JPH0689553B2 - Automatic excavator for loading machines - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a driver's technique in a loading machine such as a wheel loader, a pay loader, or a tractor shovel by controlling a work machine actuator according to a load by a microcomputer. The present invention relates to an automatic excavation device for a loading machine, which is capable of performing efficient excavation work independent of the above.

[Conventional technology]

Loading machines such as wheel loaders, pay loaders or tractor shovels that have booms and buckets as work machine actuators are compact, have a small turning space, and have a low purchase price. It is used in a wide range of fields such as work.

In this type of loading machine, the boom cylinder rotates the boom up and down, and the bucket cylinder causes the bucket to perform tilting and dumping operations. Perform excavation and loading work.

[Problems to be solved by the invention]

By the way, a tandem circuit with a bucket priority is usually used for the hydraulic circuit of such a loading machine, and the switching valves for driving the boom cylinder and the bucket cylinder are on / off controlled with a fixed flow rate. It is not possible to operate the buckets at the same time, and it takes extremely advanced skill to switch each work implement actuator well and perform efficient excavation.
When the bucket is pushed too much in the horizontal direction, the vertical resistance becomes excessive and the rear part of the vehicle rises, the bucket rises too quickly and the excavated soil volume becomes insufficient, or the load becomes excessive and the tire slips. There is a problem that work efficiency greatly changes depending on the driving technique.

The present invention has been made in view of the above circumstances, and in a loading machine equipped with a hydraulic circuit that is a mainstream at present and has a fixed flow rate and only one of the actuators can be operated independently, it is possible to operate the loading machine without changing its configuration. It is an object of the present invention to provide an automatic excavating device for a loading machine that can efficiently excavate a predetermined amount of soil efficiently regardless of the skill of the operator.

[Means for solving problems]

In order to solve such a problem, according to the present invention, means for sequentially calculating a horizontal component and a vertical component of excavation resistance applied to a bucket and a first set value, an upper limit set value and a lower limit set value for the horizontal excavation resistance are provided. And set
Setting means for setting a set value relating to the vertical excavation resistance, and the calculated horizontal excavation resistance being larger than a first set value and the calculated vertical excavation resistance being smaller than a set value of the same vertical excavation resistance. Performs alternating switching control of the tilt movement of the bucket and the raising rotation of the boom so that the horizontal excavation resistance is reciprocated between the upper limit set value and the lower limit set value, and the calculated vertical excavation resistance is the same vertical excavation resistance. In order to perform tilting of the bucket until the predetermined excavation is completed after the resistance becomes larger than the set value, a switching control means for switching the work machine valves for respectively driving the boom and the bucket is provided. To

[Action]

According to such a configuration, according to the horizontal excavation resistance value, the intrusive travel → the intrusive travel / bucket tilt → the intrusive travel / boom rise → the intrusive travel / bucket tilt → the intensible travel / boom rise
The horizontal resistance reciprocates between the upper limit setting value and the lower limit setting value as a result of the cycle operation, and then the tilting motion of the bucket is reached at the end of the excavation after the vertical excavation resistance value becomes larger than the predetermined setting value. Will be held until.

〔Example〕

Figure 2 is shows an exemplary external configuration of a wheel loader to apply this invention, the wheel loader, the bucket angle sensor 2 for detecting the rotational angle theta ₁ of the bucket 1, the rotation angle theta ₂ of the boom 3 Boom angle sensor 4 for detecting the pressure, hydraulic pressure sensor 6 for detecting the hydraulic pressure Pa of the pressure oil supplied to boom cylinder 5 (not shown in FIG. 2), bucket cylinder 7
Oil pressure sensor 8 for detecting the oil pressure Pb of the pressure oil supplied to
(Not shown in the figure) is provided.

The detection values θ ₁ , θ ₂ , Pa and Pb of the bucket angle sensor 2, the boom angle sensor 4, the hydraulic pressure sensors 6 and 8 are the _first values.
Input to the microcomputer 10 as shown in the figure.
In the microcomputer 10, the horizontal component Rh and the vertical component Rv of the excavation resistance applied to the bucket 1 during excavation are sequentially calculated using these detected values, and in the automatic excavation mode, the hydraulic circuit 20 is based on these calculated values Rh and Rv. Drive control.

