JPH09209408A - Backhoe turning speed controller - Google Patents

Abstract

(57) [Abstract] [Problem] By devising such that the turning speed is automatically reduced when the turning radius is operated in a small state,
Provided is a backhoe which improves the maneuverability by improving the difficulty of soil spillage and bucket positioning operation in a narrow place described above. In a backhoe that employs a load sensing system that controls a pump flow rate to a discharge pressure slightly higher than a load pressure, an adjusting unit that changes and adjusts a differential pressure that is a control reference for the backhoe, and a bucket 7 position with respect to a turning center Q are provided. A bucket position detecting means for detecting is provided, and when the distance between the turning center Q and the turning center Q becomes a first predetermined distance d1 when the bucket 7 is pulled and moved, the turning speed is gradually reduced to a second predetermined distance d2 which is closer to the driving section than that. When the distance from the turning center Q reaches the second predetermined distance when the bucket 7 moves away, the turning speed is rapidly increased to a third predetermined distance d3 closer to the turning center G than the first predetermined distance d1 before deceleration. Return to speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backhoe turning speed control device, and more particularly to a technique for automatically lowering the turning speed when the turning radius of a turning base becomes small due to a change in the attitude of an excavation work device.

[0002]

2. Description of the Related Art In a backhoe, an excavation work device and a swivel base are driven by tilting an operating lever, and the driving speed thereof is generally high when the lever tilting amount is large. In other words, it is possible to move slowly by tilting the operating lever a little and move quickly if tilting a large amount, but a familiar operator usually tilts the operating lever as much as possible for full operation. is there. Therefore, although the drive speed can be changed by adjusting the lever tilt amount or the engine speed, etc., in actual work, the excavation work device and the swivel base are operated at a constant drive speed. It was a thing.

[0003]

When considering excavation work with a backhoe, when excavating the ground with a bucket to scoop the soil, the boom and arms are lifted and lifted while the scooped soil is not dropped and the swing is performed. In many cases, the platform is turned to drop the soil in the bucket on a truck bed. In other words, the excavation site and the scooping soil lowering site are different, and the turning operation is performed in most cases, but this turning operation has some problems.

That is, when the work area is large, the boom is lifted up and down by an amount necessary for the reciprocating movement between the excavation location and the soil unloading location, so that the boom and the arm are not moved in vain. Perform less efficient work. On the other hand, in a narrow place such as an alley in an urban area, a sufficient turning radius is often not obtained, so that the boom is raised to pull the bucket toward the swivel base, and the swinging is performed with a small turning radius.

However, in terms of work efficiency, in many cases, regardless of whether the location is wide or narrow, it is often necessary to drive the bucket at the same time as the pulling operation of the bucket or at the same time during turning. It was difficult to continuously perform the skillful maneuvering of simultaneously pulling and turning while keeping the scooping posture, and the soil tended to fall from the bucket. In particular, in the small turning type backhoe in which the boom moves in parallel offset as shown in Japanese Patent Laid-Open No. 7-237458, the tendency becomes strong.

[0006] In addition, it is preferable that the excavation work device is folded deeply and turned slowly in a narrow place by slowly driving it in view of easiness of maneuvering and positioning operation. It was difficult to control. To this end, when turning in a narrow place where it is relatively difficult to control, it is necessary to add a careful operation such as reducing the amount of tilting of the turning control lever to make it more difficult to control and to reduce efficiency. In some cases, it is better to keep work efficiency without lowering the turning speed.

An object of the present invention is to devise such that the turning speed is automatically reduced when the turning radius is operated in a small state, so that the soil spill in the narrow place and the difficulty of the bucket positioning operation described above can be solved. The point is to provide a backhoe that is improved to improve maneuverability.

[0008]

[Means for Solving the Problems]

[Structure] In the first invention, a bucket position detecting means capable of detecting the bucket position with respect to the turning center of the swivel base is provided, and the turning speed of the swivel base is reduced when the distance between the swivel center and the bucket becomes a predetermined distance or less. The turning hydraulic actuator and the bucket position detecting means are linked together.

According to a second aspect of the present invention, in the first aspect of the present invention, the traveling hydraulic actuator and the bucket position detecting means are linked so that the traveling speed of the machine body is reduced when the distance between the turning center and the bucket becomes a predetermined distance or less. It is characterized by being.

