GB2243359A

GB2243359A - Backhoe

Info

Publication number: GB2243359A
Application number: GB9104823A
Authority: GB
Inventors: Keisuki Miura; Sakae Sugawara; Hitoo Nasu; Katsuhiko Yukawa
Original assignee: Kubota Corp
Current assignee: Kubota Corp
Priority date: 1990-04-11
Filing date: 1991-03-07
Publication date: 1991-10-30
Anticipated expiration: 2011-03-07
Also published as: GB9104824D0; DE4110978A1; DE4110991A1; GB9104823D0; DE4110959C2; GB2242886A; FR2660950B1; GB2243141B; FR2660949B1; FR2660948B1; GB9104827D0; FR2660950A1; DE4110959A1; GB2243141A; DE4110978C2; FR2660949A1; GB2242886B; GB2243359B; FR2660948A1; DE4110991C2

Abstract

A backhoe comprises a boom assembly connected to a swivel deck laterally of a driver's section. The boom assembly includes a boom connected to the swivel deck, a horizontal offset mechanism connected to the boom, a bucket arm connected to the offset mechanism, and a bucket connected to a forward end of the bucket arm. A plurality of angle sensors are provided to detect angular relations among the components of the boom assembly, and thus an overall posture of the assembly. Detection signals of the sensors are used to control the boom assembly. When the bucket is approaching the driver's section, the closer the bucket is, the more slowly the boom assembly is moved. The boom assembly is stopped upon entry of the bucket to a danger zone defined adjacent the driver's section (SL1, FL1). Preferably the deceleration rate is in inverse proportion of the distance of the bucket arm from and up to the front danger line and zero thereafter. <IMAGE>

Description

The described With operation unfolded, assembly rearwardly BACKHOE present

invention relates to a backhoe in the preamble of claim 1. this type of backhoe, typically, a is carried out with the backhoe and earth duQ and carried b-,,- the as digging assembly backhoe truck standing of the backhoe, for example. For this purpose, the swivel deck is turned after folding the backhoe assembly, i.e. after securing a space for turning the swivel deck. Particularly in a narrow site, the backhoe assembly is frequently folded and unfolded as above. When the backhoe assembly is folded for containment in a especially, is unloaded on the bed of a swivel deck region, the bucket moves close to the driver's section and puts the driver on the strain.. Thus, a backhoe has been proposed, as disclosed in the Japanese patent application laid open under No. 1989178621, to provide controls to prevent the bucket from approaching the driver's section as a safety measure.

In the known backhoe, a position of the bucket relative to the driver's section is computed on the basis of a swing angle of the boom with respect to the swivel deck, a swing angle of the arm with respect to the boom, and an amount of sideways movement of the bucket with respect to the proximal end of the boom.

When the bucket has entered a danger zone defined around the driver's section, the bucket is slowed down or stopped to avoid its abnormal approach to the driver's section.

With such a safety control, however, when the backhoe assembly is folded towards the driver's section for containment, the bucket often enters the danger inertial operation unloading a narrow position necessary inefficient.

zone as a result of an operating error or an overrun. Consequently, where a digging carried out forwardly of the backhoe and an operation rearwardly thereof are repeated in site, folding of the backhoe assembly to the adjacent the driver's section, which is to obtain a small turning radius, is very An object of the present invention is to provide a backhoe of the type noted hereinbefore, which allows the backhoe assembly to be folded for containment adjacent the driver's section with increased efficiency and positional precision.

The above object is fulfilled, according to the present invention, by a backhoe of the type described above and having the features set out in the characterizing portion of claim 1.

With this backhoe, when the bucket, i.e. the bucket arm is moving towards the driver's section, the closer the bucket or bucket arm is.to the driver's section, the more slowly the boom, arm cylinder and/or offset mechanism become(s). Because of this deceleration control, the bucket arm and the bucket attached to a forward end thereof also are slowed down, which facilitates accurate positional control. Even when the bucket enters the danger zone and a stop' command issues, the bucket may be stopped immediately owing to the slow moving speed. Of course, the deceleration function does riot operate if the bucket, though in the danger zone, is moving away from the driver's section. Consequently, the bucket may leave the danger zone quickly.

