JP7444672B2 - crane - Google Patents

Description

The present invention relates to a crane.

Techniques for arbitrarily changing the swinging characteristics of a crane are known. For example, Patent Document 1 describes, "a hydraulic pump, a swing hydraulic motor driven by pressure oil from the hydraulic pump, an operating member for inputting a swing command, and a swing motor driven by a hydraulic pump according to the amount of operation of the operating member. It is equipped with a directional control valve that controls the flow of pressure oil to the hydraulic motor, and a changing means that arbitrarily changes at least one of starting characteristics and stopping characteristics.Bleed-off control is performed by a control signal from the controller to the electromagnetic proportional valve. By switching the valves, the amount of pressure oil supplied to the swing hydraulic motor is controlled based on the starting characteristics during the start operation, and the amount of pressure oil supplied to the swing hydraulic motor during the stop operation is controlled based on the stop operation. ” (see summary).

Japanese Patent Application Publication No. 2008-143635

However, in Patent Document 1, the bleed-off control valve is switched to control the amount of pressure oil supplied to the swinging hydraulic motor, so if the discharge flow rate of the hydraulic pump changes, the swinging characteristics of the crane may become unstable. There is.

Therefore, an object of the present invention is to provide a crane that can obtain stable turning characteristics.

In order to achieve the above object, a typical present invention includes an engine, a main pump driven by the engine, a tank for storing hydraulic oil, and a swing driven by the pressure oil discharged from the main pump. a directional control valve that is activated by operation of an operating device and controls the flow direction of pressure oil supplied from the main pump to the swing hydraulic motor, and a differential pressure across the directional control valve is set in advance. a flow rate control valve that adjusts the flow rate of pressure oil supplied from the main pump to the directional control valve so that the flow rate approaches the set target value; It is provided on an oil path that branches from an oil path that connects to the directional control valve and is connected to the tank, and is capable of returning the pressure oil discharged from the main pump to the tank side. The invention is characterized in that the target value is changed in accordance with the amount of operation of the operating device, regardless of the rotation speed.

According to the present invention, stable turning characteristics can be obtained. Note that problems, configurations, and effects other than those described above will be made clear by the description of the embodiments below.

FIG. 1 is a side view of a crane according to an embodiment of the present invention. FIG. 2 is a configuration diagram of a hydraulic circuit that drives a swing hydraulic motor. It is a figure which shows the relationship between the operation amount of a swing operation lever, and the setting differential pressure of a flow rate control valve. FIG. 3 is a diagram showing a screen of a display panel. FIG. 6 is a diagram showing the relationship between the operation amount of the swing operation lever and the set differential pressure of the flow rate control valve.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view of a crane according to an embodiment of the present invention. The crane according to the present embodiment includes a traveling body 101, a rotating body 103 rotatably mounted on the traveling body 101 via a rotating device 102, and a boom 104 attached to the tip of the rotating body 103 so as to be able to raise and lower. and a driver's cab 108. The rotating body 103 is rotated in the left-right direction by the rotating device 102 at a desired speed. This swing device 102 includes a swing hydraulic motor 20 (see FIG. 2).

A hoisting drum 105 is mounted on the revolving body 103, and a hoisting rope 106 is wound up or let out by driving the hoisting drum 105, and the suspended load is raised and lowered via a hook 107 suspended from the tip of the boom 104. . The operator's cab 108 is provided with a swing operation lever (operation device) 35 for the operator to operate the swing structure 103, a controller 30 for controlling the crane, a display panel 31, etc. (see FIG. 2). This turning operation lever 35 is, for example, an electric lever. Of course, the turning operation lever 35 may be a hydraulic lever.

FIG. 2 is a configuration diagram of a hydraulic circuit that drives the swing hydraulic motor 20. The hydraulic circuit shown in FIG. 2 includes a main pump 11, a pilot pump 12, a swing hydraulic motor 20, a direction control valve 15, a flow control valve 17, a pressure control valve 18, and a relief valve 16. . In FIG. 2, L1 to L8 indicate oil passages, and E1 to E5 indicate electrical wiring. In addition, the code|symbol 25 is a tank which stores hydraulic oil.

The main pump 11 is driven by the engine 10 and supplies pressure oil to the directional control valve 15. The discharge flow rate of the main pump 11 is adjusted by a regulator (not shown). The main pump 11 is a variable displacement hydraulic pump. Pilot pump 12 is driven by engine 10 and supplies pressure oil to pressure control valve 18 . The pilot pump 12 is a fixed capacity hydraulic pump. Note that the rotation speed of the engine 10 is controlled based on the amount of operation of an accelerator grip (not shown) operated by the operator.

