horizontal axis of FIG. 3 is a swash plate control valve. It is the pressure applied to the hydraulic parts 62a and 62b of 62, and a horizontal axis is the inclination drive ratio (ratio with respect to the maximum swash plate angle) of the swash plate 21 of the hydraulic pump 20. As shown in FIG. As shown in FIG. 3, when the signal pressure applied to the hydraulic pressure parts 62a and 62b is 6 bar or less, the swash plate 21 of the hydraulic pump 20 is in the initial position, and the hydraulic pressure part 62a ( When the pressure applied to 62b) exceeds 6 bar, it is inclinedly driven to one side ('+' inclined direction) or the other side ('-' inclined direction). When the signal pressure of the pressure receiving parts 62a and 62b is 18 bar, the inclination angle of the swash plate 21 becomes maximum. Here, as mentioned above, the pressure applied to the hydraulic pressure parts 62a and 62b of the swash plate control valve 62 is the same as the pressure of the lead line 63a of the pressure conversion valve 63c. Therefore, the inclination drive of the swash plate 21 of the hydraulic pump 20 can be precisely controlled by adjusting the swash plate control valve 62 and the pressure conversion valve 63c.

Thus, by utilizing the overwrite characteristic of the pressure conversion valve 63c, the pressure of the first and second steering signal lines 41 and 42 (same as the pressure of the lead-out line 63a) is controlled by the steering unit 40. The pressure is increased in proportion to the discharge flow rate of the swash plate, and this pressure is applied to the pressure receiving parts 62a and 62b of the swash plate control valve 62. In this way, by utilizing the override characteristic of the pressure conversion valve 63c, not only can a structure be simplified but also a plurality of valves for converting the discharge flow rate of the steering unit into the signal pressure. The generated pressure loss can be minimized to improve the energy consumption efficiency.

Although the configuration in which the pressure conversion valve 63c is driven by hydraulic pressure has been described in the present embodiment, the above-described function is electronically performed when the pressure conversion valve 63c is controlled electronically by a separate controller (not shown). Control is possible. 4 is a diagram illustrating a control method when the pressure conversion valve 63c described above is converted to the electronic control. The unit of the vertical axis may be the opening amount when the pressure conversion valve 63c is mechanical. In the figure, the magnitude of the electronic signal controlling this is expressed in mA.

On the other hand, the above-described closed circuit 30 is provided with a flushing valve (flushing valve) (33). The flushing valve 33 is for draining the heated hydraulic oil of the closed circuit 30 when new hydraulic oil is supplied to the first and

second driving passages

31 and 32 by the charging pump 50. More specifically, the flushing valve 33 is driven by the hydraulic pressure of the flow path in which a large pressure is formed among the first driving flow path 31 and the second driving flow path 32. For example, it is assumed that hydraulic oil is supplied to the steering actuator 10 through the first driving passage 31 and hydraulic oil of the steering actuator 10 is discharged to the hydraulic pump 20 through the second driving passage 32. In this state, when a load is applied to the steering actuator 10 so that the pressure of the first driving channel 31 becomes greater than the pressure of the second driving channel 32, the flushing valve 33 is the second driving channel. The operating oil of 32 is converted to drain. The opposite situation is also the same except that the hydraulic oil of the first driving channel 32 is drained.

As described above, the charging pump 50 is a pump for supplementing the flow rate to the closed circuit 30 drained by the driving of the flushing valve 33. Since the hydraulic oil of the closed circuit 30 circulates through the first and

second driving passages

31 and 32 and the hydraulic pump 20 and the steering actuator 10, it is considered that no additional hydraulic oil is required. However, since the hydraulic oil is drained through the flushing valve 33 or the like, it is necessary to supply additional hydraulic oil by the charging pump 50. To this end, the charging pump 50 in this embodiment is always driven in conjunction with an engine (not shown) like the hydraulic pump 20. The hydraulic oil thus produced is supplied to the closed circuit 30 through the hydraulic oil replenishment line 39 when the pressure of the closed circuit 30 is lowered by a predetermined level or more.