This allows an operation accompanying approach of the bucket to the driver's section to be carried out safely. There is a further advanta.

qe that the danger zone may be set to a minimal width to provide a relatively large working area.

In a preferred embodiment of the present invention, the backhoe assembly is movable to a contained position in a swivel deck region by and the bucket adjacent a side of the boom. This construction enables the backhoe to dig earth forwardly and unload it on a truck standing rearwardly even in a site offsetting the bucket arm relative to the boom folding the boom and the bucket arm to place providing little more space than for turrii-i the swivel deck. In this case also, high efficienly and precision are secured for folding of the backhoe assembly.

In order that the present invention may be more fully understood, an embodiment will be, described hereinafter with reference to the drawings. In the drawings:- Fig.

Fig.

Fig. assembly Fig 1 is a side view of the backhoe, 2 is a plan view of a backhoe assembly, 3 is a side view showing the backhoe in a contained position, 4 is a plan view showing the backhoe assembly in the contained position, Fig. 5 is a block diagram of a contr-ol system for the backhoe, Figs. 6 to 13 are flowcharts of control operations, and Figs. 14A and 14B are schematic views showing a definition of danger zones.

The backhoe shown in Fig. 1 comprises a crawler track frame 2 having a bulldozer blade 1, and a swivel deck 4 rotatably mounted on the track frame 2. The swivel deck 4 carries a driver's section 3, an engine E and a boom assembly 5.

The boom assembly 5 includes a boom 6 forming a basic component thereof. The boom 6 has an end pivotally supported at a position of the swivel deck 4 laterally of the driver's section 3, and is vertically swingable by a boom cylinder C1. As shown in Fig. 2, the boom 6 includes a proximal member 6a acting as a main stay, a distal member 6b and an offset -mechanism. The offset mechanism includes an intermediate member 6c connecting the distal member 6b to the proxi.mal member 6a. to be swingable about a vertical axis. More particularly, a link 7 extends parallel to the intermediate member 6c between the proximal member 6a and distal member 6b, link attaching arms proximal member 6a and Th e link attachin8 and is pivotally connected to 7a and 71) supported by the distal member 6b, respectively. arms 7a and 7b, link 7 and intermediate member 6c constitute a parallelogram link With this construction, an offset distal boom member 6b to make a offset mechanism.

cylinder C4 causes the substantially parallel movement in a transverse direction relative to the proximal boom member 6a. As a result, a bucket arm 8 connected to the distal boom member 6b makes a parallel movement, i. e. becomes offset, transversely of the proximal boom member 6a. The bucket arm 8 is vertically swingable relative to the proximal boom member 6a by an arm cylinder C2. The bucket arm 8 carries a bucket 9 attached to a distal end thereof to be vertically swingable bucket cylinder C3.

With this construction, the bucket arm bucket 9 may be offset laterally of the engage in a groove digging operation along an outer lateral edge of the track frame 2. The entire boom assembly 5 may be contained within a turning locus of the swivel deck 4 by outwardly offsetting the bucket arm 8, raising the boom 6, and folding the arm 8 and bucket 9. In this state, as shown in Fig. 3 and as schematically shown in Fig. 4, the boom 6, arm 8 and bucket 9 are retracted towards the swivel deck 4, with the bucket 9 lying laterally of the boom 6 opposite the driver's section 3. This state allows a turning movement in a narrow space, and is called herein a small turn containment state.

The boom assembly 5 and swivel deck by a control device 10 provided by a 8 or vehicle to 4 are controllable in the driver's section. The control device 10 includes a pair of right and left control levers 10a and 10b rockable crosswise, i.e. back and forth and sideways, and an offset lever 10c.