The swing hydraulic motor 20 is driven by pressure oil discharged from the main pump 11. The direction control valve 15 controls the flow direction and flow rate of pressure oil supplied to the swing hydraulic motor 20. By switching the position (spool position) of the direction control valve 15, the swing hydraulic motor 20 rotates forward or reverse.

The directional control valve 15 has input sections 15a and 15b on the left and right sides thereof into which pilot signals (electrical signals) are input. When the swing operation lever 35 is operated, pilot signals Pl and Pr are generated by the controller 30 according to the amount of operation. The pilot signals Pl and Pr are input to the input sections 15a and 15b via electric wiring E1 and E2, respectively, and the position of the directional control valve 15 is switched.

Specifically, the directional control valve 15 is normally in the neutral position O, and when the pilot signal Pl is input to the input section 15a, it switches to the left position A, and the pilot signal Pr is input to the input section 15b. and switches to right position B.

When the directional control valve 15 is in the neutral position O, the pressure oil discharged from the main pump 11 flows from the oil path L1 to the oil path L5 and returns to the tank 25. When the direction control valve 15 is switched to the left position A, the pressure oil discharged from the main pump 11 flows from the oil path L1 to the oil path L2 to rotate the swing hydraulic motor 20 in the normal direction. The pressure oil discharged from the swing hydraulic motor 20 flows through the oil path L3 and the oil path L5 in order and returns to the tank 25.

On the other hand, when the direction control valve 15 is switched to the right position B, the pressure oil discharged from the main pump 11 flows from the oil path L1 to the oil path L3 to reverse the rotation hydraulic motor 20. The pressure oil discharged from the swing hydraulic motor 20 flows through the oil path L2 and the oil path L5 in order and returns to the tank 25.

The flow rate adjustment valve 17 is provided on an oil passage L4 that branches from an oil passage L1 that connects the main pump 11 and the direction control valve 15 and is connected to the tank 25. The flow control valve 17 is normally held in a closed direction by a spring 17a. A pressure Ps on the discharge side of the main pump 11, a pressure Pc on the downstream side of the directional control valve 15, and a pressure Pv on the downstream side of the pressure control valve 18 act on the flow rate adjustment valve 17, respectively. Specifically, the pressure Ps acts in the direction to open the flow rate control valve 17, and the pressure Pc and the pressure Pv act in the direction to close the flow rate control valve 17.

Therefore, the flow control valve 17 opens and closes depending on the balance between the differential pressure across the direction control valve 15 (the difference between the pressure Ps and the pressure Pc) and the pressure Pv of the pressure oil introduced from the pressure control valve 18. Note that the pressure Pc is affected by the pressure loss of the directional control valve 15 and is therefore lower than the pressure Ps.

The pressure control valve 18 is provided in the oil passage L6 through which the pressure oil discharged from the pilot pump 12 flows. In a normal state, the pressure control valve 18 is held at a position where the oil passage L7 and the oil passage L8 communicate with each other, and the pressure Pv is equal to the tank pressure. When a control signal is input from the controller 30 to the pressure control valve 18 via the electric wiring E5, the pressure control valve 18 is switched to a position where the oil passage L6 and the oil passage L7 communicate with each other in accordance with the control signal. As a result, pressure oil from the pilot pump 12 is introduced into the flow control valve 17.

The relief valve 16 limits the upper limit of the discharge pressure of the main pump 11 to a set pressure. Therefore, the pressure within the hydraulic circuit shown in FIG. 2 does not exceed the set pressure of the relief valve 16.

Although not shown, the controller 30 includes a CPU that performs various calculations, a storage device such as a ROM or HDD that stores programs for executing calculations by the CPU, a RAM that serves as a work area when the CPU executes programs, and It consists of hardware that includes a communication interface that is an interface for transmitting and receiving data with other devices, and software that is stored in a storage device and executed by a CPU. Each function of the controller 30 is realized by the CPU loading various programs stored in the storage device into the RAM and executing them.

When an operation command is input from the swing operation lever 35 via the electric wiring E3, the controller 30 generates a control signal according to the operation command, and outputs the control signal to the pressure control valve 18. For example, in the present embodiment, the controller sends a control signal such that the larger the operating amount of the swing operation lever 35, the larger the set pressure of the pressure control valve 18 (the value of the pressure Pv acting on the flow rate control valve 17 becomes larger). Generated by 30. Therefore, when the amount of operation of the swing operation lever 35 is small, the setting (target value) of the pressure difference across the direction control valve 15 can be made small, and when the amount of operation of the swing operation lever 35 is large, the setting of the pressure difference across the direction control valve 15 can be made small. (target value) can be increased.