A third aspect of the present invention is a working hydraulic actuator, a variable displacement hydraulic pump, a control valve having a throttle valve for a pressure oil supply path to the hydraulic actuator, a discharge amount per unit time of the hydraulic pump. And a flow rate adjusting mechanism for variably setting the pressure difference between the first oil passage communicating with the lower portion of the pressure oil supply to the throttle valve and the second oil passage communicating with the pressure oil supply port of the control valve. Adjusting means for adjusting the throttle amount or differential pressure of the throttle valve and bucket position detecting means for detecting the bucket position with respect to the swing center of the swivel base. Is provided, and the bucket position detecting means and the adjusting means are linked so that the turning speed of the turning base is reduced when the distance between the turning center and the bucket becomes equal to or less than a predetermined distance. That is, in a backhoe that employs a load sensing system (hereinafter abbreviated as LS / S), the turning speed is automatically reduced in cooperation with a gain control for determining the differential pressure.

A fourth invention is characterized in that, in the first to third inventions, the turning speed of the turntable is gradually reduced when the distance between the turning center and the bucket is equal to or less than a predetermined distance. It is a thing.

According to a fifth aspect of the invention, in the first to third aspects of the invention, when the distance between the swing center and the bucket reaches a predetermined distance when the bucket is moved in a direction approaching the swing center, the second distance is smaller than the predetermined distance. When the swivel speed of the swivel base is gradually reduced until the predetermined distance is reached, and when the distance between the swivel center and the bucket reaches the second predetermined distance when moving in the direction away from the swivel center of the bucket, The acceleration is started so as to return the turning speed to the speed before deceleration, and the absolute value of the acceleration at the speed increase is controlled to be larger than the absolute value of the deceleration at the gradual decrease of the turning speed. It is characterized by being present.

According to the structure of claim 1, since the turning speed is reduced when the distance between the bucket and the turning center becomes a predetermined distance or less, the turning speed is slowed down when the excavation work device is folded deeply. To be done. Therefore, when excavating in a narrow place, if the simultaneous operation of scooping the soil and then turning while excavating the excavation work device is performed, the turning speed will automatically slow down when the turning radius decreases to a certain degree. The low swivel speed improves the swivel stop accuracy of the swivel platform, and the absolute moving speed of the bucket due to the sum of the folding drive speed of the excavation work device and the swivel speed can be slowed down, and soil spill from the bucket can also be prevented. It becomes difficult to occur. Further, since the turning speed is automatically reduced, the troublesomeness of adjusting the tilting amount of the turning operation lever and the trouble of the accelerator down operation for reducing the engine speed unlike the conventional case are eliminated.

According to the second aspect of the present invention, when the distance between the bucket and the turning center becomes a predetermined distance or less, not only the turning speed but also the traveling speed is reduced.
This is effective when operating the aircraft forward or backward to operate on a soil unloading place. That is, the traveling speed is automatically reduced without adjusting the tilt amount of the traveling lever, and the operability such as the accuracy of stopping the bucket at the target position can be improved while maintaining an operating state with no margin for additional operation.

In the case of the one provided with LS / S, its function is
In a state where the pump discharge amount is large, the drive speed of the work hydraulic actuator such as the boom cylinder does not decrease even if the engine speed is reduced. Therefore, in the configuration of claim 3, the adjusting means capable of changing and adjusting the throttle amount or the differential pressure of the throttle valve is provided, and the adjusting means and the bucket position detecting means are linked to each other, whereby the LS / S is adopted. In the backhoe, the control for automatically reducing the turning speed can be performed when the turning radius becomes smaller.

According to a fourth aspect of the present invention, when the distance between the turning center and the bucket becomes equal to or less than a predetermined distance, the speed is not gradually lowered, but is gradually decelerated to reduce the speed. In other words, when decelerating suddenly, the soil in the bucket may be spilled due to the deceleration shock due to inertia, so the deceleration is gently decelerated to eliminate the deceleration shock.