This hydraulic circuit 20 includes a boom control valve 21 that drives the boom cylinder 5, a bucket control valve 22 that drives the bucket cylinder 7, a tank 23, a work machine pump 24, a pilot operate control (POC) pump 25, and a boom control valve 21. The switching signal S ₁ from the microcomputer 10 is added to the tandem circuit configuration of the normal ON / OFF control type, which is composed of the lift pilot valve 26 for switching control and the tilt pilot valve 27 for switching control of the bucket control valve 22. And S ₂
The switching valves 30 and 40, which are activated respectively, are added. The switching valve 30 is arranged in the pilot line from the lift pilot valve 26 to the upper (agewa) lift spool 28 of the boom control valve 21, and the switching signal S ₁
Is not input, the pilot valve 26 and the upper lift spool 28 are connected, but when the switching signal S ₁ is input,
The POC pump 25 is directly connected to the upper lift spool 28. The switching valve 40 is disposed in the pilot line from the tilt pilot valve 27 to the tilt side dump spool 29 of the bucket control valve 22, and when the switching signal S ₂ is not input, the pilot pilot valve 27 and the tilt side dump spool 29 are provided. , But when the switching signal S ₂ is input, the POC pump 2
Directly connect 5 to the tilt side tamp spool 29. These switching signals S ₁ and S ₂ are input from the microcomputer 10 when the automatic excavation mode is designated by turning on the switch 11.

Here, before describing the automatic excavation operation according to the configuration of the embodiment, an example of a method of deriving the horizontal resistance Ph and the vertical resistance Rv will be described with reference to FIGS. 3 and 4.

In this method, as input information, the bucket rotation angle θ ₁ ,
Boom rotation angle θ ₂ , hydraulic pressure Pa of hydraulic oil supplied to boom cylinder 5, and hydraulic pressure of hydraulic oil supplied to bucket cylinder 7.
Using Pb, the horizontal resistance Rh and the vertical resistance Rv are derived using these detected values.

Now, assuming that the cross-sectional areas of the boom cylinder 5 and the bucket cylinder 7 are Sa and Sb, respectively, the cylinder forces Fa and Fb of the cylinders 5 and 7 are Fa = Pa · Sa (1) Fb = Pb · Sb (2) Becomes

Here, it is assumed that the resistance action point PD (XD, YD) changes in accordance with the rotation (rotation angle θ ₁ ) of the bucket 1 as shown in FIG. In the graph shown in FIG. 4, the vertical axis represents the distance DL between the tip point of the bottom plate of the bucket and the resistance action point PD,
The horizontal axis is the bucket rotation angle θ ₁ , θh (fixed value) is the angle at which the side edge 1a of the bucket 1 is horizontal, and Lc is the length of the side edge 1a portion.

Here, considering the XY coordinates centered on the pin P ₀ , the coordinates of the pin P ₁ before the bucket 1 is rotated are respectively (X ₁ ′,
Y ₁ ′), the coordinates (X ₁ , Y ₁ ) of P ₁ after the boom 3 has rotated θ ₂ are If the illustrated distance between the bucket pin P ₁ and the tip of the bucket bottom plate is l ₁ and the angle between the bucket bottom plate and the side edge 1a of the bucket is ψ, the bucket 1 and the boom 3 rotate by θ ₁ and θ ₂ respectively. Coordinate of the PD after (XD, Y
D) becomes XD = X ₁ + l ₁ · cos θ ₁ −DL · cosψ… (4) YD ＝ Y ₁ + l ₁ · sin θ ₁ −DL ・ sinψ… (5), and based on the graph in Fig. 4, θ ₁ . PD after θ ₂ rotation
The coordinates of can be specified.

