GB2243141A

GB2243141A - Backhoe

Info

Publication number: GB2243141A
Application number: GB9104827A
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: 1991-10-23
Anticipated expiration: 2011-03-07
Also published as: DE4110959A1; GB2242886B; GB2243141B; GB9104827D0; GB2242886A; DE4110978C2; GB9104824D0; GB2243359A; FR2660948B1; FR2660949A1; GB2243359B; DE4110959C2; DE4110991A1; FR2660949B1; DE4110991C2; FR2660948A1; FR2660950B1; DE4110978A1; GB9104823D0; FR2660950A1

Abstract

A backhoe (3) 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 fold the boom assembly in a way to avoid its collision with the driver's section and to guide the assembly efficiently to a contained position within a swivel deck region. The control operates to inhibit movement of the bucket, boom and offset if (i) the bucket lies inwardly of a side danger line SL2 and the bucket arm lies inwardly of a front danger line FL1, (ii) to prevent scooping if the bucket lies inwardly of SL1 and the bucket arm is inwardly of FL2 and iii) prevent upward boom movement when the boom is inwardly of SL1, the arm is inwardly of FL2 and the bucket is forward of a drivers section. <IMAGE>

Description

--- -.C - BACKHOE The present invention relates to a backhoe as described

in the preamble of claim 1.

With this type of backhoe, typically, a digging operation is carried out with the backhoe assembly unfolded, and earth dug and carried by the backhoe assembly is unloaded on the bed of a truck standing rearwardly 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 swivel deck region, especially, the bucket moves close to the driver's section and puts the driver on the strain. Thus, a been proposed, as disclosed in the Japanese patent application laid open under No. 1989178621, to provide controls to prevent the bucket from approachinp the dri-,-r-r's se-tion as a safe±-- --sure.

In the known backhoe, a position of the bucket relative to the driver's section is detected 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.

backhoe has n 4 1 is 2, The result of this detection is used to determine whether or not the bucket has entered a danger zone DZ, as shown in Fig. 1.6, which is defined forwardly of the driver's section 203. When the bucket has entered the danger zone DZ, an upward swing of the boom, a scooping action of the arm and a sideways displacement of the bucket are automatically disabled, thereby avoiding the danger of the bucket encroaching on the driver's section. That is, when the bucket is offset to a position forwardly of the driver's section to engage in an operation, or when the backhoe assembly with the bucket in an offset position is folded towards the driver's section for containment, the bucket may enter the danger zone DZ by an operating error of the boom cylinder, arm cylinder or offset cylinder, or as a result of an inertial overrun due to the weight of the backhoe assembly. Then, only a downward of the bG.u. and' an. act.cn oil the bucket arm are allowed to prevent the bucket from making a further 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 and the bucket enters the danger zone DZ as a result of an operating error or an inertial overrun, it is necessary to return the bucket 209 from an entry position Pa to a safety position Pb 1 - 1 1 forwardly and outwardly of the danger zone DZ, thereby to cancel the disablement of sideways displacement resulting from the entry of the bucket 209 to the danger zone DZ. Thereafter the bucket 209 is moved sideways from the safety position Pb to an offset position PX for containment which is displaced to one side of the swivel deck. From this offset position PX the bucket must be drawn towards the swivel deck and to a small-turn, contained position PC to allow the swivel deck to turn in a minimum space. That is, the bucket 209 having entered the danger zone DZ must be returned from the entry position Pa to the safety so that the bucket becomes sideways displaceable. Consequently, the operation is inefficient when the backhoe assembly with the bucket in an offset position is folded for containment.

An object of the present invention is to provide a backhoe of the type noted hereinbefore, which allows the backhoe assembly to be efficiently folded for containment, and which has a control system for effecting controls therefor in a simple manner.

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

With this backhoe, movement of the bucket arm in a scooping direction is inhibited when the bucket lying inwardly of the first side danger line and moving toward the driver's section crosses the second front danger line. If, in addition, the boom lies within a danger swing angle range, upward movement of the boom is also inhibited. That is, upward movement of the boom and scooping movement of the arm are inhibited when the bucket approaches the driver's section from front and the bucket arm, and therefore the bucket, enter a danger zone defined forwardly of the driver's section. Consequently, the bucket is prevented from further approaching the driver's section by the movement of the boom and arm. At this time, the bucket remains allowed to move transversely by action of the offset mechanism.

Fig. 15, the bucket may be moved position Pa sideways to an offset.