According to a fifth aspect of the invention, a working efficiency improving action is added to the action of the fourth aspect. That is, when the excavation work device that is folded to move the bucket on the truck platform is extended and moved, when the distance between the bucket and the turning center becomes the second predetermined distance, the turning speed is rapidly increased from the viewpoint of work efficiency. It is better to accelerate and return to the original relatively high turning speed, but then there is a possibility of soil spillage due to accelerated shock. Therefore, the hysteresis of the turning speed change is provided so that the acceleration is increased to the extent that the acceleration has an absolute value larger than the absolute value of the deceleration when decelerating the turning speed, thereby preventing soil spillage as much as possible. The work efficiency can be improved as much as possible.

[Effect] In the turning speed control device according to any one of claims 1 to 5, (a) while maintaining a good work efficiency when the work place is wide, there is little soil spillage in a narrow place, In addition, good operability for easy turning operation was realized, and maneuverability of the backhoe could be improved overall.

In the turning speed control device according to the second aspect,
When the distance between the bucket and the turning center becomes less than a predetermined distance, the turning speed and the running speed are slowed down.Therefore, the excavation site and the scooping soil discharge place are relatively distant from each other, and the turning operation and the running operation are required. There is an advantage that the above-mentioned effect (a) can be exhibited even in the work that

In the turning speed control device according to the third aspect,
The above effect (a) can be exhibited even in a backhoe that adopts LS / S.

In the turning speed control device according to the fourth aspect,
When the distance between the bucket and the turning center becomes equal to or less than the predetermined distance, the turning speed is gradually reduced, and in addition to the effect (a), there is an advantage that (b) soil spillage caused by a deceleration shock can be suppressed.

In the turning speed control device according to the fifth aspect,
When the distance between the bucket and the turning center becomes equal to or less than a predetermined distance, the turning speed is gradually decreased, and the reduced turning speed is returned to the original speed relatively quickly.
In addition to (b), there is an effect that soil spillage during extension drive of the excavation work device can be suppressed and work efficiency can be improved so as to improve.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. A small turning type backhoe is shown in FIG. 1, 1 is an excavation work device, 2 is a swivel platform, 3 is a traveling platform, 4 is a crawler traveling device, 28 is a dozer, and the excavation work device 1 is a boom 5. The boom 5 includes an arm 6, a bucket 7, and the like, and the boom 5 has a parallel offset structure in which a base end side boom 5x and a tip end side boom 5z are connected by an intermediate boom 5y.

An outline of the hydraulic circuit is shown in FIG. 3. The control valve 29 for the dozer cylinder and the control valve 3 for the bucket cylinder 7c are shown.
0, control valve 32 for left traveling motor 31, boom cylinder 5
c control valve 9, arm cylinder 6c control valve 10, right traveling motor 33 control valve 34, swing motor 45 control valve 3
5. A control valve 37 for the offset cylinder 36 and a control valve 38 for service are provided. Cross-operating operation levers 47 and 48 are provided on both sides of the seat 46 in the driving unit 44, respectively.
Is arranged. One is for boom-bucket,
The other is for arm-swirl. As shown in FIG. 5, potentiometers 49, 50, 51, 52 for detecting the operation amounts of the operating levers 47, 48 are connected to the control device 26 and electrically connected to the pilot valves 9a, 9b, 10a, 10b, 3 respectively.
It is a structure for operating 0a, 30b, 35a, 35b.
Then, for each control valve, an LS / S equipped with a variable displacement hydraulic pump 8 that is discharged at a pressure slightly higher than the load pressure, and an auto idle system (AI / AI) that is preferable in terms of noise and energy saving S) and are described below.

FIG. 4 shows a principle circuit diagram of a main part, which is an extracted portion of the boom cylinder 5c and the arm cylinder 6c surrounded by the phantom line in FIG.
9, the variable displacement hydraulic pump driven by 9
Is a flow rate adjusting mechanism for variably setting the amount of oil discharged per unit time of the hydraulic pump 8. The flow control mechanism 13 is provided with a horsepower control cylinder 13 </ b> A operated by the discharge pressure of the main pump 8.
And the flow control cylinder 13 driven by the regulating pump 18
B.

A pressure compensation type flow rate control valve 14 for the control cylinder 13 is also provided. 11 is for the boom and 12
Is each compensator (pressure compensation valve) for the arm,
Throttle valves 9 s and 10 s are provided in supply-side oil passages in the boom control valve 9 and the arm control valve 10. Each control valve 2 other than the control valves 9 and 10 for the boom and the arm is used.
The valve structures 9, 30, 32, 34, 35, 37, 38 (excluding the operation structure) are all basically the same as the control valves 9, 10 for the boom and the arm.

