JP3531903B2 - Small excavator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a small hydraulic excavator used for civil engineering work, construction work and the like. 2. Description of the Related Art At present, there is a small-sized hydraulic excavator to which a bucket-type working unit is attached, in which a blade is attached to perform a dozer operation. In addition to the vertical movement of the blade, there is a configuration in which the blade can be transformed into a tilt posture in which the right and left heights of the blade are different and an angle posture in which the front and rear positions are different in the left and right. Such a posture change is performed by the expansion and contraction operation of each of the hydraulic cylinders for tilt and angle provided respectively. By the way, in small hydraulic excavators, hydraulic couplers (joints) for external attachments are those for operating hydraulic oil from the main hydraulic pump and those for pilot hydraulic oil from the sub hydraulic pump due to simplification of equipment. Generally, only one set is provided. [0003] The functions of tilting and angle of the blade as described above are generally treated as optional. Therefore, the external hydraulic coupler is used, A selector valve for selecting and switching the supply of pressurized oil to the angle and tilt hydraulic cylinders is further externally provided. As a result, in a small-sized hydraulic excavator, a first pilot pressure oil switching valve for switching a main switching valve to supply working pressure oil to the selector valve, and a second pilot pressure switching valve for switching a selector valve are provided. A pressure oil switching valve is provided, and these pilot pressure oil switching valves are switched by different operating means. Therefore, there is a problem that the operation is troublesome, complicated and inferior in workability. Further, when switching from the tilt function to the angle function, if the switching operation of the second pilot pressure oil switching valve is performed after the switching operation of the first pilot pressure oil switching valve, the selector is switched with respect to the switching of the main switching valve. Timing delay occurs when switching valves,
For this reason, the operating pressure oil is supplied to the tilt hydraulic cylinder after being supplied to the tilt hydraulic cylinder, and there is also a problem that a smooth transformation is not performed. There is a problem to do. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has been made with the object of solving these problems. The upper revolving unit is provided so as to be pivotable. In a small hydraulic excavator having a lower traveling body, a blade that vertically moves up and down by operation of an operation lever arranged in a driving control section, the blade is provided with a tilt hydraulic cylinder and an angle hydraulic cylinder, and a tilt posture, In adding the function of transforming to the angle posture, a selector valve for selectively supplying hydraulic pressure oil to each of the tilt and angle hydraulic cylinders, and a selector valve for supplying hydraulic pressure oil to the selector valve A main switching valve,
The main switching the first Pyro <br/> Tsu preparative switching switch valve for switching the valve, and a second pilot changeover switch valve for switching the selector valve, the first and second pilot switching Two tilt operation switches and two angles operated to output a valve switching command
And a le manipulation switch, one either of the operation switches
Operate one of the two to set the second path according to the set delay time.
Wait for the pilot valve to be switched
Selective switching of pilot switching valve
The corresponding tilt or angle movement
Initially, hydraulic oil is not supplied to the hydraulic cylinder before switching.
It is a small hydraulic excavator you have odd. With this configuration, the first and second pilot switching valves can be switched by operating the operation switch, so that the operability can be improved , and at the time of tilt-angle switching,
The first pilot pressure oil switching valve is the second pilot pressure oil
Avoid the problem of switching before the switching valve
Wear. Next, an embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 denotes a small hydraulic excavator body, which is formed of a crawler-type lower traveling body 2, an upper revolving body 3, and an upper revolving body 3, which are rotatably provided on the lower traveling body 2. It is the same as in the related art that it is composed of various member devices such as a driving operation unit 4 to be operated and a bucket working unit 5 extending from the upper swing body 3. Reference numeral 6 denotes a pair of left and right arms whose base ends are pivotally supported on the lower traveling body 2 so as to be vertically swingable. A bracket 7 is integrally connected between the distal ends of the arms 6. .
A tilt support shaft 8 whose axis is oriented in the front-rear direction is rotatably supported on the lower side of the center front portion of the bracket 7 in the left-right direction so as to be rotatable around the axis. , A blade 10 via an angle support shaft 9 whose axis is oriented vertically.
A bracket 10a provided on the rear surface is pivotably supported in the direction around the axis of the angle support shaft 9. Reference numerals 11R and 11L denote left and right angle hydraulic cylinders.
In each case, the base end corresponds to each arm 6 via the support shaft 11a.