Thus, as shown in from a stopping position PX for containment without moving forwardly away from the driver's section out of the danger zone.

P 1 uirther, when the bucket 2f the second side danger line SL2 and the arm lies inwardly of the first front danger line FL1, the bucket is regarded as having entered the danE;er zone and, therefore, movement of the offset mechanism towards the driver's section, namely, leftward movement of the bucket, is inhibited. This prevents the bucket from approaching the driver's section to an abnormal extent from front and side. According to such danger avert control, the backhoe assembly is moved smoothly from an unfolded position to a folded position with the bucket contained adjacent the boom while avoiding excessive access of the bucket to the driver's section. This feature improves efficiency loading/unloading operation accompanying folding and unfolding of the backhoe assembly.

In a preferred embodiment of the present invention a corresponding component of the backhoe assembly is controllable by an amount resulting from a value set through the operator means, the amount of control of the corresponding component being thereafter cancelled when an inhibit command is output for the corresponding component. That is, a control amount is first prepared by setting made through the operator means, and thereafter this control amount is renewed by a different control condition higher in the order of priority. The control sequence i s -er. simple even if there are many control conditions, which facilitates maintenance and revision.

In a further embodiment of the invention, the backhoe assembly is movable to a contained position in a swivel deck region by offsetting the bucket arm relative to the boom and folding the boom and the of the repeated bucket arm to place 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 providing little more space than for turning the swivel deck.

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.

assembly Fig assembly Fig.

the backhoe, Figs.

operations, Figs. 14A and 14B are sche-r,=-ti-,-- sh-wing a definition of danger zones, Fig. 15 is a schematic view showing an example of danger avert control- according to the present invention, and Fig. 16 is a schematic view showing an example of danger avert control according to the p-rior art.

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 in the contained position, is a block diagram of a control system for 6 to 13 are flowcharts of control X 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 21- 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 G, 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 Cl. 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 proximal member 6a to be swinsable 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, and is pivotally connected to link attaching arms 7a and 7b supported by the proxiial member 6a and distal ui,, The link attaching arms 7a. and 7b, link 7 and intermediate member 6c constitute a parallelogram link offset mechanism. With this construction, an offset cylinder C4 causes the distal boom member 6b to make a substantially parallel movement in a transverse direction relative to the proximal booir, member 6a. As L 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 by a bucket cylinder C3.

With this construction, the bucket arm 8 bucket 9 may be offset laterally of the vehicle or to' 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 b, ,.:cket 9 lying laterally --f the hccm 6 c,17r --- 3±-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 4 are controllable by a control device 10 provided in the driver's section. The control device 10 includes a pair of ri2ht and left control levers 10a and 10b 1 9 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 sensor control deck 4, and a second sensor S2 and S5 which are potentiometers a f if th for detecting" 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 formed 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 buc.KeTvalve V3 connected to the bucket cylinder C3, an offset val-,,-e V4 connected to the offset cylinder C4, and a swivel valve V5 connected to a swivel motor M, each of these,.-alves being an electromagnetic proportional control valve. The control unit 11 controls valve drive circuits D1D5 connected to the boom \,alve VI, arm valve V2, bucket valve V3, offset valve V4 and swivel -g- valve V5, respectively. When the control lever 10a is manually operated lonsitudinall, 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 result, the boom cylinder Cl is operated, basically, in a direction and at a speed corresponding to a control position of the control lever 10a. Similarly, operated to the 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 x-alve drive circuit D2 based on a detection result provided by the second sensor S2 and various control modes, thereby operating 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, when the control lever 10a is manuallsideways, the control unit 11 outputs a signal valve drive circuit D3 based on a detection 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 vals7e control circuit D4 to operate the offset c-,,- linder C4 in a desired manner.

later, the control As will be described in detail 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 provided to input the posture of the boom assembly 5, i.e. positions of the members constitutinE the boom assembl,,, " 5. to the control unit 11. Specifically, a boom angle 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 k 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 8, a swing angle of the link 12 with respect to the arm 8 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 PI-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 moae swiT-cr, So 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 t 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

Lainment operation. The levelling cont flexing the boom 6 and arm 8 when the mode is for 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 present invention will following description direction" directions of the angle assembly 5. The "scooping direction" means a direction 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 Fi8. 6 is started for the control unit 11. After assembly, according to the be described next. The contains the terms "scooping and "dumping direction" to define operating C forming components of the boom checking parameters and initializing variables, various processes are carried out in a time-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 input from the potentiometers, a process of input from the various control mode switches, a display process and a process of output to the of for a control panel valve drivers. In operation of various determined according the sensor signal the main process, amounts drive devices of the backhoe to the various control modes. input process, signals from -he sensors are accepted potentiometers acting as -11 are In the and converted into forms for use in the main process. In the process of input from the control mode switches, 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 provided in the process signals are data displayed on the control panel the driver's section are controlled. In of output to the valve drivers, control applied to appropriate valve drivers in i 1 1 1 t accordance with amounts of cylinder operation determined and stored in the main process.