The compensators 11 and 12 are located on the lower side of the pressure oil supply to the supply side throttle valves 9s and 10s,
In addition, they are arranged on the upstream side of the pressure oil supply to the actuators 5c and 6c. And each compensator 1
The low pressure side oil passages 11t and 12t are provided on the lower side of the pressure oil supply for the actuators 1 and 12 and for communicating the pressure oil supply upper side portion for the actuators 5c and 6c and the spring side oil chambers of the compensators 11 and 12, respectively. There is.

Throttle valves 9s, which are on the good side of the pressure oil supply to the compensators 11 and 12, and also on the oil passages on the supply side.
The high-pressure side oil passage 1 that communicates the lower side of the pressure oil supply for 10 s with the non-spring side oil chamber of each of the compensators 11 and 12.
1k and 12k are provided. Each compensator 11,1
2, a constant pressure reducing valve provided with a compression spring 17 for biasing the flow path to the disconnection side, thereby forming an after-orifice type load sensing circuit.

There is provided a first low pressure side oil passage 14t which communicates the spring side oil chamber 14x of the flow rate control valve 14 and the pressure oil supply lower side portion for the respective supply side throttle valves 9s, 10s, and each low pressure side oil passage. The first low-pressure side oil passage 14t communicates with 11t and 12t. A dedicated connection oil passage 16 is provided between the second oil passage 15 communicating with the supply ports 9p and 10p of the control valves 9 and 10 and the oil chamber on the flow control valve 14 opposite to the spring-side oil chamber 14x.
Are in communication. The pressure applied to the adjusting cylinder 13 when the flow control valve 14 is switched is covered by the dedicated adjusting pump 18 which is driven by the engine together with the hydraulic pump 8. That is, the flow control valve that operates the adjusting cylinder 13 so as to maintain the pressure difference between the first oil passage 14t and the second oil passage 15 communicating with the supply ports 9p and 10p of the control valves 9 and 10 at a predetermined value. 14 and load control means A
Is configured.

Then, the first potentiometer 25 for electrically detecting the operation amount of the accelerator lever 24 for adjusting and setting the engine speed by artificial operation, and the geared motor 22 for driving and operating the governor lever 21 of the governor 20.
And an operation detecting means 23 for detecting whether or not a hydraulic actuator such as the boom cylinder 5c is operating,
When the hydraulic actuator is stopped, the engine speed is changed to the idling side, and when the hydraulic actuator is operated, the engine speed is adjusted to the set value by the accelerator lever 24.
5 is provided with an accelerator control means C that links the geared motor 22 with the geared motor 22.

That is, the second potentiometer 2 for feedback for detecting the operating position of the governor lever 21.
7, a geared motor 22, a pressure sensor 23 for detecting the pressure of the above-described first low pressure side oil passage (corresponding to the first oil passage) 14t,
Further, the control device 26 is provided with an accelerator control means C that links the first potentiometer 25.

That is, by operating the hand accelerator lever 24 at the idling position i, the engine speed in the working state (usually set to the full accelerator position m) is set, and if the working state, the setting is made. The engine speed is kept idling, and the engine speed is lowered to the idling state while the accelerator lever 24 is kept set to the position m when not working (no load). In this case, the pressure sensor 23 forms an operation detecting unit.

Further, the adjusting means B capable of changing and adjusting the throttle amounts of the throttle valves 9s and 10s is provided, and when the engine speed is increased, the driving speed of the hydraulic actuator such as the boom cylinder 5c becomes faster and the engine speed becomes lower. The control device 26 is provided with a speed control means E that links the second potentiometer 27 and the adjusting means B so that the driving speed of the hydraulic actuator becomes slower when the hydraulic actuator is driven.

The adjusting means B includes the compensators 11, 1
2 low pressure each low pressure oil passage 11t, 12t and 1st low pressure oil passage 14
t is connected via an electromagnetic high-speed response valve 28. The electromagnetic high-speed response valve 28 communicates the low pressure side oil passages 14t, 11t, 12t in the normal position b, and the low pressure side oil passages 11t, 12t in the high pressure position a and the high pressure second oil passage in the high pressure position a. The two-position switching valve structure is constructed so that the oil passage 15 is communicated with the oil passage 21a.