Now, assuming that the dimensions shown in FIG. 3 are L ₁ , L ₂ , L ₃ , L ₄ and L _5, and considering the balance of moments around the pin P ₀ , Pv · XD + Rh · YD−Fa · L ₄ −Fb · L ₅ = 0 (6), and considering the balance of the moment around the pin P ₁ , Rv · (XD + X ₁ ) −Rh · (Y ₁ −YD) −Fb ′ · L ₃ = 0… (7 ) Become. Also Therefore, Rh and Rv can be obtained by solving these equations (6), (7) and (8).

Next, an automatic excavation device having such an embodiment configuration will be described with reference to the flowchart shown in FIG.

In this embodiment, three setting values Rh are set for the horizontal resistance Rh.
Set u, Rhd and Rhm (Rhu>Rhm> Rhd). Also,
Regarding the vertical resistance Rv, the set value Rvs as shown in FIG.
To set. That is, the vertical resistance setting value Rvs is the vertical resistance R
When considering the moment around the front wheel due to v, the horizontal component of the distance from the front wheel to the center of gravity of the bucket changes with the rotation of the boom 3, so the moment around the front wheel due to the vertical resistance Rv is constant. Therefore, it is changed as shown in FIG. 6 according to the height y of the bucket pin P ₁ (bucket pin height with 0 at the start of excavation). The sixth
In the figure, ya is the set value of the pin height at the end of excavation.

When performing automatic excavation, the operator turns on the automatic excavation mode switch 11, then starts the engine, sets the gear to, for example, the first speed, and runs the vehicle on the embankment (step 100). In this first excavation stage, horizontal plunge (penetration) excavation is carried out in which the vehicle travels while the boom 3 and the bucket 1 are stopped at the initial positions. When the microcomputer 10 detects that the switch 11 is turned on, the microcomputer 10 fetches the detection values θ ₁ , θ ₂ , Pa and Pb of the bucket angle sensor 2, the boom angle sensor 4, the hydraulic pressure sensor 6 and the hydraulic pressure sensor 8, respectively, and detects these detection values. Is used to calculate the horizontal resistance Rh and the vertical resistance Rv according to the method described in FIGS. 3 and 4 (step 110). Then, the microcomputer 10 first compares the calculated horizontal resistance Rh with the set value Rhm (step 120). If Rh ≦ Rhm, the process returns to step 100, and steps 100 and 110.
Repeat step. That is, from the start of excavation until the Rh exceeds the upper limit set value Rhm, the boom 3 and the bucket 1 do not rotate and the plunge excavation in the horizontal direction is performed. As a result, the horizontal resistance Rh applied to the bucket 1 gradually increases as shown in FIG. 7 (I).

After that, when the microcomputer 10 detects that Rh> Rhm by comparing in step 20, the switching signal S ₂
The switching valve 40 is switched by outputting
The oil pressure of the C pump 25 is sent to the tilt side spool 29 of the bucket control valve 22, and the bucket cylinder 7 is driven to the tilt side to start the tilt operation of the bucket 1 (step 130). As a result, the horizontal resistance Rh gradually decreases as shown in FIG. 7 (II).

Next, the microcomputer again calculates the horizontal resistance Rh and the vertical resistance Rv (step 140), and unless the stroke end of the bucket cylinder 7 is detected (step 150), this time the calculated vertical resistance Rv is set to the above-mentioned first value. Compared with the vertical resistance setting value Rvs shown in FIG. 6, and if Rv ≦ Rvs, the calculated horizontal resistance Rh is further compared with the lower limit setting value Rhd of the horizontal resistance (step 170). Then, as a result of this comparison, when the horizontal resistance Rh is larger than the lower limit set value Rhd (Rh> Rhd), the microcomputer 10 continues to send the switching signal S ₂ and further tilts the bucket 1 (step 130). ). After this, Rv ≦ Rvs and Rh> Rhd
, The microcomputer 10 continues to send the switching signal S ₂ and further tilts the bucket 1.