Fig. 5 shows a block diagram of a control system for the backhoe according to the present invention. As seen, the control system includes a first sensor S1 and a third sensor S3 which are potentiometers for detecting control positions of one of the control levers 10a longitudinally and transversely of the swivel deck 4, and a second sensor S2 and a fifth sensor S5 which are potentiometers for detecting control positions of the other control lever 10b longitudinally and transversely of the swivel deck 4. Control states of the offset lever 10c is detected by a fourth sensor S4. Detection signals from these sensors are input to a control unit 11 -10 essentially of a microcomputer.

The control system further includes a boom valve V1 connected to the boom cylinder Cl, an arm valve V2 connected to the arm cylinder C2, a bucket valve V3 connected to the bucket cylinder C3, an offset valve V4 connected to the offset cylinder C4, and a swivel v-alve V5 connected to a swivel motor M, ean-h of these valves being an electromagnetic proportional control valve. The control unit 11 controls valve drive circuits D1-D5 connected to the boom valve VI, arm valve V2, bucket valve V3, offset valve V4 and swivel valve V5, respectively. When the control lever 10a is manually operated longitudinally of the swivel deck 4, for example, the control unit 11 outputs a signal to the valve drive circuit D1 based on a detection result provided by the first sensor S1 and various control modes, thereby operating the boom valve V1. As a formed result, the boom cylinder Cl is operated, basically, in a direction and at a speed cor-respondiriV, to a control position of the control lever 10a. Similarly, when the control lever 10a is manually operated sideways, the control unit 11 outputs a signal to the valve drive circuit D3 based on a detection result provided by the third sensor S3 and various control modes, thereby operating the bucket valve V3. As a result, the bucket cylinder C3 is operated, basically, in a direction and at a speed corresponding to a control position of the control lever 10a. When the control lever 10b is manually operated longitudinally of the swivel deck 4, the control unit 11 outputs a signal to the valve drive circuit D2 based on a detection result provided by the second sensor S2 and various control modes, thereby operatinp the arm valve V1. As a result, the arm cylinder C2 is operated, basically, in a direction and at a speed corresponding to a control position of the control lever 10b. When the control lever 10b is manually operated sideways, the control unit 11 outputs a signal to the valve drive circuit D5 based on a detection result provided by the fifth sensor S5 and various control modes, thereby operating the swivel valve V5. As a result, the swivel motor M is operated in a direction and at a speed corresponding to a control position of the control lever 10b. An operation of the offset lever 10c is input to the control unit 11 in a similar way, and the control unit 11, in response to the input signal, switches the offset valve V4 through the valve control circuit D4 to operate the offset cylinder C4 in a desired manner. As will be described 'in detail later, the control unit 11 checks whether or not actions of the cylinders based on the operations of the various levers are desirable from the safety and functional points of view, for example. Undesirable control commands are cancelled or altered.

Fig 1 shows various sensors provi ded to input the posture of the boom assembly 5, i.e. positions of the members constituting the booTit assembly 5, to the control unit 11. Specifically, a boom an81e sensor P1 is mounted at a proximal end of the boom cylinder Cl for detecting a swing angle of the boom 6 with respect to the swivel deck 4. An arm angle sensor P2 is mounted at a distal end of the boom 6 for detecting a swing angle of the bucket arm 8 with respect to the boom 6. A bucket angle sensor P3 is mounted on a link 12 operatively connecting the bucket cylinder C3 to the bucket 9 for detecting a swing angle of the bucket 9 with respect to the arm 6, a swing angle of the link 12 with respect to the arm 6 being detected as a bucket angle. Further, an offset sensor P4 is mounted on the boom 6 for detecting a swing angle of the intermediate boom member 6c with respect to the proximal boom member 6a in order to obtain an offset amount including a direction of offset of the bucket 9 with respect to the proximal boom member 6a. These sensors preferably comprise rotary type potentiometers. As shown in Fig. 5, outputs of the sensors Pl- P4 are input to the control unit 11. As a result, the control unit 11 recognizes the posture of the boom assembly 5.