By operating the electromagnetic high-speed response valve 28, the hydraulic pressure acting on the low pressure side oil passages 11t, 12t of the compensators 11, 12 can be set to an intermediate value between the load pressures of the actuators 5c, 6c and the discharge pressures of the pumps. 1
Compensator 1 by the differential pressure maintaining action by 1 and 12
The supply pressure to the valves 1 and 12 is higher than when the electromagnetic high-speed response valve 28 is at the normal position b. Then, in order to keep the differential pressure between the first low-pressure side oil passage 14t and the discharge pressure of the hydraulic pump 18 constant, the differential pressure at the throttle valves 9s, 10s on the upstream side of the compensators 11, 12 is reduced. That is, control is performed so that the throttle amounts of the throttle valves 9s and 10s are reduced, that is, the opening degrees of the control valves 9 and 10 are reduced. As a result, the amount of oil supplied to the actuators 5c and 6c is reduced, and the driving speed is reduced. It becomes. This action is maintained even if the load changes due to the control structure based on the differential pressure between the load pressure and the pump differential pressure.

On the contrary, when the supply pressure to the compensators 11 and 12 is lowered, the differential pressure between the throttle valves 9s and 10s is increased, that is, the throttle amount of the throttle valves 9s and 10s is increased.
That is, the control valves 9 and 10 are controlled so as to increase their opening degrees, the amount of oil supplied to the actuators 5c and 6c increases, and the driving speed increases.

A second potentiometer 27 for detecting the number of revolutions of the engine 19, an electromagnetic high-speed response valve 28,
Setting device 3 that variably adjusts the duty ratio of intermittent operation time
9 and a switch 40 for switching between the automatic control mode and the manual control mode are connected to the control device 26, and the compensator 1
The partial pressures 1 and 12 are configured to be changed and set. That is, by changing the partial pressure, the throttle valves 9s, 1
The adjusting means B capable of changing and adjusting the opening degree of 0 s is configured. The adjusting means B intermittently energizes the electromagnetic high-speed response valve 28, which is urged to return to the high pressure position a, to the normal position b where it is connected to the high pressure oil passage which is the discharge oil passage of the hydraulic pump 8. It has the functions of intermittent operation and intermittent control that variably sets the intermittent time.

The operation of the speed control means E will be described. First, the changeover switch 40 is operated in the automatic control mode to intermittently energize the electromagnetic high-speed response valve 28.
It is linked so that the ratio of the energization time in one cycle of the intermittent time, that is, the duty ratio is reduced when the rotation speed of the engine 19 is low. Accordingly, if it is desired to reduce the turning speed during excavation work, the accelerator lever 24 can be operated to lower the engine speed, and conversely, to increase the drive speed, the engine speed can be increased. .

When it is desired to intentionally change the driving speed of the actuator, the changeover switch 40 is operated in the manual operation mode so that the second potentiometer 27 and the control device 2 can be operated.
Disconnect from 6. Then, the duty ratio is set by the setting device 3.
The state determined by 9 is set, and the supply pressure to the compensators 11 and 12 can be set to an arbitrary value between the load pressure of the actuators 5c and 6c and the pump discharge pressure by the manual operation of the setting device 39. 5c, 8
The drive speed of c can be adjusted independently of the engine speed.

As shown in FIGS. 1, 2 and 5, there is provided a bucket position detecting means D capable of detecting the position of the bucket 7 with respect to the turning center Q of the swivel base 2 so that the bucket 7 approaches the turning center Q. When the distance between the turning center Q and the bucket 7 (hereinafter, abbreviated as a turning-bar distance) reaches a predetermined distance during the movement to, until the second predetermined distance smaller than the predetermined distance is reached. When the swivel speed of the swivel base 2 is gradually reduced, and when the swivel bar interval reaches the second predetermined distance when the bucket 7 moves in a direction away from the swivel center Q, the swivel speed is increased to the speed before deceleration. There is provided acceleration / deceleration control means F which is controlled so that the absolute value of the acceleration at the time of increasing the speed becomes larger than the absolute value of the deceleration at the time of gradually decreasing the turning speed.