On the other hand, the charging pump 50 in this embodiment supplies hydraulic oil for driving the swash plate drive cylinder 61. To this end, the charging pump 50 supplies the working oil to the inlet side of the swash plate control valve 62 through the second supply line 52. The hydraulic oil waiting for the swash plate control valve 62 is a power for driving the swash plate 21 of the hydraulic pump 20 according to the signal pressure transmitted from the first and second

steering signal lines

41 and 42. Used.

Meanwhile, according to the first embodiment of the present invention, the hydraulic oil of the charging pump 50 is also supplied to the steering unit 40 through the first supply line 51 as described above. Accordingly, it is not necessary to provide a separate pump for driving the steering unit 40 and the swash plate control unit 60, it is possible to simplify the system as a whole.

The hydraulic fluid discharged from the charging pump 50 is connected to the tank T through a drain line connected to the hydraulic oil replenishment line 39 when the steering means 45 is not operated or a flow rate is not supplied to the closed circuit 30. Drain).

In the first embodiment, the relief valve is applied as the pressure conversion valve 63c. However, various pressure conversion valves 63c may be used as long as the pressure of the drawing line 63a can be increased in proportion to the flow rate. The pressure conversion valve 63c has an override characteristic as shown in FIG. 4 for the stroke control of the swash plate control valve 62 as described above. Referring to FIG. 4, the pressure P on the vertical axis is the pressure of the lead line 63a, and the horizontal axis represents the operating speed of the steering means 45 per minute. When the steering means 45 is a steering handle, it represents the rotational speed of the handle, and when the steering means 45 is a steering lever, the operating speed of the lever. Since the flow rate of the hydraulic oil discharged from the steering unit 40 increases when the operating speed of the steering means 45 increases, the operating speed of the steering means 45 on the horizontal axis may be regarded as the discharge flow rate of the steering unit 40. have. In addition, in Embodiment 1, since the discharge flow volume of the steering unit 40 is all drained through the pressure conversion valve 63c, the horizontal axis of FIG. 4 may be regarded as the flow rate drained through the pressure conversion valve 63c.

Meanwhile, reference numeral 70 in FIG. 1 is a main relief valve for preventing the pressure of the closed circuit 30 from rising above the allowable pressure.

Hereinafter, the operation of the steering apparatus having the configuration as described above will be described in detail.

First, when the operator operates the steering means 45 in one direction in the state as shown in FIG. 1, the steering unit 40 is converted to discharge hydraulic oil to the first steering signal line 41. At this time, the discharge flow rate of the steering unit 40 is determined by the operating speed of the steering means 45. Then, the flow rate discharged to the first steering signal line 41 is drained through the pressure conversion valve 63c through the lead-out line 63a. At this time, the pressure of the first steering signal line 41 and the drawing line 63a is increased in proportion to the flow rate passing through the pressure conversion valve 63c, that is, the flow rate discharged from the steering unit 40. Therefore, the pressure of the first steering signal line 41 rises in proportion to the operation amount of the steering means 45, and the elevated signal pressure is applied to the first hydraulic pressure part 62a of the swash plate control valve 62. . On the other hand, the second hydraulic pressure unit 62b is connected to the tank T through the second steering signal line 42 and the steering unit 40, so that a signal pressure having a low pressure equal to that of the tank T is formed. Accordingly, the swash plate control valve 62 is converted to one side to communicate the second supply line 52 with the first chamber 61a of the swash plate driving cylinder 61, and the second chamber 61 b of the swash plate driving cylinder 61. ) Is in communication with the tank (T). As a result, the swash plate driving cylinder 61 is driven to one side to incline the swash plate 21 of the hydraulic pump 20 in one direction.

Then, the hydraulic pump 20 sucks the hydraulic oil of the second drive passage 32 and discharges it to the first drive passage 31. As a result, the hydraulic oil discharged from the hydraulic pump 20 is supplied to the steering actuator 10 through the first driving channel 31, and the hydraulic oil of the steering actuator 10 is discharged to the second driving channel 32. Thus, the steering actuator 10 is driven in one direction.