The control system further includes a danger avert mode switch S9, a fold mode switch S6, an offset return switch S7 and a levelling mode switch S8 acting as control mode switches for operation of the boom assembly 5 which are all connected to the control unit 11. As will be described in detail later, the danger avert mode is intended to avert such dangers as the bucket making an abnormal approach to the driver's section 3 as a result of flexion or offset control of the boom assembly 5. The danger avert mode normally is turned on. The fold mode is intended to automatically return the boom assembly 5 from a working position extending forwardly of the swivel deck 4 to the small turn containment state noted hereinbefore. The offset return means automatic reinstatement, which is effected when returning the boom assembly 5 from the small turn containment state to the working position, of the bucket 9 in an offset position in which the bucket 9 lay before the containment operation. The levelling mode is for flexing the boom 6 and arm 6 when automatically containing the boom assembly 5, to maintain an opening plane of the bucket 9 substantially level.

A sequence of controlling the backhoe, particularly the boom assembly, according to the present invention will be described next. The following description contains the terms "scooping direction" and "dumping direction" to define operating directions of the angle forming components of the boom assembly 5. The "scooping direction" means a in which the bucket is guided to break and pick up earth. The "dumping direction" means a direction in which the bucket is guided to throw out a load.

When the backhoe is started, the program shown in Fig. 6 is started for the control unit 11. After checking parameters and initializing variables, various processes are carried out in a ti-me- sharing mode. That is, various processes are carried out in the form of interrupt actions taking place at predetermined intervals of time. Such interrupt processes include a main process, a process of signal direction input from the potentiometers, a process of input from the various control mode switches, a display process for a control panel, and a process of output to the valve drivers. In the main process, amounts of operation of various determined according drive devices of the backhoe to the various control modes.

are In the sensor signal input process, signals from the potentiometers acting as the sensors are accepted and for use in the main process. In from the control mode switches, converted into forms the process of input signals from the switches for setting control modes are accepted and converted into the forms used in the main process and necessary preparations are made. When, for example setting of the fold mode switch is confirmed, an amount of offset detected at that time is stored in a predetermined RAM area. In the display process, all data displayed on the control panel provided in the driver's section are controlled. In the process of output to the valve drivers, control signals are applied to appropriate valve drivers in accordance with amounts of cylinder operation determined and stored in the main process.

The main process will particularly be described hereinafter.

Referring to Fig. 7, when the main process is started, a control mode prepared in the process of input from the control mode switches is accepted at step #10. Next, a data of input from a control lever or the like prepared in the sensor signal input process are accepted at step #15. An amount of valve data at step #20. The is written into a #25. Further, joint arm and bucket prepared in the sensor signal input process and representing the posture of the boom assembly are accepted at step #30. In the subsequent steps, various control modes are checked; step #40 checks whether the offset control mode is set or not and, if i executed to call a subroutine for t Similarly, steps #50, #60 and 70 check the levelling control mode, fold control mode and offset return control mode and, if these operation is computed from this result of this computation predetermined RAM area at step angle data of the boom, bucket t is, step #45 is lie offset control.

modes are set, correspondin8 subroutines are called at steps #55, #65 and #75.

Subsequently, a cushion control process and a danger avert process are carried out at steps #80 and #90. In the course of these control mode routines and processing routines, the amount of valve operation is renewed as necessary. The amount of valve operation written at this time forms a basis for producing a control signal for application to a valve driver in the valve driver output process which is a separate interrupt routine. In response to this signal. the valve driver applies an appropriate current to the associated valve, thereby ultimately- to drive the corresponding cylinder.

The subroutines called in the main process will be described next.