Of course, the controller 30 may generate a control signal that makes the set pressure of the pressure control valve 18 constant regardless of the amount of operation of the swing operation lever 35.

Further, a display panel 31 is connected to the controller 30 via electric wiring E4. The display panel 31 is, for example, a touch-type liquid crystal panel, and the operator can perform touch operations to check various settings and conditions of the crane.

(Operation of hydraulic circuit)
Next, the operation of the hydraulic circuit according to this embodiment will be explained. Here, a case where the operator operates the turning operation lever 35 in the left turning direction in order to turn the rotating structure 103 to the left will be described as an example.

When the operator operates the swing operation lever 35, an operation command from the swing operation lever 35 is input to the controller 30. Controller 30 outputs pilot signal Pl to input section 15a based on the operation command. Then, the direction control valve 15 switches to the left position A, pressure oil from the main pump 11 is supplied to the swing hydraulic motor 20, the swing hydraulic motor 20 is rotationally driven, and the swing body 103 starts to swing to the left. .

Further, the controller 30 generates a control signal for operating the pressure control valve 18 according to the input operation command, and outputs the control signal to the pressure control valve 18.

The pressure control valve 18 operates according to the input control signal so that the oil passage L6 and the oil passage L7 communicate with each other, and the pressure oil discharged from the pilot pump 12 is introduced into the flow rate adjustment valve 17.

As a result, the flow rate control valve 17 operates in the closing direction due to the action of the pressure Pv on the downstream side of the pressure control valve 18, and the differential pressure across the direction control valve 15 changes to a set differential pressure (predetermined pressure) corresponding to the pressure Pv. target value). Since the pressure Pv is determined according to the amount of operation of the swing operation lever 35, the differential pressure across the direction control valve 15 becomes a target value according to the amount of operation of the rotation operation lever 35.

To explain in more detail, since the pressure Pv corresponding to the operation amount of the swing operation lever 35 acts on the flow rate adjustment valve 17, if the differential pressure across the direction control valve 15 is smaller than the sum of the pressure Pv and the spring 17a, The flow control valve 17 does not operate in the opening direction, but operates in the closing direction. As a result, the differential pressure across the direction control valve 15 remains as it is. When the differential pressure across the directional control valve 15 exceeds the total value of the pressure Pv and the spring 17a, the flow control valve 17 operates in the opening direction, so that the differential pressure across the directional control valve 15 reaches a preset target. value, that is, the total value of the pressure Pv and the biasing force of the spring 17a. Since the set pressure Pv of the pressure control valve 18 changes according to the amount of operation of the swing operation lever 35, the differential pressure across the direction control valve 15 also approaches the target value according to the amount of operation of the rotation operation lever 35. controlled.

In this way, under the differential pressure across the directional control valve 15 that is controlled to approach a preset target value in accordance with the operation of the swing operation lever 35, the desired flow rate of pressure oil is maintained at the rotation speed of the engine 10. Regardless, it is supplied to the swing hydraulic motor 20.

(effect)
As described above, according to the present embodiment, the differential pressure across the directional control valve 15 approaches a preset target value regardless of changes in the discharge flow rate of the main pump 11 or changes in the rotational speed of the engine 10. controlled by. As a result, pressure oil is stably supplied from the main pump 11 to the swing hydraulic motor 20 at a flow rate corresponding to the differential pressure across the directional control valve 15 . Therefore, for example, even if the rotational speed of the engine 10 is increased in order to drive the hoisting drum 105 at high speed, the turning speed of the revolving structure 103 does not change, so that stable turning characteristics of the crane can be obtained. Moreover, the combined operability of the crane is improved.

Further, since the set differential pressure of the flow rate control valve 17 can be arbitrarily adjusted by a control signal sent from the controller 30 to the pressure control valve 18, it is possible to realize crane operability that suits the operator's preference.

In this embodiment, the setting differential pressure of the flow rate regulating valve 17 is set to increase as the amount of operation of the swing operation lever 35 increases. Therefore, when the swing operation lever 35 is operated with a small setting (target value) of the differential pressure across the direction control valve 15, the bypass flow rate of the flow rate control valve 17 (flow rate flowing through the flow rate control valve 17) increases, The torque that drives the turning hydraulic motor 20 increases gradually, and gradual acceleration characteristics are obtained.

On the other hand, when the swing operation lever 35 is operated with a large setting of the differential pressure across the direction control valve 15, the bypass flow rate of the flow control valve 17 decreases, and the increase in the torque that drives the swing hydraulic motor 20 decreases. becomes larger, and rapid acceleration characteristics are obtained.