The main process will particularly, be hereinafter.

described ReferrinR 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 or the like prepared in the sensor signal process are accepted at step #15. An amount of operation is computed from this data at step:!20 result of predetermined angle data of in the sensor lever input valve The this computation is written into a RAM area at step Further, joint the boom, bucket arm and bucket prepared signal input process and representing the posture of the boom assembly are accepted at step -30. In the subsequent steps, various control modes k, are checked; step -'40 checks whether the offset control mode is set or not and, if it is, step =45 is executed to call a subroutine for the offset control. Similarly, steps #50, #60 and 970 check the levelling control mode, fold control mode and offset return control mode and, if these modes are set, corresponding 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 control table at step:t1220 in accordance with the data on the offset lever control stored in the predetermined RAM area. Then an amount of control used in the valve driver associated with the effset cylinder i,:z comp-.L:ted and written at step #130.

Fig. 9 shows a flowchart of the levelling control. Firstly, at steps #2110, t!220 and #230, actual bucket, bucket arm and boom angles are computed from the data prepared in the sensor signal process. At step 2240, a bucket angle relative to the vehicle 16- S 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 or fold control. In this routine, checking is made at step #305 as to presence of a command for lowering of the boom or movement of the arm in the dumping the cancelling the fold stopping the fold control in that an operation traversing occurred when the cr.eratolever to lower the boom or actuate the bucket arm in the dumping direction. if the answer is "NW at step #305, the program moves to step #310 to set.the amount of boom control to a maximum value in the upward direction, and the amount of bucket arm control to a m a x i iri u u, va 1 u e in the direction. If such a command is present, jumps to step t395 for immediately. This means progress on a decision the fold control has manipulates a control program control A 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, control is not set an amount of offset is compared with determine whether effected rightward exceeds the target therefore, an amount of offset for the fold control. In setting control, firstly, an offset angle a target value at step #320 to the offset control should be or leftward. If the offset angle value, a rightward offset is required. Then, the amount of offset control is set to a maximum value rightward at step #-325, and an offset direction flag is set to rieh+ at Step;=330. If the offset angle is less than the target value, leftward offset is required. Then, the amount of offset control is set to a maximum value leftward at step TC340, and the offset direction flag is set to left at step 1C350.

Subsequently, step i#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 370 is executed to check if the bucket arm is in position for containment, i.e. if the bucket arm anEle is at its j 1 maximum. If the answer is in the affirmative, the 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;t3'10, whether is in the contained position or not checking if the amount of offset control, the amount of boom control and the amount of bucket arm control are all set to zero. If the boom assembly is in the contained position, step tt395 is executed levelling control.

Fig. control the boom assembly is determined by 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 switch from OFF to ON is confirmed in the process of input 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 RAM area at step #410. This previous offset value read is compared with a a t currently detected offset value at step 1-420. If the bucket must be moved rightward to return to the previously offset position, the amount of offset 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 leftward at step #-440. The offset return control is completed when the detected offset value equals the previous offset value (step 1-440). Then the offsetreturn control is cancelled at step 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 operation, to be reinstated in a desired offset position. It is also possible to store not only the offset position or positions but the boom anEle, arm angle and bucket angle. Then, the boom assembly may be reinstated in the posture that -Lie abseiizb-L, took prior Fi8s.

control. redu c i rig driving cylinder to a folding operation.

12A and 12B show a flowchart of the cushion chocks may conveniently be damped by piston speed the closer to stroke ends in the boom cylinder, arm cylinder and offset 1 t 1 y.

ised for Lhe boom assem. The cushion -20-.

