WO1991013215A1

WO1991013215A1 - Excavator with automatic parallel positioning of its manually controllable working tool and arm system by means of sensors

Info

Publication number: WO1991013215A1
Application number: PCT/EP1991/000377
Authority: WO
Inventors: Wilfried Güthoff
Original assignee: Friedrich Wilhelm Schwing Gmbh
Priority date: 1990-03-02
Filing date: 1991-03-01
Publication date: 1991-09-05
Also published as: DE4009163A1; JPH04505488A

Abstract

An excavator with automatic parallel positioning of its manually controllable working tool and arm system by means of sensors consists essentially of a boom rocker articulated to an upper carriage and a handle which can pivot in the vertical pivoting plane of the boom rocker and which is articulated to the working tool, preferably a dipper shovel. The excavator also has a control system for the parallel positioning containing a tool sensor which detects the position of the working tool, a reference value setter and a comparison stage with co-operates with the sensor of the arm system. The manual control system (21) of the working tool adjusts the reference value setter (PH?) and therefore, synchronously and proportionally, the tool sensor (PS?), and the arm system is controlled by means of its sensors (PF?, PM?).

Description

Excavator with automatic parallel holding of its manually controllable work tool and arm system by sensors

description

The invention relates to an excavator with automatic parallel holding of its manually controllable working tool and arm system according to the preamble of claim 1.

The excavator according to the invention can be used for various work tools, e.g. for spiked rollers with which seeded embankments are processed. It is preferably used for digging with a backhoe, whereby working levels running parallel to the standing level can be worked on, but also upward or downward slopes. The arm system of the excavator according to the invention comprises at least the boom and the arm to which the working tool is articulated. The upper carriage forms the abutment of the jib. This includes a part of the excavator that is either pivotable or movably arranged on a stationary substructure. Or the swiveling superstructure sits on a chassis that is equipped with caterpillars or wheels.

In particular and preferably, the invention relates to excavators of the latter type, in which a two-part, bent boom in the form of a rocker arm is used, which in conjunction with a stick of corresponding length results in an arm system of maximum reach as soon as the arm system is stretched. Such excavators work particularly efficiently on extensive excavation levels, but on the other hand allow normal road transport with a folded arm system. The arm system of the excavator according to the invention is actuated regularly with the aid of hydraulic working cylinders which form the swivel drives. The required swivel angle can be made possible by connecting the piston rods of such working cylinders to handlebar systems or to cantilever arms of the arm system.

The hydraulic working cylinders of the swivel drives of the working tool and the arm system are actuated by the excavator operator via directional control valves via the manual control on the cabin, which is usually arranged on the uppercarriage. In an excavator of the preferred embodiment according to the invention, the excavator operator has the option of controlling all three working cylinders of the working tool and the arm system independently of one another with the manual control.

Before the digging movement of such an excavator can be initiated by the excavator operator, the operator must stretch the arm system so far that the working tool reaches its starting position, which does not always correspond to the maximum range of the arm system. The excavator operator must then pivot the work tool into a position that is to be regarded as favorable. If the working tool is designed as a backhoe, it has a knife for peeling off the bottom, which is often equipped with teeth and forms a guide surface with the adjoining bottom plate, which, due to the selected position relative to the bottom, forms the so-called cutting angle forms. This depends, among other things, on the hardness of the material to be mined. As a result of the parallel posture provided in the excavator according to the invention, the excavator driver mostly controls the boom or the stick with one of the swivel drives, the control system correcting the drive of the working tool. At the beginning and at the end of the excavation movements, the excavator operator must be able to change the position of the working tool, for example to fill a bucket, to empty it or to set it before the start of excavation. For this reason, the excavator driver has the option of actuating the swivel drive of the work tools, which is usually also in the form of a hydraulic working cylinder, with the control.