The front end portion is swingably supported on the left and right back surfaces of the blade 10 via a support shaft 11b. As will be described later, when the angle cylinder 11 reciprocally expands and contracts, the blade 10 swings back and forth with the angle support shaft 9 as a fulcrum. It is configured to have an angle posture inclined forward and backward. On the other hand, reference numeral 12 denotes a hydraulic cylinder for tilting. The hydraulic cylinder 12 has a support shaft 12a provided on the bracket 7 with its base end positioned concentrically with respect to the support shaft 9 for angle. While the tip is concentrically positioned with respect to a support shaft 11b that supports one of the angle hydraulic cylinders 11 (the left side in this embodiment). 10 is supported swingably on a support shaft 12b provided on the shaft 10. When the tilt hydraulic cylinder 12 expands and contracts as described later, the blade 10 swings up and down around the tilt support shaft 8 so that the blade 10 can be transformed into a tilt posture. I have. Reference numeral 13 denotes the lower traveling body 2 and the bracket 7
And a hydraulic cylinder for raising and lowering the blade vertically. The hydraulic cylinders 11 and 12 are connected to a selector valve 14 which will be described later, which is attached to the left arm 6 as an external member. The selector valve 14 includes a lower traveling unit 2 and an upper revolving unit. 3 is further connected to a pilot pressure oil coupler 16 and a working pressure oil coupler 17 provided for an optional attachment to a rotary joint 15 provided between them. Reference numeral 18 denotes a blade 1 arranged on the driving section 4.
The operating lever 18 is used to extend and retract the blade lifting hydraulic cylinder 13 by operating the operating lever 18 in the front-rear direction. 4 operation switches for convenience
9, 20, 21 and 22 are provided, of which the operation switches 19 and 20 are set for tilt operation and the operation switches 21 and 22 are set for angle operation. The operation switches 19 to 22 are connected to a control unit 23 configured using a microcomputer or the like, and these switch signals are input to the control unit 23. Based on this , a control signal is output to a first pilot switching valve 24 for tilt or angle operation and a second pilot switching valve 25 for tilt-angle switching described later. The first pilot switching valve 24 is constituted by a three-position switching valve having a neutral position, and is set so that it can be switched to a corresponding valve position by operating the provided left and right operating solenoids 24R and 24L. The second pilot switching valve 25 is constituted by a two-position switching valve having one switching solenoid 25a. And the solenoid 25a
Is set to be switched to the tilt side as will be described later, when receiving the urging force of the return spring 25b. Next, the hydraulic circuits of the angle hydraulic cylinders 11R and 11L and the tilt hydraulic cylinder 12 will be described with reference to FIG. In the figure, Pm is a main hydraulic pump, and Ps is a sub hydraulic pump, each of which is started based on the driving of an engine (not shown). The hydraulic oil discharged from the main hydraulic pump Pm is Is set to be supplied to the selector valve 14 by the switching of the main switching valve 26. The switching of the main switching valve 26 is performed by the pilot cylinder 27.
The pilot cylinder 27 is switched by the first pilot switching valve 24 for tilt or angle operation. The selector valve 14 switches the supply of hydraulic oil to the tilt hydraulic cylinder 12 or the angle hydraulic cylinders 11R and 11L. The switching operation is performed by the switching operation of the second pilot switching valve 25. Is to be executed. That is, when none of the operation switches 19 to 22 is operated, the first pilot switching valve 24 is in the neutral state, and the second pilot switching valve 2 is in the neutral state.
5 is switched to the tilt position side. In this state, the second pilot switching valve 25 is in a state where the pilot pressure oil supply oil passage 14a for the selector valve 14 from the sub hydraulic pump Ps is closed, while the pilot tank oil passage 14b of the selector valve 14 is open. This causes the selector valve 14 to return to the return
The oil passage 14d communicating with the main switching valve 26 under the urging force of c is positioned at a tilt side communicating with the oil passage 14e for supplying hydraulic oil to the hydraulic cylinder 12 for tilt. However, since the main switching valve 26 is in the neutral state, the supply of pressure oil from the main hydraulic pump Pm is not performed, and the tilt operation is not performed. From this state, the tilt operation switch 1
When one of the buttons 9 and 20 is pushed, the operation signal is input to the control unit 23 and the switching control of the pilot switching valves 24 and 25 is performed based on the operation signal. No operation command is output to the switching second pilot switching valve 25,
While the FF state is maintained, an operation command is output to the corresponding one of the solenoids 24R and 24L for the first pilot switching valve 24.
The output is output with a delay of a predetermined delay time T (for example, 0.5 seconds) by a delay circuit 23a built in the control unit 23. When the first pilot switching valve 24 is switched to the corresponding side, the pilot pressure oil is supplied to the pilot cylinder 27, and based on this, the main switching valve 26 is switched to the corresponding side to be opened, and the main hydraulic pump Pm is opened. Is supplied to the side where the hydraulic cylinder for tilt 12 is extended or contracted, whereby the blade 10 is set to change to a tilt position in which one of the left and right is raised upward. On the other hand, the angle operation switch 2
When either one of the control units 1 and 22 is operated, the control unit 23
Is the solenoid 25 of the second pilot switching valve 25
a, the pilot pressure oil supply oil passage 14a of the selector valve 14 is opened, and the pilot pressure oil is supplied from the sub-hydraulic pump Ps. , The selector valve 14 is switched to the angle side position. On the other hand, at the stage when the delay time T has elapsed from the stage at which the switch operation was performed, the first pilot switching valve 24
, An operation command is output to one of the solenoids 24R and 24L on the corresponding side, and the pilot pressure oil from the sub hydraulic pump Ps is supplied to the pilot cylinder 27.