In this way, according to the present embodiment, it is possible to stably obtain any turning characteristic according to the operator's preference. Another advantage is that the crane can be improved in operability with a simple configuration that requires only the pressure control valve 18.

(Modified example)
In the embodiment described above, a plurality of modes M1 to M3 having different control characteristics (operating characteristics) of the flow rate regulating valve 17 are preset in the controller 30, and when the operator selects his/her favorite mode on the display panel 31, the flow rate control valve 17 is set in advance. The control valve 17 may be configured to operate according to the selected mode.

For example, as shown in FIG. 3, three modes M1 to M3 are provided in advance in which the set differential pressure of the flow rate control valve 17 differs depending on the amount of operation of the swing operation lever 35. Modes M1 to M3 each have a control characteristic in which the larger the operating amount of the swing operation lever 35 is, the larger the set differential pressure of the flow rate regulating valve 17 is. The pressure is different.

Then, as shown in FIG. 4, when the operator touches one of the modes M1 to M3 on the mode setting screen of the display panel 31, the selected mode is output from the display panel 31 to the controller 30. Controller 30 generates a control signal for pressure control valve 18 according to its mode.

For example, when comparing mode M1 and mode M3, the set differential pressure of the flow rate control valve 17 is larger in mode M1 than in mode M3 for the same amount of operation of the swing operation lever 35. Therefore, when mode M1 is selected, the differential pressure across the direction control valve 15 becomes larger, so even with the same operation amount of the swing operation lever 35, the flow rate of the pressure oil supplied to the swing hydraulic motor 20 becomes larger, and The rotating body 103 can be rotated at high speed.

According to this modification, it becomes possible to perform a turning operation that is even more tailored to the operator's preference.

Note that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the gist of the present invention, and all technical matters included in the technical idea described in the claims are This is the object of the present invention. Although the embodiments described above are preferred examples, those skilled in the art can realize various alternatives, modifications, variations, or improvements based on the contents disclosed in this specification. These are within the scope of the appended claims.

For example, instead of modes M1 to M3 in FIG. 3, modes M4 to M6 may be used in which the set differential pressure of the flow control valve 17 changes stepwise with respect to the operation amount of the swing operation lever 35, as shown in FIG. can. Further, the controller 30 stores data that is a map of the relationship between the operation amount of the swing operation lever 35 and the set differential pressure of the flow rate control valve 17, and the controller 30 controls the operation of the pressure control valve 18 based on the data. It may be controlled.

Further, instead of the touch operation on the display panel 31, a dedicated switch or dial for selecting a mode may be separately provided. These modes may be configured so that the operator can add, change, or delete them as desired.

Although a crawler crane has been illustrated as an example of a crane, the present invention is not limited to this and can be applied to other mobile cranes such as wheel cranes, truck cranes, rough terrain cranes, and all-terrain cranes, as well as tower cranes and ceiling cranes. Applicable to all cranes such as cranes, jib cranes, retraction cranes, stacker cranes, gantry cranes, and unloaders.

10 Engine 11 Main pump 12 Pilot pump 15 Direction control valve 17 Flow rate adjustment valve 18 Pressure control valve 20 Hydraulic motor for swing 35 Operation lever (operation device)
30 controller 31 display panel

Claims (4)

engine and
a main pump driven by the engine;
A tank for storing hydraulic oil,
a swing hydraulic motor driven by pressure oil discharged from the main pump;
a directional control valve that is activated by operation of an operating device and controls the flow direction of pressure oil supplied from the main pump to the swing hydraulic motor;
A crane comprising: a flow rate adjustment valve that adjusts the flow rate of pressure oil supplied from the main pump to the directional control valve so that the differential pressure across the directional control valve approaches a preset target value;
The flow rate adjustment valve is provided on an oil path that branches from an oil path connecting the main pump and the directional control valve and is connected to the tank, and controls pressure oil discharged from the main pump to the tank side. It is possible to return to
A crane characterized in that the target value is changed in accordance with the amount of operation of the operating device, regardless of the rotation speed of the engine. The crane according to claim 1,
A crane characterized in that the target value is changed to become larger as the amount of operation of the operating device becomes larger. The crane according to claim 1 or 2,
A plurality of modes with different control characteristics of the flow rate regulating valve are set in advance,
A crane characterized in that the target value is changed according to the selected mode. The crane according to any one of claims 1 to 3,
further comprising a pilot pump driven by the engine,
A crane characterized in that pressure oil discharged from the pilot pump is introduced into the flow rate control valve at a pressure corresponding to an operation amount of the operating device, and acts in a direction to close the flow rate control valve.

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