That is, at the pivotal connection point between the tip boom 5z and the arm 6, at the pivotal connection point between the base boom 5x and the intermediate boom 5y, and at the pivotal connection point of the base boom 5x to the swivel base 2, respectively. Since the potentiometers 41, 42, 43 are equipped and the respective elements of the excavation work device 3 such as the arm length and the moving distance of the bucket with respect to the offset angle to the left and right are stored in advance, the three potentiometers 41, 4 are provided.
The bucket 7 with respect to the turning center Q from the angle detection of 2, 43
The bucket position detecting means D for calculating and detecting the position of is provided. The positions of the bucket 7 are the arm 6 and the bucket 7.
Is obtained as the position of the bucket pin 7a connecting
The bucket position detecting means D functions to constantly calculate the distance on the horizontal plane with respect to the turning center Q of the bucket pin 7a as the turning bar interval.

The function of the acceleration / deceleration control means F will be described. The predetermined distance d1 and the second predetermined distance d2 are defined as shown in the backhoe plan view of FIG. That is, a predetermined distance d1 is set in a state of being a line extending in the left-right direction with respect to the swivel base 2 so as to substantially match the outer line of the front deceleration region B1.
Is set, and at a position near the rear limit position (storage position) s of the bucket 7 with respect to the swivel base 2,
The second predetermined distance d2 is also set as a line extending left and right with respect to the swivel base 2.

First, when the bucket pin 7a reaches the predetermined position d1 while the excavation work device 3 is driven to be folded and the bucket 7 is drawn closer to the swing center Q, the swivel base 2 is swung at that time. When it is being set, the turning speed is gradually reduced. Then, the bucket 7 is continuously pulled and the bucket pin 7a is in the second position.
The turning speed is gradually reduced until the predetermined distance d2 is reached, and if the second predetermined distance d2 or less is reached, the gradually decreased low turning speed is maintained. That is, in the relationship graph between the bucket position and the turning speed shown in FIG. 6, line (a) →
It changes so as to follow (b) → (c).

Next, when the excavation work device 3 is driven to extend and the bucket 7 is moved in the direction away from the turning limit Q from the rear limit position s, the bucket pin 7a reaches the second predetermined position d2. Then, when the swivel base 2 is swung at that time, a rapid increase in the turning speed is started. Then, the bucket pin 7a is at the predetermined position d.
When it reaches a speed return position d3 located between 1 and the second predetermined position d2, it returns to the high turning speed before deceleration, and is maintained at the original turning speed at a position farther than the speed returning position d3. The absolute value of the acceleration of the turning speed during the extension driving is larger than the absolute value of the deceleration during the folding driving, and is set so as to quickly return to the original turning speed. That is, in the relationship graph between the bucket position and the turning speed shown in FIG. 6, the line (c) →
Since it changes so as to follow (d) → (b), hysteresis is provided for deceleration and acceleration of the turning speed.

Note that A1, A2, B1, and B2 shown in FIG. 2 indicate the positions of the bucket pins 7a, respectively, where A1 is the front stop surface, A2 is the lateral stop surface, B1 is the front deceleration area, and B2 is the lateral deceleration area. That is, the respective stop surfaces A1 and A2 are lines that are automatically controlled to prevent further movement of the bucket 7 toward the cabin 44, and the deceleration areas B1 and B2 are the areas of the bucket 7 in this area. The moving speed is controlled to be accelerated or decelerated.
Further, C1 and C2 indicate loci in which the tip of the bucket 7 is closest to the cabin (driving section) 44 when the bucket pin 7a exists on the front and side stop surfaces A1 and A2, respectively. Since it is well known in Japanese Patent Application Laid-Open No. 4-333731, detailed description thereof will be omitted. However,
In the publication, the stop surface referred to in the present application is expressed as a "dangerous surface".

The deceleration of the excavation work device 3 in the deceleration areas B1 and B2 and the stop of the excavation work device 3 in the stop surfaces A1 and A2 are for boom, arm, and bucket, respectively.
And control valves 9, 10, 30, 35 for turning, pilot valves 9a, 9b, 10a, 10b, 30a, 30 for operating
b, 35a, 35b is a known technique (see Japanese Patent Laid-Open No. 4-333731), the acceleration / deceleration control means F, like the speed control means E, has a gain (differential pressure) of LS / S. ) The turning speed is changed by control.