Typically, the operator of the excavator must make corrections to the work tool while digging. This results from the fact that the harder the soil, the greater the hardness of the ground and the difference in hardness along the gravel path is the rule. If you start the digging process e.g. in the harder ground with the correct cutting angle and leaves it unchanged along the grazing path, the knife or its guide surface in the softer ground section penetrates deep into the ground unintentionally. Conversely, with an optimal cutting angle for the soft bottom part of the scraping straight in the hard section, there is no removal because the cutting angle is too small. The spoon simply slides over the prospect. Possibly. the superstructure with its substructure is even brought into a tilt position. Without correcting the cutting angle during the

The digging process remains in hard areas of the Mountains and in soft spots of the

Valleys back. The desired flat surface is not achieved. If the excavator operator continually adjusts the hardness differences according to the cutting angle, a level scraping surface is finally achieved with the specified inclination.

Experience shows that the excavator operator is only able to control the three swivel angles of the arm system with great effort and great skill, so that the grazing level coincides with a predetermined level. If, however, greater accuracy and economic working speed are to prevail over the entire possible excavation path, technical aids must be made available to him, especially to the mediocre excavator operator. The excavator according to the invention therefore has the aforementioned parallel holding of its working tool. This ensures that the working tool is kept parallel to itself during the excavation by swiveling in a vertical plane, so that the excavator operator only needs to carry out the minimal pulse-like correction control for optimizing the cutting angle after the inclination of the digging plane has been determined.

The invention differs from such backhoe excavators, which mechanically force the work tool to remain parallel (DBP 18 00 045). In these excavators, the arm system is designed so that a hydraulic cylinder used to pivot the bucket on the one hand near the pivot axis of the dipper arm on the boom and on the other hand near the The pivot axis of the bucket engages the triangular bellcrank mounted on the dipper stick in such a way and the bellcrank is connected to the bucket via a short link so that the dipper stick, the bellcrank and the hydraulic cylinder together with the front end of the boom form a large four-bar linkage; this is coupled via a deflection triangle formed by the triangular deflection lever to a small quadrilateral joint formed by the deflection lever, the end of the dipper arm, the dipper arm and the short link; for a given length of the boom and for a given length of the dipper stick, the dimensions of the four-bar linkage and the deflecting triangle are coordinated with one another, and the large four-bar linkage is changed and adjusted in this way when adjusting the cutting angle of the bucket to the inclination of a slope to be worked with the help of the hydraulic cylinder adapted to the slope inclination, that the bucket during the digging movement taking into account that corresponding to the slope slope

Swiveling movement of the boom is guided in parallel over the entire swivel range of the dipper stick along the slope. Here the preselected cutting angle inevitably results from the geometry of the arm system. The excavator operator therefore only has to operate the digging movement with a hydraulic cylinder on the excavator's excavation device and must overlay the corrections described.

Because the invention provides sensors for the control, it is independent of the geometry of the arm system. Therefore, the restrictions on the length of the dipper stick, which are required in the mechanical solution described, are eliminated and results from the dependence of the dipper arm length on the stroke of the working cylinder, which swivels the working tool and therefore specifies the smallest dipper arm length. Larger lengths are also possible in the known system, but require additional links corresponding to the change in length between the large and small four-bar linkage. This means additional masses with a large projection of the arm system, which reduce the useful content of the bucket and reduce the optimal possible reach.

Additional handlebars with hydraulic parallel posture can be avoided, in which the parallel guidance of the work tool is forced with an additional hydraulic drive, a so-called master cylinder (DBP 24 39 967). But this is also associated with the disadvantage of too high a technical outlay, the parallel guidance also degenerating at dipper arm rotation angles of over 100 °. This limits the extension of the arm system and thus the range. These are canceled when sensors are used.

The invention is based on a previously known excavator of the latter type (DE-OS 31 34 064). Here, the cutting angle of the work tool is determined via a pendulum, which adjusts a potentiometer, which together with the pendulum forms the tool sensor, which is the respective one

Should convert the angle of intersection into a resistance value proportional to this. A manually adjustable potentiometer supplies the controller with the setpoint, which is converted into a controlled variable in a comparison stage, which controls a directional valve via a driver that controls the rotary actuator of the working tool forming working cylinder. The control of the arm system is separate from this. The pressure in the swing cylinder of the boom is preselected using a potentiometer forming the boom sensor and is kept constant using a pressure valve.

