EP0530530B1 - Tilt actuator for shovel - Google Patents

Abstract

Tilt actuator for a loading shovel or stacker fork of a shovel loader, which tilt actuator, to obtain a dumping movement which is at least as fast as the levelling movement as well as for the purpose of simple assembly and maintenance of the actuator, has a piston-rod extension (46a) which is guided in a sealed-off bore of the actuator base (43) and the diameter of which corresponds to at least that of the piston rod (46), the bearing lug (50) of the actuator and the actuator base being integrally connected to one another by a connection member (49) extending over the greatest extension length of the piston-rod extension (46a), and the receiving space (51) for the piston-rod extension containing a laterally open access for assembly or exchange of the guide and seals (44, 45) in the actuator base. <IMAGE>

Description

The invention relates to a tilt cylinder for the loading shovel of a shovel loader device on a work vehicle, the cylinder base of which is articulated by means of a bearing eye on the loading frame above a pivotable lifting frame and the piston rod of which is articulated by means of a bearing eye on a rocker arm mounted on the lifting frame such that the loading shovel indirectly connected to the rocker arm at constant cylinder extension length during pivoting movements of the lifting frame remains in an upwardly open tilt position, the cylinder having a piston rod extension guided in a sealed bore in the cylinder bottom, the diameter of which corresponds at least to that of the piston rod and the length of which corresponds at least to that of the maximum piston stroke.

From FR-A-2 050 169 it is known to control the tilting movements of a loading shovel by means of parallelogram kinematics, in which the tilting cylinder, the lifting frame, the loading frame having the articulation points therefor and a rocking lever movable on the lifting frame form a parallelogram with at least one cylinder extension length. The rocker arm connected to the loading shovel via a handlebar serves to increase the tilt angle of the Loading shovel. By suitably dimensioning the parallelogram, the loading shovel remains in its open position over the entire swivel range of the lifting frame. Even when the loading shovel is replaced by a stacker device, the cargo resting on the stacker fork remains approximately parallel to its receiving position during the pivoting movements of the lifting frame. This parallelogram kinematics is unsatisfactory insofar as the hydraulic pressure only acts on the differential area of the cylinder piston for tipping up or tipping in the loading shovel, for example when the load to be picked up is broken out, and the tipping movement is also slower than the tipping movement because the oil flow causes the filled loading shovel to tip out full piston cross section must act.

In contrast to this, in a so-called “Z” kinematics, the rocker arm is connected to the rocker arm at one end of the rocker arm, which in this case is mounted on the lifting frame between its ends, and the loading shovel is connected to the other end by means of a handlebar. Since the rocker arm reverses the cylinder movements, the full piston cross-section is available for tipping in the loading shovel and its differential area for tipping out. This favorable use of the cylinder force is offset by the disadvantage that the loading shovel or fork is not automatically kept parallel when the lifting frame is pivoted, but the tilting cylinder has to be readjusted several times.

From US-A-3 308 976 a shovel loader device is known, the loading shovel of which is mounted on the lifting frame without a rocker arm is directly adjusted by two identical parallel tilt cylinders, the free piston rod ends of which are connected to the loading shovel by means of bearing eyes. At its end extending through the piston, each piston rod carries an extension of larger cross-section which is screwed there and which, sealed by the cylinder base, projects into an extension tube flanged to the cylinder and connected to the loading frame by means of a bearing eye. These measures are intended to ensure that the tipping-in movement of the loading shovel is carried out with greater force and lower speed and the tipping-out movement of the loading shovel is carried out with less force and higher speed via the tilting cylinders.

The object of the invention is to design a tilting cylinder of the type specified at the outset in a parallelogram kinematics by cost-effective measures such that it executes the dumping movement of the loading shovel at least as quickly as the dumping movement and the design changes used for this are particularly simple, safe assembly and maintenance of the cylinder allow and increase its strength against buckling stress.

• daß das Lagerauge des Zylinders und der Zylinderboden durch ein sich über die größte Ausfahrlänge der Kolbenstangenverlängerung erstreckendes und gegenüber den Zylinderkräften zug- und druckfestes Anschlußglied integral miteinander verbunden sind,
• und daß ein im Anschlußglied zentrischer Aufnahmeraum für die Kolbenstangenverlängerung vorgesehen ist, der einen seitlich offenen Zugang zur Montage bzw. Austausch der Kolbenstangendichtungen im Zylinderboden enthält.

According to the invention, this object is achieved by

• that the bearing eye of the cylinder and the cylinder base are integrally connected to one another by a connecting member which extends over the greatest extension length of the piston rod extension and is tensile and pressure-resistant with respect to the cylinder forces,
• and that a central space in the connector for the Piston rod extension is provided, which contains a laterally open access for mounting or replacing the piston rod seals in the cylinder base.

In the case of the proposed design, the greater dumping speed of the loading shovel achieved in simple series cylinders due to the piston rod extension and the connecting member benefits from rational work, for example when loading trucks waiting at an excavation part. Since the connecting rod protecting the piston rod extension against external influences is welded to the cylinder base or otherwise forms a uniform component with it, an expensive flange connection which increases the diameter and space requirement is avoided, the safety of which is essential in the case of alternating tensile and compressive forces occurring in cylinder operation would depend on the care taken in fastening the flange screws. The resilience of the cylinder to pressure or buckling stresses is also ensured in that the piston rod is guided on both sides of the piston in the cylinder head and in the cylinder base. - The laterally open access in the connecting element is advantageous in several respects by allowing problem-free assembly and maintenance of the guide, seals and wiper rings in the cylinder base, which are subject to normal wear and tear. Furthermore, the piston rod extension is visible through the laterally open access, so that the vehicle driver can recognize the pivoting position of the loading shovel at any time based on their respective position. In addition, the piston rod extension assume the function of an otherwise additionally arranged measuring rod and can be used for the automatic adjustment of the loading shovel using sensing and control devices.