Fig. 8 shows a flowchart of the offset control. After the direction of offset is checked at step #110, a proper value is taken from an offset contro', table at step #120 in accordance with the data on the offset lever control stored in the predetermined Then an amount of control used in the RAM area. valve driver associated with the offset. cylinder is computed and written at step #130.

Fig. 9 shows a flowchart of t,li(-:! levelling control. Firstly, at steps #210, #220 and #230, actual bucket, bucket arm and boom angles are computed from the data prepared in the sensor signal process.

At step #240, a bucket angle relative to the vehicle body is derived from these angles, and a deviation: f from a reference angle for levelling the opening plane of the bucket is computed. An absolute value of this deviation is compared with an allowance value: dA at step #250. If the deviation is within a range of allowance, the bucket control is omitted (step #260).

Otherwise, a control gain corresponding to the detected bucket angle is determined at step #270. An amount of bucket control is derived from the control gain and deviation: f at step #280, and is written into a predetermined RAM area at step #290.

Fig. 10 shows a flowchart. of the containment fold control. In this routine, checking is made step #305 as to presence of a command for the boom or movement of the direction.

arm i n If such a command is present, jumps to step #395 for cancelling the immediately. This means stopping progress on a decision the fold control has manipulates a control actuate the bucket arm the answer is "NO" at step #30-5, the program moves to step #310 to set the amount of boom control to a maximum value in the upward direction, and the amount or at. lowering of the dumping the program fold control the fold control in that an operation traversin occurred when the operator lever to lower the boom in the dumping direction.

if of bucket arm control to a maximum value in the scooping direction. Next, a height of the bucket from the ground is computed at step #315. If the height exceeds 1m, steps #320 to #350 are executed to set an amount of offset control. If not, the offset control is dangerous and, therefore, an amount of offset control is not set for the fold control. In setting an amount of offset control, firstl-,, an offset angle is compared with a target value at step #320 to determine whether the offset control should be effected rightward or leftward. If the offset angle exceeds the target value, a rightward offset is required. Then, the amount of offset control is set to a maximum value rightward at step #325, and anoffset direction flag is set to right at step #330. If the offset angle is less than the target value, a leftward offset is required. Then, the amount of offset control is set to a maximum value leftward at step #340, and the offset direction flag is set to left at step #350.

Subsequently, step #-360 is executed to check if the boom is in position for containment, i.e. if the boom angle is at its maximum. If the answer is in the affirmative, the amount of boom control is set to zero at step #365. Similarly, step #31-0 is executed to check if the bucket arm is in position for i.e. if the bucket arm angle is at its the answer is in the affirmative the containment, maximum. if amount of arm control is set to zero at step #375.

Next, whether the offset control is completed or not is checked at step #380. The rightward offset control is completed if the offset angle is less than the target value. The leftward offset control is completed if the offset angle is greater than the target value. If the offset control is found completed, the amount of offset control is rewritten into zero at step #365. Then, at step #390, whether the boom assembly is in the contained position or not is determined by checking if the amount 'of offset of boom control and the amount of are all set to zero. If the boom assembly is in the contained position, step #395 is executed levelling control.

Fig. control. switch input control, the amount bucket arm control to cancel the fold control command and the control command started with the fold 11 shows a flowchart of the offset return In this routine, a change of the fold mode from OFF to ON is confirmed in the process of from the various control mode switches. Upon this confirmation, a detected offset value, i.e. an offset value of the boom assembly before containment, is read from the predetermined RAN area at step #410. This previous offset value read is compared with a currently detected offset value at step #420. If the bucket must be moved rightward to return to the previously offset position, the amount control is set to the maximum value rightward at step #430. If the bucket must be moved leftward, the amount of offset control is set to the maximum value -17-.

of offset i 1 leftward at step #440. The offset return control is completed when the detected offset value equals the previous offset value (step #440). Then the offset return control is cancelled at step #450.