In such a control the

Cutting angle of the work tool primarily from the setpoint-actual value comparison. However, the creation of the controlled variable requires that there is actually a defined difference between the setpoint and the actual value. As a rule, i.e. in the case of non-homogeneous soils, which require one or more changes in the cutting angle in the course of the scraper movement of the bucket, the cutting angle and thus the actual value of the control must be adjusted in order to steer the bucket deeper into the soil or out of it to steer upwards. Since keeping the cutting angle parallel requires a significant change in the actual value in order to form a controlled variable, problems arise especially when changing direction, i.e. when cutting in and out, because a subsequent delay between hand action and bucket movement reaction causes the excavator operator to act after initially restrained activation Finally, without effect, the control hand lever is deflected, which means more power or more speed on the swivel drive addressed. His

Aggressive control intervention has the consequence, however, that the correction manipulated variable goes far beyond the desired level and movement sequences for correction control in the described and desired form become practically impossible. The invention has for its object to provide in a simple manner an excavator of the type mentioned, which, while avoiding the disadvantages mentioned, enables movement of the working tool, in particular thus a grazing straight line, irrespective of the ground conditions, which deviates from the predetermined ideal line only to a negligible extent without having to place excessive demands on the excavator operator in terms of time and skill.

The invention achieves this object with the features of claim 1. Further features of the invention are the subject of the dependent claims.

Since, according to the invention, the setpoint adjuster and thus the tool sensor can be adjusted synchronously and proportionally with the manual control of the work tool, every control measure, for example the cutting angle of a bucket, is carried out by the excavator operator so that the control remains unchanged, ie the parallel position is also enforced when the cutting angle is changed. Since the arm system is controlled with the aid of its sensors and the control only intervenes in the drive of the work tool if the actual value changes sufficiently, the excavator operator can dig out a hard ground section with a correspondingly enlarged cutting angle and then support it again with a reduced cutting angle continue to mine the control system, since the deviations from the setpoint and actual value according to the invention are independent of the control intervention in the drive of the working tool and do not influence the control system. It has been found that this control of the excavator according to the invention completely avoids the incorrect control of the working tool which has hitherto occurred under inhomogeneous soil conditions. Even inexperienced excavator operators can use the manual control of the work tool at any time

Change and precisely adjust the cutting angle without bringing the work tool to the ideal line in the wrong position. The arm system of the

Excavators can nevertheless have maximum lengths and are completely independent of their geometry. It can also not be overloaded by the excavator operator because the manual control changes the setpoint and actual value of the work tool simultaneously and proportionally.

According to the embodiment according to claim 2, the control is further simplified in that the determination of the actual value by a measuring device is omitted in that the work tool is used to adjust the tool sensor. This makes the control independent of the inevitable fluctuations in measured values, which is particularly problematic in the case of the known inclinometers.

Preferably works in the invention

Excavators also control with potentiometers. According to the features of claim 3, resistance values serve as measured values, which control the controlled system via a bridge circuit.

The details, further features and other advantages of the invention result from the following description of an embodiment with reference to the figures in the drawing; show it 1 shows an excavator according to the invention in a side view at the beginning of the excavation movement after the basic adjustment by the excavator operator before the initiation of the excavation movement,

Fig. 2 in Fig. 1 corresponding representation

different positions of the arm system and the deep-sea ice during the digging movement,

3 in the representation corresponding to FIG. 2, working tool and scraping movement along a sloping embankment,

Fig. 4 in Figs. 2 and 3 corresponding representation, the position of the parts described when digging on a rising

Embankment,

Fig. 5 is a hydraulic control according to the invention, partly in the form of a

Circuit diagram with symbols and partly with a schematic representation of the hydraulic lines and directional valves, as well as the connection of hydraulic working cylinders,

Fig. 6 is a block diagram of the electrical sensors of the excavator control and

Fig. 7 is a schematic representation of the deep-sea ice, which is used in the embodiment of FIGS. 1 to 4.