However, as a result of the comparison in step 170, the horizontal resistance Rh
Is smaller than the lower limit set value Rhd, the microcomputer 10 stops the transmission of the switching signal S ₂ to temporarily stop the tilt movement of the bucket 1, and this time outputs the switching signal S ₁ to switch the switching valve 30. And the hydraulic pressure of the POC pump 25 is sent to the upper spool 28 of the boom control valve 21 to drive the boom cylinder 5 to the upper side (raise) to raise the boom 3 (step 180).
Due to the rise of the boom, the horizontal resistance Rh is in the direction of increasing as shown in FIG. 7 (III).

Next, the microcomputer 10 again sets the horizontal resistances Rh and Rv.
Is calculated (step 190), and unless the boom angle θ ₁ exceeds a predetermined set angle (step 200), the calculated vertical resistance Rv is compared with the set value Rvs (step 210), and Rv is calculated.
If it is not> Rvs, the calculated horizontal resistance Rh is further compared with the upper limit set value Rhu of the horizontal resistance (step 22).
0). Then, as a result of this comparison, when the horizontal resistance Rh is less than the upper limit setting value Rhu (Rh ≦ Rhu), the microcomputer 10 first compares the horizontal resistance Rh with the previously calculated horizontal resistance value Rhp (step 230). When the result of this comparison is Rh ≧ Rhp, the microcomputer 10 continues to send the switching signal S ₁ and further raises the boom 3 (step 180). After that, the microcomputer 10 continues to send the switching signal S ₁ as long as Rv ≦ Rvs, Rh ≦ Rhu, and Rh ≧ Rhp, and raises and rotates the boom 3.

Then, the microcomputer 10 stops the transmission of the switching signal S ₁ at the time when the comparison result in step 220 is Rh> Rhu, that is, when the horizontal resistance Rh exceeds the upper limit set value Rhu, and the boom 3 of the boom 3 is stopped. While stopping the rising motion,
This time, the tilt motion of the bucket 1 is restarted by outputting the switching signal S ₂ (step 130). The tilting of the bucket causes the horizontal resistance Rh to drop again as shown in FIG. 7 (IV).

In the microcomputer 10, the boom 3 described above is used.
The horizontal resistance Rh during the rising of the
When it becomes smaller than p (Rh <Rhp), the sending of the switching signal S ₁ is stopped in the same manner as described above to temporarily stop the rising motion of the boom 3, and this time, the switching signal S ₁ is output and the bucket 1 is output.
Is tilted (step 130). That is, while the boom is being driven upward, the horizontal resistance Rh may drop slowly without reaching the upper limit set value Rhu of the horizontal resistance. In this case, the boom has insufficient horizontal excavation resistance Rh due to load. It will continue to be raised. Therefore, while the boom is rising, step 230
, The horizontal resistance value Rh calculated immediately before the current horizontal resistance value Rh
By detecting the fall of the horizontal resistance Rh by comparing with p,
When the lowering is detected, the horizontal resistance value Rh is forcibly reduced to the lower limit setting value Rhd by stopping the boom rising motion and tilting the bucket as shown in FIG. 7 (V), and then, The horizontal resistance value Rh is increased to the upper limit setting value Rhu by raising the boom again. Therefore, the microcomputer 10 saves and stores the sequentially calculated horizontal resistance Rh.

By alternately repeating the boom raising drive and the bucket tilt drive in this manner, the horizontal resistance Rh reciprocates between the upper limit setting value Rhu and the lower limit setting value Rhd. If the vertical resistance Rv becomes larger than the set value Rvs during the switching drive, the microcomputer 10 detects this in step 160 or step 210, and then shifts the procedure to step 240. That is, when Rv> Rvs is detected in step 160, the microcomputer 10 advances the procedure to step 240 by continuing to send the switching signal S ₂ , and in step 210 Rv> Rvs.
> When Rvs is detected, stop sending the switching signal S ₁ ,
And step the procedure by outputting the switching signal S _2.
Try to move to 240.