On the other hand, when the operator operates the steering means 45 in the other direction, the steering unit 40 is converted to discharge the hydraulic oil to the second steering signal line 42. Then, the flow rate discharged to the second steering signal line 42 is drained through the drawing line 63a and the pressure conversion valve 63c. At this time, the pressure of the second steering signal line 42 and the drawing line 63a is increased in proportion to the flow rate discharged from the steering unit 40. Therefore, the pressure of the second steering signal line 42 rises in proportion to the operating speed of the steering means 45, and the elevated signal pressure is applied to the second hydraulic pressure portion 62b of the swash plate control valve 62. do. On the other hand, the first hydraulic pressure unit 62a is connected to the tank T through the first steering signal line 41 and the steering unit 40, so that a signal pressure having a low pressure equal to the pressure of the tank T is formed. Accordingly, the swash plate control valve 62 is converted to the other side to communicate the second supply line 52 with the second chamber 61 b of the swash plate drive cylinder 61, and thus the first chamber 61 a of the swash plate drive cylinder 61. ) Is in communication with the tank (T). As a result, the swash plate driving cylinder 61 is driven to the other side to drive the swash plate 21 of the hydraulic pump 20 in the other direction.

Then, the hydraulic pump 20 sucks the hydraulic oil of the first drive passage 31 and discharges it to the second drive passage 32. Then, the hydraulic oil is supplied to the steering actuator 10 through the second driving passage 32, the hydraulic oil of the steering actuator 10 is discharged to the first driving passage 31, and the steering actuator 10 is driven in the other direction. do.

During the operation process as described above, when the external force is transmitted to either one of the first and

second drive passages

31 and 32 through the steering actuator 10, the pressure of the hydraulic oil is excessively increased, the relief valve 70 ) Is switched to drain the hydraulic oil.

As such, by connecting the steering actuator 10 and the hydraulic pump 20 through the first and

second drive passages

31 and 32, the steering circuit can be simplified, thereby reducing costs and pressure loss. It is possible to reduce the energy consumption.

Example 2

With reference to FIG. 2, a steering apparatus for a construction machine according to Embodiment 2 of the present invention will be described, but will be mainly described with respect to the difference with Embodiment 1. FIG. In the second embodiment, unlike the first embodiment, the pump control unit, more specifically, the swash plate control valve 162 is characterized in that the electronic control. In Example 1, the flow rate of the hydraulic oil discharged from the steering unit 40 is determined by the operating speed and the operating direction of the steering means 45, so that the switching amount of the swash plate control valve 162 is determined. However, in the second embodiment, an electronic signal corresponding to the driving of the steering means 45 is generated by the sensor 45a and input to the VCU 100, which is an electronic controller. In addition, the swash plate control valve 162 is also changed to the electromagnetic proportional control valve (EPPR) form is subjected to the control of the VCU (100). Accordingly, the swash plate 21 of the hydraulic pump 20 is driven corresponding to the input signal of the sensor 45a. According to this embodiment, the steering of the equipment may not only correspond to the operation of the steering means 45 but also may be adjusted by other information affecting the operation of the equipment. For example, in the present embodiment, the steering angle may be adjusted in consideration of information 100a such as the engine speed input from the engine controller ECU and the actual driving speed of the vehicle input from the transmission controller TCU. In addition, the feedback of the position of the swash plate driving cylinder 61 can be controlled in the VCU 100 so that the steering of the vehicle is made exactly as desired by the driver to reflect it to the steering of the vehicle. In addition, when the electronic steering lever 49 or the like is provided as an optional feature, not only the steering is controlled by the signal input by the electronic steering lever 49 but also the steering means 45 and the operation of the electronic steering lever 49. Various additional features can be realized, such as automatically determining priorities for.

When the electronic system is configured as described above, the override function of FIGS. 3 and 4 described above can be easily implemented. In addition, it is possible to control the steering speed and the steering amount by distinguishing the fine operation and the normal operation shown in FIGS. 3 and 4. The distinction between normal operation and fine operation may be automatically determined by monitoring the operation of the steering means 45, but may be configured so that the driver can select it when necessary. No matter how configured, the control signal is converted and output from the VCU 100 so that the swash plate driving cylinder 61 is controlled so that the driver can control the steering angle and the steering speed more precisely than in the case of fine manipulation.