According to the illustration in FIGS. 1 to 4, the excavator according to the exemplary embodiment has an arm system which is supported on an uppercarriage (1). This can be pivoted about a vertical axis on an undercarriage (1 '). The arm system essentially has a cantilever rocker arm (2) articulated on the superstructure (1) at (4) about a horizontal axis, which is designed in two parts and bent downwards. The boom system also consists of the arm (5) which can be pivoted in the vertical plane, just like the boom rocker arm (2). While the boom rocker arm (2) is actuated with the help of the working cylinder (3) which is articulated on the one hand on the superstructure (1) and on the other hand on the inner part of the boom rocker arm (2), a working cylinder (6) is used to pivot the arm (5). , which is articulated on the one hand on a cantilever arm of the arm (5) and on the other hand on a bracket of the boom rocker arm (2). At the free end of the arm (5) there is a bucket (8) which can be pivoted about its pivot point (10) on the arm (5) via a working cylinder (9) and a lever system. The cutting angle shown can be changed using the working cylinder (9).

A comparison of FIGS. 1 to 4 with each other shows that there are different angles α, β and γ when the arm system and the bucket (8) are set to different embankment angles.

These angles can be picked up directly in the articulations (4, 7 and 10) by means of electrical sensors which are implemented with potentiometers. 6 the sensors are shown in the form of an electrical circuit diagram. The sensors p _H and p _S reflect the setpoint and the actual value of the cutting angle on the work tool (8). In the circuit diagram of FIG. 6, both sensors are assumed to be 3 kOhm, for example. A control measure at the low Spoon (8) by the driver changes both sensors simultaneously by the same amount, for example

2 kOhm or to 5 kOhm, whereby the adjustment remains unchanged. The control unit that causes parallel holding therefore remains unactuated.

Setpoint changes occur only by adjusting the sensors p _F and / or p _M as a result of actuations of the working cylinders (3 and / or 6) of the arm system, which means that the electronic control system

Working cylinder (9) and thus the resistance value of the sensor p _S changed so that the sum of p _S + p _M + p _F = 17 kOhm is retained in the example according to FIG. 6. This can lead to a deviation of p _H from pg. However, this is irrelevant for the control unit. Subsequent manual adjustment still changes p _H and pg simultaneously by the same value, for example by 2 kOhm, so that if before manual adjustment

p _S = 5 kOhm and p _H was still = 3 kOhm, this after manual adjustment p _H = 5 kOhm

p _S = 7 kOhm, so the sum is 19 kOhm on both branches of the bridge. The comparison is consequently also not disturbed by the manual adjustment, the control unit remains idle.

The described synchronous and proportional

Adjustment of the setpoint adjuster p _H and the tool sensor p _S with the manual control of the excavator is shown in FIG. 5.

The control device shown has a hand lever (21) which actuates a multi-way valve (24) via hydraulic lines (22 and 23), as a result of which the working cylinder (9) can be adjusted via the lines (25, 25a and 26). For completion, the hydraulic pump (36), the required pressure relief valve (37) and the hydraulic oil tank (38) are shown symbolically in the figures. In this way, the boom cylinder (3) and the working cylinder (6) for actuating the arm (5) are controlled, the cylinder force and the cylinder speed being proportional to the size of the deflection angle in the hand lever. The invention is based on obtaining this hand control for the excavator operator. As a result, the excavator operator can, as usual, assume that, depending on the design of the hand lever of the control (21), a corresponding reaction, e.g. on the working cylinder of the deep-sea ice (9).

According to FIG. 5, the control device (21) is also used to set the target value. As a result, apart from the parallel holding of the bucket caused by the control unit, the spoon can be brought into positions in which it is filled or emptied. A change in the sensor p _H (34) is carried out with a small actuating cylinder (35) is controllable at least in speed proportional to the hand lever adjustment. The bucket cylinder (9) is regulated via the hydraulic lines (28 and 29) via a multi-way valve (27) which is controlled electromagnetically. The values of all sensors according to FIG. 6 are present at the input of the driver (30). If there is a comparison, as shown, changes

initially nothing. However, if p _F or p _M or p _F + p _{M is adjusted} , then the control causes the driver to actuate the magnet (31 or 32) in the sense of a change in the sensor pg (33), so that the adjustment takes place.

The embodiment according to FIG. 5 does not allow the actual and setpoint values to lag as soon as the control (21) is actuated. In this case, the sensor p _H (34) required for specifying the setpoint is changed according to the invention with manual adjustment simultaneously with the sensor p _S in the same direction and in the same size. As with the sensor p _S (33), an auxiliary cylinder (35) is used for this. Its rod-side volume is equal to the piston-side volume of the bucket cylinder (9). The hydraulic line (25) is connected to the piston side of the auxiliary cylinder (35). The hydraulic line (25a) connects the rod side of the auxiliary cylinder (35) to the piston side of the spoon cylinder (9). Using a valve, which is not described in any more detail here, it is possible, for example, to completely extend the piston rods as the basic position on both cylinders.