Then, after this, the microcomputer 10 tilts the bucket 1 by a predetermined angle by continuing to output the switching signal S ₂ until the end of a predetermined excavation, and then ends the present excavation operation (step 250). As a detection method at the end of excavation, a method is used in which the time when the sand edge 1a of the bucket 1 becomes horizontal is the end of excavation, and a time when the ground height of the bucket pin P ₁ is a predetermined height is the end of excavation. And a method of detecting the stroke end of bucket shilling.

Further, when the control means detects the stroke end of the bucket cylinder (step 150) or the boom angle exceeds a predetermined set value (step 200).
For this purpose, the procedure moves to step 240, and then the excavation operation is ended. This is because the excavation operation may not end indefinitely only by the switching control based on the comparison between the horizontal resistance value Rh and the vertical resistance value Rv and the set values Rhd, Rhu and Rvs. I chose

Furthermore, in the control means, first, the horizontal resistance Rh is compared with a set value Rhm which is a value smaller than the upper limit set value Rhu,
The bucket tilt motion was started when Rh> Rhm. That is, at the start of excavation, the vehicle speed is too fast, so the start of rotation of the bucket is delayed, and as a result, tire slip and the like often occur.As a countermeasure against this, the horizontal resistance Rh is reduced at the beginning of excavation. By comparing with the set value Rhm smaller than the upper limit set value Rhu, the bucket rotation start timing is intentionally accelerated. Of course, it is desirable to take such a countermeasure, but the set value Rhm may be substituted by the upper limit set value Rhu, and only the upper limit set value Rhu and the lower limit set value Rhd may be set for the horizontal resistance.

According to this embodiment, the upper limit and the lower limit set values Rhu and Rhd are set for the horizontal resistance, the set value Rvs as shown in FIG. 6 is set for the vertical resistance, and the sequentially detected horizontal resistance Rh and the upper limit are set. And the lower limit set value are compared, the horizontal resistance Rh is reciprocated between the upper limit set value Rhu and the lower limit set value Rhd by alternately performing the tilting operation of the bucket and the raising and rotating of the boom. Since automatic excavation such as tilting the bucket is performed from the detection value Rv of the resistance exceeding the set value Rvs to the end of predetermined excavation, problems such as tire slip and insufficient excavated soil volume occur. It is possible to automatically excavate a predetermined amount of earth and sand without always. Also, according to this automatic excavation control, the actuator that is operating is always either the bucket cylinder or the boom cylinder, so the hydraulic circuit with the fixed flow rate tandem circuit configuration, which is the current mainstream model, is installed. It is possible to realize an automatic excavating machine capable of efficient excavation by only partially changing the internal configuration of the loaded loading machine.

In the above embodiment, the upper and lower limit setting values Rhu and Rhd of the horizontal resistance and the vertical resistance setting value Rv may be arbitrarily changed each time excavation is completed.

Moreover, the calculation method for obtaining the horizontal resistance Rh and the vertical resistance Rv is not limited to the method described with reference to FIGS. 3 and 4, and for example, the load applied to the bucket by a load cell such as a load cell may be used. Alternatively, Rh and Rv may be determined based on the balance between the detected values and the forces of the horizontal and vertical resistances Rh and Rv.

The loading machine to which the present invention is applied is not limited to the wheel loader, and other pay loaders, tractor excavators, etc.
It is applicable to all machines having a boom and a bucket as work implement actuators.