Though not particularly described herein, it is possible to provide a plurality of areas for storing offset values at a folding time, and a switch for selecting one of these values, which is read at step #410. This will enable the bucket, after a folding operation, position. offset to be reinstated in a desired offset It is also possible to store not only the position or positions but the boom angle, arm angle and bucket angle. Then, the boom assembly may be reinstated in the posture that the boom assembly took prior to a folding operation.

Figs. 12A and 12B show a flowchart of the cushion control. Shocks may conveniently be damped by reducing piston speed the closer to stroke ends in driving the boom cylinder, arm cylinder and offset cylinder used for the boom assembly. The cushion control is intended primarily for controlling the respective cylinders such that the moving speed of the pistons are reduced in the vicinity of stroke ends.

The boom cylinder is checked first. If the boom cylinder is driven in a stroke end region and in a direction to raise the boom (steps #500 and #505), a distance to the stroke end is computed from a detected boom angle, and a predetermined optimal value for boom control is (step #510). the operating distance from thus derived derived from the result of computation This optimal value is determined so that speed is increased in proportion to the the stroke end, for example. The value is used in rewriting the amount of boom control at step #515. The bucket arm cylinder is checked next. If the bucket arib cylinder is driven in a stroke end region and in the scooping direction (steps #520 and #525), a distance to the stroke end is computed from a detected bucket arm angle, and a predetermined optimal value for bucket arm control in the scooping direction is derived from the result of computation (step #530). The value thus derived is used in rewriting the amount. of bucket arm C:ontrol at step #535. Then the bucket arm cylinder is checked with respect to the dumping direction. If the bucket arm cylinder is driven in a stroke end region and in the dumping direction (steps #540 and #545), a distance to the stroke end is computed from a detected bucket arm angle, and a predetermined optimal value for bucket arm control in the dumping direction is derived from the result of computation (step #550).

The value thus derived is used in rewriting the amount of bucket arm control at step #555. Similarly, steps #560 to #595 are executed to effect the cushion control of the offset cylinder in stroke end re,,ions for rightward offset movement and leftward offset movement, respectively. This control sequence corresponds to that of the arm cylinder, description is not repeated here.

Subsequently, a cushion control is for the offset cylinder C4. This control the movement of the offset cylinder C4 and its carried out decelerates adjacent a target position in order to stop the cylinder at the target position accurately. When the bucket is moved leftward by means of the offset. mechanism, the bucket, under the force of inertia or the like, could overrun the target position. In some cases, the bucket could contact the driver's section to present a serious danger. To avoid such a situation, the decelerating process is effected during leftward movement of the bucket.

The concept of danger zones defined around the driver's section will now be described with reference to Figs. 14A and 14B.

Fig. 14A shows the danger zones around the backhoe. A first front danger line FL1 is set forwardly of the driver's section, and a second front danger line FL2 is set forwardly of the first front danger line FL1. A first side danger line SL1 is set t to the righthand side of the driver 's section, and a second side danger line SL2 is set. outwardly of the first side danger line SL1. The danger zones defined by the front danger lines are intended to prevent thebucket front. lines are approaching from approaching the driver's section from the The danger zones defined by the side danger bucket from the ri8hthand side. Further, as shown in Fig. 14B, a limiting zone for the boom angle is additionally set in a space forwardly of the driver's section. Conditions are set to the upward movement of the boom w116n the boom lies in the angular range: Z formed by lines VL1 and VL2..

Reverting the cushion control, the sequence intended to prevent the the driver's section from beginning at step #600 is a decelerating process to avoid danger in controlling thc! offset mechanism. This operation is carried out in order to minimize the possibility of the offset cylinder C4 causing the bucket to move further leftward from a set. position during folding of the boom assembly.

First, checking is made at step #600 whether the offset mechanism is moving leftward or not. Only when the answer is in the affirmative, the program moves to step #610 to check if the fold control is in progress.