Based on this, the main switching valve 26 is opened to the corresponding side, and the pressure oil from the main hydraulic pump Ps is supplied to the corresponding angle hydraulic cylinders 11R, 11L. It is set so that the angle posture is located at. A throttle valve 28 is provided in the pilot pressure oil supply oil passage 14 a of the selector valve 14.
In order to avoid abrupt switching and perform smooth switching without shock, the delay time T is set to correspond to the switching time (slightly longer than the switching time). . In the embodiment of the present invention configured as described above, when changing the blade 10 to the tilt position or the angle position, the operator operates the operating lever 1.
8 operating switches 19 to provided on the grip 18a
What is necessary is just to select an appropriate one from 22 and perform a push operation, whereby the blade 10 is transformed into a corresponding posture. As described above, in the embodiment of the present invention, by operating any of the operation switches 19 to 22, the first and second pilot switching valves 24 and 25 are switched to the corresponding states. The pilot switch valve 2 is tilted or angled.
One operation switch 19 for selecting the switching between 4 and 25
Since the operations of ~ 22 are sufficient, the operability is improved. In addition, in this embodiment, each of the operation switches 19 to 22 is used to move the blade 10 up and down.
a, the operation for operating the blade 10 is concentrated at the central position, so that the operability is further improved. Further, when the operation switches 19 to 22 are operated, the first pilot switching valve 2 is waited until the second pilot switching valve 25 is switched.
When the angle-tilt operation is switched, the hydraulic cylinder is not supplied to the hydraulic cylinder before the switching at the beginning of the operation, so that the cylinder operation can be performed smoothly. The present invention is not limited to the above-described embodiment, but can be implemented in the second embodiment shown in FIG. In this embodiment, a second pilot switching valve 29 for switching the selector valve 14 is constituted by a three-position switching valve having a neutral position. In this embodiment, the second pilot switching valve 29 is used for switching operation. When the operation switches 19 to 22 are operated, the oil passage of the pilot pressure oil is opened to switch the selector valve 14 to the corresponding side when the operation switches 19 to 22 are operated.
This can also be implemented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a hydraulic shovel. FIG. 2 is a plan view showing a state where an upper swing body is removed. FIG. 3 is a view taken in the direction of arrows AA in FIG. 2; FIGS. 4A and 4B respectively show B in FIG. 2;
-B sectional drawing and CC sectional drawing. FIG. 5 is a perspective view of a blade unit. FIGS. 6A and 6B are a perspective view of an operation lever portion and a perspective view of an operation lever grip portion, respectively. FIG. 7 is a hydraulic circuit diagram of blade attitude control. FIG. 8 is a block diagram illustrating a control state in a control unit. FIG. 9 is a hydraulic circuit diagram of blade attitude control according to the second embodiment. [Description of Signs] 1 Body 2 Lower traveling body 6 Arm 8 Tilt support shaft 9 Angle support shaft 10 Blade 11R Right angle hydraulic cylinder 12 Tilt hydraulic cylinder 14 Selector valve 18 Operation lever 19 Operation switch 23 Control unit 24 First pilot switching valve 25 Second pilot switching valve 26 Main switching valve

Continuation of the front page (56) References JP-A-8-292817 (JP, A) JP-A-9-302727 (JP, A) JP-A-8-85974 (JP, A) JP-A-3-89762 (JP) , U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) E02F 9/22 E02F 9/20

Claims (1)

(57) [Claims 1] A lower traveling body provided with an upper revolving body that is rotatable is provided with a blade that moves up and down by operating an operation lever provided in a driving control unit. In a small-sized hydraulic excavator, a hydraulic cylinder for tilt and a hydraulic cylinder for angle are provided on the blade to add a function of changing to a tilt posture and an angle posture. a selector valve for selection supply, the selector and the main selector valve for the hydraulic oil supply to the valve, said main switching first pilot switching <br/> switch valve for switching the valve When, a second pilot changeover switch valve for switching the selector valve, first, in order to output the switching command of the second pilot switching valve Misao Be
It has two tilt operation switches and two angle operation switches, and operates any one of the operation switches.
Operation, the second pilot depends on the set delay time.
Pyro waiting for switching valve to switch
So that the selection of the cut-off valve is switched.
Switch the corresponding tilt or angle movement at the beginning of operation.
Make sure that pressure oil is not supplied to the hydraulic cylinder before replacement.
Small hydraulic excavators that you are in.