〔The invention's effect〕

As described above, according to the present invention, (1) the boom drive and the bucket drive are controlled to be switched according to the excavation resistance, so that the excavation resistance does not become excessive, which prevents tire slip. It can prevent and extend the life of the tire,
Can greatly improve excavation efficiency (2) Regardless of operator's experience and skill, can always excavate a uniform amount of soil (3) Actuator is always operating in bucket and boom Since either one of them is used, the present invention has excellent effects such as being suitable for application to a loading machine having a tandem circuit configuration, which is the current mainstream.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of the overall control configuration of an apparatus according to an embodiment of the present invention, FIG. 2 is a side view showing the external configuration of a wheel loader and an example of the arrangement of each sensor, and FIG. FIG. 4 is a diagram for explaining a calculation example for obtaining the resistances Rh, Rv, FIG. 4 is a graph showing an example of a set movement locus of the resistance action point used in the calculation example, and FIG. Flow chart showing an example of action, Fig. 6 shows vertical resistance setting value
FIG. 7 is a graph showing the relationship between Rvs and bucket height y, and FIG. 7 is a diagram showing changes in horizontal resistance by the apparatus of this embodiment. 1 ... Bucket, 2 ... Bucket angle sensor, 3 ... Boom, 4 ... Boom angle sensor, 5 ... Boom cylinder, 6,
8 …… oil pressure sensor, 7 …… bucket cylinder, 10 …… microcomputer, 20 …… hydraulic circuit, 21 …… boom control valve, 22 …… bucket control valve, 23 …… tank, 24 …… work equipment pump, 25 …… POC pump, 26 …… Lift pilot valve, 27 …… Tilt pilot valve, 28,29 …… Spool, 30,40 …… Switching valve.

Claims (5)

[Claims] Claim: What is claimed is: 1. An automatic excavation device for a loading machine, which excavates a vehicle by automatically controlling the boom and the bucket while the loading machine having the boom and the bucket is running. A unit for sequentially calculating a component and a vertical component; a setting unit for setting a first set value, an upper limit set value, and a lower limit set value for the horizontal excavation resistance, and for setting a set value for the vertical excavation resistance; When the calculated horizontal excavation resistance is larger than the first set value and the calculated vertical excavation resistance is smaller than the set value of the same vertical excavation resistance, the horizontal excavation resistance is set to the upper limit set value and the lower limit set value. Alternate switching control of the tilting movement of the bucket and the raising rotation of the boom is performed so as to reciprocate between the vertical excavation resistance and the vertical excavation resistance calculated above. In order to allow the bucket to tilt until the end of the predetermined excavation after the resistance becomes greater than the set value, the product is equipped with a switching control means for controlling the switching of each work implement valve that drives the boom and the bucket. Automatic drilling equipment for embedded machines. 2. The automatic excavation of the loading machine according to claim 1, wherein the first setting value set in the setting means is a value between a lower limit setting value and an upper limit setting value. apparatus. 3. The first setting value in the setting means is set to the same value as the upper limit setting value.
An automatic excavator for a loading machine according to the item. 4. The switching control means calculates when the calculated horizontal excavation resistance is larger than a first set value and the calculated vertical excavation resistance is smaller than a set value of the same vertical excavation resistance. When the horizontal excavation resistance exceeds the upper limit set value and is falling to the lower limit set value, the bucket is tilted, and the calculated horizontal excavation resistance is smaller than the lower limit set value and then rises to the upper limit set value. The automatic excavating device for a loading machine according to claim (1), wherein switching control of each of the work machine valves is performed so as to sometimes raise and rotate the boom. 5. An automatic excavating device for a loading machine that excavates by automatically driving and controlling a boom and a bucket while a loading machine having a boom and a bucket is running. A means for sequentially calculating the vertical and vertical components, and a detecting means for detecting a decrease in the horizontal excavation resistance during the boom ascending drive by comparing the calculated horizontal excavation resistance with the previously calculated horizontal excavation resistance during the boom ascent. Setting means for setting a first set value, an upper limit set value, and a lower limit set value for the horizontal excavation resistance, and setting a set value for the vertical excavation resistance, and the calculated horizontal excavation resistance being the first setting. If the calculated vertical excavation resistance is larger than the value and the calculated vertical excavation resistance is smaller than the set value of the vertical excavation resistance, the calculated horizontal excavation resistance is calculated. When the resistance exceeds the upper limit set value and then falls to the lower limit set value, or when the detection signal is output from the detection means, the bucket is tilted, and the calculated horizontal excavation resistance becomes smaller than the lower limit set value. When the vertical excavation resistance calculated above becomes larger than the set value of the vertical excavation resistance, the bucket tilts until the end of predetermined excavation. An automatic excavating device for a loading machine, comprising: a switching control unit that controls switching of each work machine valve that drives a boom and a bucket, respectively, in order to perform movement.