By operating the hand lever on the control device (21), both piston rods of the auxiliary cylinders can then be switched on and off at the same time extend. Because each piston rod is coupled to a sensor (34 or 33), their values change just as synchronously as the rod positions. Via the hydraulic lines (28 and 29), which start from the multi-way valve (27), the

Bucket cylinder (9) adjusted so that the bucket (8) is permanently parallel.

The bucket cylinder (9) is adjusted via the hydraulic lines (25, 25a and 26) from the multi-way valve (24) when the starting position is set or when filling or emptying or correcting. The bucket (8) is thereby brought into any position, which is done sensitively, precisely and proportionally, the operator of a conventional excavator not having to relearn.

Another advantage of the invention results when the load limits are reached.

Basically, the components of a backhoe are protected against overloading by pressure relief valves in the hydraulic system. With conventional excavators, it is often the case that insurmountable obstacles in the floor mean that the bucket cannot be adjusted further, which means that no change is made to the sensor p _S either.

If, as usual with conventional excavators, the excavator operator adjusts the setpoint adjuster alone and the tool sensor cannot follow the specified reasons, the difference between the setpoint and actual value increases because the excavator operator tries to overcome the obstacle by repeatedly deflecting the hand lever.

If the spoon does come free for some reason, the regulation comes into force sets the actual value to the setpoint. In practice, there is often a rotation angle of approx. 100 ° on the spoon. These movements scare the excavator operator, who cannot control them, and may lead them to wrong reactions. This leads to danger to other people and damage to the excavator or other things.

Since, according to the invention, the sensor p _H (34) and the sensor p _S (33) are always changed together when manually adjusted, the hand lever at (21) can be actuated as often as required to overcome an obstacle. If the spoon cannot be moved, the sensor p _S (33) does not move and the spoon cylinder (9) remains unchanged. The position of the auxiliary cylinder (35) does not change, which is why the sensor p _H (34) is not adjusted. This prevents uncontrolled movements of the arm system or the working tools of the excavator.

Claims

1.Excavator with automatic parallel holding of its manually controllable work tool and arm system by sensors, which essentially consists of a boom swing arm articulated on an uppercarriage and a pivotable arm in the vertical swivel plane of the boom swing arm, to which the work tool, which is preferably designed as a bucket, is articulated and one Control, in which a tool sensor, which detects the position of the work tool, a setpoint adjuster and a comparison stage are provided for the parallel holding, which cooperates with the sensor of the arm system, characterized in that the setpoint adjuster (P _H ) and thus synchronously and proportionally the tool sensor (P _S ) is adjustable, and that the arm system is controlled with the aid of its sensors (P _F , P _M ).

2. Excavator according to claim 1, characterized in that the working tool (8) is used to adjust the tool sensor (P _S ).

3. Excavator according to one of claims 1 or 2, characterized in that the comparison stage on the one hand accumulation from the sensors (P _F , P _M ) of the arm system and the tool sensor

(P _S ), as well as the setpoint adjuster

(P _H ) and a sensor (P _St ) used to preset the arm system on a working level

has and the regulation can be triggered by forming the difference of the sums.

4. Excavator according to claim 1 and one of claims 2

or 3, characterized in that for the synchronous and proportional adjustment of the setpoint adjuster (P _H ) a hydraulic

Actuating cylinder (35) is provided.

5. Excavator according to claim 1 and one of claims 2 to 4, characterized in that the actuating cylinder (35) of the sensor (P _H ) is in hydraulic synchronization with the working cylinder (9) of the working tool (8), with which an actual value reproducing sensor (P _S ) is adjustable.

6. Excavator according to claim 1 and one of claims 2 to 5, characterized in that the manual control (21) of the working cylinder (9) of the working tool (8) via a pilot-operated directional valve (24), of which the actuating cylinder (35) of the Setpoint adjuster is adjustable.