On the other hand, in the electronic system as in the present embodiment, a means for restraining the rotation range of the steering means 45 and maintaining the neutral state when the steering means 45 is not operated is further required. However, by using a known technique such as a mechanical device using an elastic body or an electric device having a force feed-back function, the steering means (an additional function of the steering unit 40 (see FIG. 1) described in the foregoing embodiment) 45) can maintain the rotation range constraint and maintain the neutral state. Therefore, in order to avoid the complexity of the drawings, these parts are not separately described, but it may be considered that the above-described functions may be equipped with various known techniques described above.

The technical idea should not be interpreted as being limited to the above-described embodiment of the present invention. Various modifications may be made at the level of those skilled in the art without departing from the spirit of the invention as claimed in the claims. Therefore, such improvements and modifications fall within the protection scope of the present invention, as will be apparent to those skilled in the art.

The invention can be applied to a variety of construction machinery using hydraulic steering actuators, such as excavators and wheel loaders.

Claims

Steering actuator 10;

A hydraulic pump 20 capable of discharging hydraulic oil in both directions by driving of a swash plate;

A pair of drive flow paths 31 and 32 connecting the steering actuator 10 and the hydraulic pump 20 to form a closed circuit;

And a pump control unit (60, 160) for controlling the swash plate (21) of the hydraulic pump (20) by receiving a signal corresponding to the driver's steering means (45) operation,

The pump control unit (60, 160),

One side is connected to the swash plate 21, the swash plate driving cylinder 61 for driving the supply of the operating oil to change the inclination angle of the swash plate to convert the discharge amount and the discharge direction of the hydraulic pump; And

And a swash plate control valve 62 which receives a signal corresponding to an operation of the steering means 45 of the driver and is switched to control a supply amount and a supply direction of the hydraulic oil supplied to the swash plate driving cylinder 61. Steering equipment of construction machinery.
The method of claim 1,

And a charging pump 50 which replenishes the hydraulic oil of the pair of driving passages 31 and 32 by discharging the hydraulic oil to the replenishment line 39 connected to the pair of driving passages 31 and 32. ,

The charging pump 50 is further connected to the swash plate control valve 62 through the second supply line 52, so that the supply of hydraulic oil is also supplied to the swash plate drive cylinder 61 via the swash plate control valve 62. Steering device for a construction machine, characterized in that possible.
The method according to claim 1 or 2,

One side is connected to the operation means 45, the other side is capable of supplying hydraulic oil to the hydraulic pressure section (62a, 62b) of the swash plate control valve 62 through the first and second steering signal lines (41, 42) A steering unit 40 connected to the driver so as to switch the swash plate control valve 62 in response to an operation of the steering unit 45 of the driver.

Pressure of the hydraulic oil applied to the hydraulic pressure parts 62a and 62b of the swash plate control valve 62 in proportion to the flow rate discharged from the steering unit 40 in the first and second steering signal lines 41 and 42. Steering device for a construction machine, characterized in that the pressure conversion unit (63) for gradually varying.
The pressure conversion unit (63) according to claim 3,

The first and second steering signal lines 41 and 42 are installed to connect the tank, and the first and second steering signal lines 41 and 42 are installed to adjust the flow rate drained to the tank in proportion to the flow rate of the hydraulic oil discharged from the steering unit 40. And a pressure conversion valve (63c) for varying the pressure in the second steering signal line (41) (42).
The method of claim 3, wherein

The steering unit 40 further includes a first supply line 51 connecting the charging pump 50 and the steering unit 40 to control the hydraulic oil supplied from the charging pump 50 to control the swash plate. Steering device for a construction machine, characterized in that the supply to the control valve (62).
The method of claim 1,

A sensor (45a) for outputting operation information corresponding to the operation amount and the operation direction of the steering means (45); And

And a controller (VCU, 100) for outputting a control signal in response to the operation information of the steering means 45 input from the sensor 45a.

The swash plate control valve (162) is a steering apparatus of the construction machine, characterized in that the drive is controlled by the control signal output from the controller (100).