When the fold control is in progress, step #620 is executed to check if the bucket lies inwardly of the second side danger line SL2.

deviation from a target value Only if it does, a is derived from a current offset position and a predetermined offset target position, the latter being an offset position to which the boom assembly is folded, and the deviation is used as a parameter for determining an amount of deceleration offset control (step #630). The amount of offset control thus determined is used to rewrite the stored amount of offset control at step #640.

If step #610 finds that the fold control is off, step #650 is executed to check if the buckel lies inwardly of the second side danger line SL2 and the bucket arm lies inwardly of the second front danger line FL2. Only when they do, a de\-iation from a target value is derived as noted above, which is used as a parameter for determining an amount of deceleration offset control (step #630). The amount of offset control thus determined is used to rewrite the stored amount of offset control at step #640. if the above conditions are not met, the cushion control is terminated without rewriting the stored amount of offset control.

The danger avert control will be described next with reference to the flowchart of Fig. 13. This control is also effected in relation to thedanger 22- 1 zones shown in Fi8s. 14A and 14B. With the type of backhoe according to the present invention, an upward swing of the boom and a swing in the scooping direction of the bucket arm cause the bucket to move from front towards the driver's section, and an offset movement of the bucket involves movement of the bucket from a righthand side position towards the driver's section. The danger avert control, therefore, prohibits the upward swing of the boom and the swing in the scooping direction of the bucket arm in the front danger zone, and the leftward offset movement in the side danger zone. Further, to ensure the danger avert control, a outwardly of the second front danger line FL2 for slowing down operation of the corresponding in accordance with distances of the boom and the danger zone.

deceleration zone i S def ined cyl inders arm to In the danger avert control, when commands for operating the boom assembly are given by manual operation of the control levers 10a and 10b and offset lever 10c, posture of the boom assembly, i.e. positions and moving directions of the components of the boom assembly, are computed from detection data regarding the boom angle, arm angle and offset amount then available. When these positions and directions are problematic, amounts of operation of corresponding cylinders are reduced or, if necessary, rewritten into zero. For example, if the bucket lies inwardly of the second side danger line SL2 and the arm inwardly of the first front danger line FL1, the leftward offset movement is cancelled. If the bucket lies inwardly of the first side danger line SL1 and the arm inwardly of the second front danger line FL2, the swing of the arm in the scooping direction is cancelled. If the bucket lies inwardly of the first side danger line SL1, the arm inwardly of the second front danger line FL2, and the boom angle within the angular range between the lines VL1 and VL2, the upward swing of the boom also is cancelled. If the bucket lies inwardly of the second side danger line SL2 and the arm inwardly of the second front danger line FL2, whether the boom and bucket lie in the deceleration zone, i.e. the distance to the danger zone, is computed and a decelerating process is carried out accordingly.

Specifically, in the routine shown in Fig. 13, checking is made at step #700 whether the bucket lies inwardly of the second side danger line SL2. If not, this routine is terminated since the danger avert control is not required. If the bucket lies inwardly of the second side danger line SL2, step #705 is executed to check whether the bucket arm lies inwardly of the second front danger line FL2. If the bucket arm lies outwardly of the second front danger line FL2, the concept of the deceleration zone noted hereinbefore is introduced. Thus, at step #710, the amount of bucket arm control is derived, as necessary, from the distance, with the current boom angle, of the bucket arm to the danger zone, and the amount of boom control from the distance, with the current bucket arm angle, of the boom to the danger zone. At step #715, the respective amounts of control are rewritten into the values determined above. If the bucket arm lies FL2, are inwardly of the second front danger line operations of the bucket, bucket arm and boom cancelled in the following sequence, as necessary, depending on the positions thereof.

First, if the bucket arm lies inwardly of first front danger line FL1 (step #7220) and the the leftward offset control is in progress (step #725), into zero (steps #730 and #735). Thus, the offset control set before commencement of this routine is cancelled.