If 1 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 -P-500 and c-505), a distance to the stroke end is computed from a detected boom angle, and a predetermined optimal value for boom control is derived from the result of computation (step:c510). This optimal value is determined so that the operating speed is increased in proportion to the distance from the stroke end, for example. The value thus derived is used in rewriting the amount of boom control at step #515. The bucket arm cylinder is checked next. If the bucket arm 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 scoopinp direction is deri-,-pd frem, the reslilt of computation (step #530). The value thus derived is used in rewriting the amount of bucket arm control 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 dunipine direction (steps;:540 and a 4 i 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 regions for rightward offset movement and leftward offset.

movement, respectively. This corresponds to that of the arm description is not repeated here.

Subsequently, a cushion control is carried out for the offset cylinder C4. This control decelerates the movement of the offset cylinder C4 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 tarEet position. T + P p - - 1. 1, r_ 2- o L' contact the driver's section to present a serious danger. To avoid such a situation,the decelerating process is effected during leftward mo, ,-eiLent of the bucket.

The dri ver's control sequence cylinder, and its concept of danger zones defined around the secticr., will now be descril-le-- reference to Fi8s. 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 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 the bucket from approaching the driver's section from the front. The danger zones defined by the side danger lines are intended to prevent the bucket from approaching the driver's section from the righthand 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 when the boom lies in the angular range: Z formed by lines V1,1 and VL2.

Reverting the cushion control, the sequence beginning at step #600 is a decelerating process to avoid danger in controlling the 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.

1 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 insardly of the second side danger line SL2. Only if it does, a deviation from a target value 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 #'6 4 0.

If step #610 finds that the fold control is off, step #650 is executed to check if the bucket 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 deviation from 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 t640. if a i i 1 i i t z 1 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 the danger zones shown in Figs. 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 deceleration zone is defined outwardly of the second front danger line FL2 for slowing down operation of the corresponding cylinders in accordance with distances of the boom and arm to the danger zone.

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 FL.24-, 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 1 1 i 1 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 cheek 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 deri-, ,-ed, 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 the values determined above. If the bucket arm inwardly of the second front danger line operations of the bucket, bucket arm and cancelled in the following sequence, as depending on the positions thereof.

into lies FL2, boom are necessary, First, if the bucket arm lies inwardly of the 720) and the first front danger line FL1 (step C leftward offset control is in progress (step #725), the amount of offset control is rewritten 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.

Finally, if the boom angle is within the angular range defined by lines VL5 and VL6 (step;c760), the bucket lies inwardly of the first side danger line SM (step "-765) and the boom is being raised (step;:r770), 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 cancelle,l, as necessary, throuph the routine of cushion control or danger avert control. The resulting final value is used in the output process noted hereinbefore, thereby to actuate the valve drivers and hence the cylinders. With such a method, priority is given to the amount of cylinder control derived from a subsequent processing routine.

1 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 rewriting so that a value is not replaceable by a greater value.

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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 said bucket arm, backhoe assembly drive means for driving 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 offset amount said bucket detecting a bucket angle said bucket, operator boom, an offset sens-- for de+ecting an of said offset mechanism transversely of arm, a bucket arm angle sensor for swing angle of said bucket arn, and a sensor for detecting a swing angle of means for inputtine- aTr..,-.),-,nts ef o-Peration 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 from said bucke t angle sensor, characterized in that said control means is operable (1) to inhibit movement of said offset mechanism towards said driver's section when said bucket lies inwardly of a second side danger line SL2 defined laterally of said driver's section on the same side on which said backhoe assembly is located, and said arm lies inwardly of a first front danger line FL1 defined forwardly of said driver's section, (2) to inhibit movement of said bucket arm in a scooping direction when said bucket lies inwardly of a first side danger line SL1 defined inwardly of said second side danger line SL2, and said bucket arm lies inwardly of a second front danger line FL2 defined outwardly of said first front danger line FL1, and (3) to inhibit upward no\-ement of said boom when said boom lies inwardly of said side danger line SL1, said bucket arm lies inwardly of said second front danger line FL2, and said boom lies within a danger swing angle range placing said bucket forwardly of said driver's section.

2. A backhoe as claimed in claim 1, characterized in that a corresponding component of said backhoe assembly is controllable by an amount resulting from a value set through said operator means, the amount of control of said corresponding component being thereafter cancelled when an inhibit command is output for said corresponding component.

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 nucKet arm to place said bucket adjacent a side of said boom.

Published 1991 at The Patent Office. Concept House. Cardiff Road. Newport. Gwent NP9 I RH. Further copies may be obtained from Sales Branch. Unit 6. Nine Mile Point. Cwmfelinfach. Cross Keys. Newport. NPI 7RZ. Printed by Multiplex techniques lid, St Mary Crky. Kent.

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