That is, when the value detected by the bucket position detecting means D reaches the predetermined position d1 or the second predetermined position d2, the adjusting means B operates to reduce the opening of the swing control valve 35, and the swing motor (turning hydraulic pressure). An example of an actuator) 45 is linked so as to change the speed. Since this gain change control acts not only on the control valve 35 for turning but also on all control valves, when the turning speed is actually increased or decreased, the hydraulic actuators 5c, 6c of the excavation work device 3 are simultaneously operated. , 7c, 36 and the drive speeds of the traveling motors 31, 33 are also increased or decreased.

[Other Embodiment] The boom is not offset,
In addition, in the backhoe having a general structure provided with the swing cylinder, the bucket 7 has a turning center Q to some extent.
A structure may be adopted in which the turning speed is reduced when the vehicle approaches (at a predetermined position). And, as the deceleration operation structure when the bucket is below the predetermined position, the above-mentioned LS / S
In addition to changing the gain in step 1, means for forcibly operating the pilot valve may be used. Further, as shown by phantom lines in FIG. 2, the predetermined positions d1, d2, d3 may be defined as arc lines centering on the turning center Q.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a side view of a backhoe.

FIG. 2 is a plan view of a backhoe.

FIG. 3 is a schematic overall view of a hydraulic circuit.

FIG. 4 is a partial hydraulic circuit diagram showing the principle of load sensing with auto idle.

FIG. 5 is a control block diagram.

FIG. 6 is a diagram showing a relationship graph between bucket position and turning speed.

[Explanation of symbols]

 5c hydraulic actuator 7 bucket 8 hydraulic pump 9 control valve 9s throttle valve 9p pressure oil supply port 13 flow rate adjusting mechanism 14t first oil passage 15 second oil passage 31,33 traveling hydraulic actuator 45 turning hydraulic actuator A load control means B Adjusting means D Bucket position detecting means Q Turning center

Claims (5)

[Claims] 1. A bucket position detecting means (D) capable of detecting the position of a bucket (7) with respect to a turning center (Q) of a swivel base (2) is provided, and the turning center (Q) and the bucket (7) are connected to each other. A turning speed control device for a backhoe in which a turning hydraulic actuator (45) and the bucket position detecting means (D) are linked so that the turning speed of the turning base (2) is reduced when the distance becomes equal to or less than a predetermined distance. 2. The traveling hydraulic actuators (31), (33) and the bucket position detecting means (D) so as to reduce the traveling speed of the airframe when the distance becomes a predetermined distance or less.
The turning speed control device for the backhoe according to claim 1, wherein 3. A working hydraulic actuator (5c),
Variable displacement hydraulic pump (8) and throttle valve (9s) for pressure oil supply path to the hydraulic actuator (5c)
And a flow rate adjusting mechanism (1) for variably setting the discharge amount of the hydraulic pump (8) per unit time.
3), a first oil passage (14t) communicating with a lower side of the pressure oil supply to the throttle valve (9s), and a second oil passage communicating with a pressure oil supply port (9p) of the control valve (9). A load control means (A) for operating the flow rate adjusting mechanism (13) so as to maintain the differential pressure with the oil passage (15) at a predetermined value is provided, and the throttle amount of the throttle valve (9s) or the differential pressure is controlled. Adjustable adjusting means (B) and swivel center (Q) of swivel base (2)
And a bucket position detecting means (D) capable of detecting the position of the bucket (7) with respect to the bucket (7), and when the distance between the turning center (Q) and the bucket (7) becomes a predetermined distance or less, the turning base (2) turns. A backhoe turning speed control device in which the bucket position detecting means (D) and the adjusting means (B) are linked so that the speed is reduced. 4. The turning of the backhoe according to claim 1, wherein the turning speed of the turning base (2) is set to be gradually reduced when the distance becomes equal to or less than a predetermined distance. Speed control device. 5. When the distance reaches the predetermined distance when the bucket moves in a direction approaching the turning center (Q), until the second predetermined distance smaller than the predetermined distance is reached. When the turning speed of the swivel base (2) is gradually reduced and the distance reaches the second predetermined distance when the bucket (7) moves away from the swivel center (Q), the swivel base ( The acceleration is started to return the turning speed of 2) to the speed before deceleration, and the absolute value of the acceleration at the speed increase is controlled to be larger than the absolute value of the deceleration at the gradual decrease of the turning speed. The turning speed control device for a backhoe according to any one of claims 1 to 3, which is configured.