Next, if the bucket lies inwardly of the first side danger line SL1 (step #740) and the bucket arm is moving in the scooping direction (step #745), the amount of arm control is rewritten into zero (steps #750 and #755). Thus, the bucket arm control set before commencement of this routine is cancelled.

the amount of offset control i s rewritten Finally, if the boom angle is within tl-ie angular range defined by lines VL5 and VL6 (step #760), the bucket lies inwardly of the first side danger line SM (step #765) and the boom is being raised (step #770), the amount of boom control is rewritten into zero (steps #775 and #7380. Thus, the bucket arm control set before commencement of this routine is cancelled.

The above process cancels the control resulting in the boom assembly, particularly the bucket, approaching the driver's section to a dangerous extent.

In this way, the amount of control initially set through the control lever 10a or 10b or offset lever 10c is reduced or cancelled, as necessary, through the routine of cushion control or danger avert control. The resulting final value is used in the output thereby to actuate the cylinders. With such a cylinder routine. Depending on the boom assembly construction and cylinder strokes, the amount of deceleration control computed in the danger avert control routine could exceed the amount of control computed in the preceding cushion control routine, for example. To avoid such an inconvenience, a condition may be set to data process noted hereinbefore valve drivers and hence the method, priority is given to the amount of control derived from a subsequent processing 1 rewriting so that a value is not replaceable by a greater value.

Claims

We claim:

1. A backhoe comprising; a swivel deck, a driver's section mounted on said swivel deck, a backhoe assembly provided in a region laterally of said driver's section, said backhoe assembly including a boom vertically swingably connected to said swivel deck, an offset mechanism connected to said boom for horizontal offset movement relative to said boom, a bucket arm vertically swingably connected to said offset mechanism, and a bucket vertically swingably connected to a forward end of saidbucket.

arm, backhoe assembly drive means for dri-ine, the components of said backhoe assembly, posture detecting means for detecting posture of said backhoe assembly, said posture detecting means including a boom angle sensor for detecting a swing angle of said boom, an offset sensor for detecting an offset amount of said offset mechanism transversely of said bucket arm a bucket arm angle sensor for detecting a bucket angle said bucket, p swing angle of said bucket arm, and a sensor for detecting a swing angle of operator means for inputting amounts of operation of the components of said backhoe assembly, and control means responsive to said operator means for controlling said backhoe assembly through said backhoe assembly drive means, said control means being operable to compute positions of said boom, said bucket arm and said bucket relative to said driver's section from a signal from said boom angle sensor, a signal from said offset sensor, a signal from said bucket arm angle sensor and a signal front said bucket angle sensor, characterized in that said control means has (1) an inhibit function to inhibit movement of said boom and said bucket arm in a scooping direction when said bucket lies inwardly of a side danger line defined laterally of said driver's section on the same side on which said backhoe assembly is located, and said arm lies inward13, of a front dar,Eei- line defined forwardly of said driver's section, and (2) a delay function to move said boom and said bucket arm in said scooping direction at a speed computed by using as a parameter a distance of said bucket arm from said front danger line, to decelerate said bucket approaching said driver's section.

2. A backhoe as claimed in claim 1, characterized that the delay function of said control means in i S effected with a deceleration rate substantially in inverse proportion to said distance of said bucket arm from said front danger line when said distance is up to a predetermined value, and with zero deceleration rate when said distance exceeds said predetermined value.

3. A backhoe as claimed in claim 1 or 2, characterized in that said backhoe assembly is movable to a contained position in a swivel deck region by offsetting said bucket arm relative to said boom and folding said boom and said bucket, arm to place said bucket adjacent a side of said boom.

Published 1991 at The Patent Office, Concept House. Cardiff Road. Newport. Gwent NP9 1RH. Further copies may be obtained from Sales Branch. Unit 6. Nine Mile Point. CwmfeWffach, Cross Keys. Newport Npl 7HZ. Printed by Multiplex techniques ltd, St Mary Cray, Kent.

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