In one embodiment, the connecting element together with the bearing eye can have the shape of a tuning fork, the fork legs being made of flat or profiled steel, which are connected to the bearing eye and the cylinder base, and between the fork legs the receptacle for the piston rod extension contain. In another design, the connecting element can be designed as a simple firing, forged or cast part and permanently welded to the cylinder end - and possibly also form an integral, uniform component with the cylinder bottom. No special requirements are placed on the connection element with regard to surface processing, nor on its receiving space, which surrounds the piston rod extension with play.

The receiving space of the connecting member, which is open at least on one side, is expediently provided with a detachable cover. In the case of the tuning fork shape, for example, at least one cover plate can then be detached and enables access to the guide and seals in the cylinder base.

The piston rod extension can have a different diameter from the piston rod, and in the case of a piston rod that is smaller in diameter, it is either turned off by a single component or connected to the extension, e.g. is screwed. By suitable dimensioning of the diameter, the dumping speed can be increased as desired compared to the dumping speed of the loading shovel.

According to a variant, the piston rod extension forms a displacement measuring element for a switchable electrohydraulic control, by means of which the cylinder actuating movement (pivoting of the loading shovel) is stopped in one and / or the other direction at a certain point, in particular its Pick-up position with bucket bottom that generally runs parallel to the timetable (having the scraper edge) corresponds. This gives the driver the opportunity to switch on the electrohydraulic control whenever the loading shovel is to be swiveled automatically from any dumping position or from an upward tilted position as quickly as possible into the receiving position that is to be visited again regularly. - Embodiments of the electro-hydraulic control for a tilt cylinder according to the invention form the subject of claims 8 to 11.

Fig. 1a

einen Schaufellader mit erfindungsgemäßem Kippzylinder bei eingekippter Ladeschaufel,

Fig. 1b

den Schaufellader nach Fig. 1a mit in Aufnahmestellung auf dem Fahrplanum verschwenkter Ladeschaufel,

Fig. 1c

eine Ladeschaufel in Auskippstellung bei in verschiedenen Höhen verschwenktem Hubrahmen,

Fig. 2a

einen teilweise geschnittenen Kippzylinder nach der Erfindung mit eingefahrener Kolbenstange,

Fig. 2b

den Kippzylinder nach Fig. 2a mit in eine Mittelstellung ausgefahrener Kolbenstange, die der Aufnahmestellung der Ladeschaufel in Fig. 1b entspricht,

Fig. 2c

den Kippzylinder mit voll ausgefahrener Kolbenstange entsprechend einer Auskippstellung der Ladeschaufel, wobei der seitliche Zugang im Anschlußglied durch eine Abdeckplatte verschlossen ist,

Fig. 3

ein elektrohydraulisches Schaltbild der automatischen Steuerung eines Kippzylinders unter Verwendung eines Elektrotasters und

Fig. 4

eine durch Näherungsschalter abgeänderte elektrohydraulische Steuerung für einen Kippzylinder.

Exemplary embodiments of the invention are explained in more detail below with reference to the drawings. It shows, each schematically,

Fig. 1a

a shovel loader with a tipping cylinder according to the invention with the loading shovel tipped in,

Fig. 1b

1a with the loading shovel pivoted in the receiving position on the timetable,

Fig. 1c

a loading shovel in the tilted position with the lifting frame pivoted at different heights,

Fig. 2a

a partially cut tilt cylinder according to the invention with the piston rod retracted,

Fig. 2b

2a with the piston rod extended into a central position, which corresponds to the receiving position of the loading shovel in FIG. 1b,

Fig. 2c

the tilt cylinder with the piston rod fully extended in accordance with a tilting position of the loading shovel, the lateral access in the connecting member being closed by a cover plate,

Fig. 3

an electro-hydraulic circuit diagram of the automatic control of a tilt cylinder using an electric button and

Fig. 4

an electro-hydraulic control for a tilt cylinder modified by proximity switches.

1a to 1c, there is a loader frame 2 on the front of a shovel loader 1. A lifting frame 3, which can be pivoted in the vertical plane by means of a lifting cylinder 3a, has its bearing 9 on the loader frame 2. A tilting cylinder 4 is at its rear end a bearing 10 on the loader frame 2 and at its front end at 4a connected to a rocker arm 5, which is connected at 5a on the lifting frame 3 at its other end by means of a link 6 to the loading shovel 7.

1b shows the loading shovel 7, the shovel bottom 8 of which is located in parallel on or above the timetable. In this receiving position, the piston rod of the tilt cylinder 4 is partially extended, approximately to a central position. 1c shows the lifting frame 3 actuated by the lifting cylinder 3a in two different pivot positions, in which the loading shovel 7 is pivoted into its tipping position when the tilt cylinder 4 is extended. In a comparison it can be seen that when the loading shovel 7 is tilted open at the top according to FIG. 1a, the tilt cylinder 4 extends approximately parallel with respect to an imaginary connecting line between the bearing point 5a of the rocker arm 5 on the lifting frame 3 and the bearing 9 of the lifting frame 3. At the same time, imaginary connecting lines between the bearing points 9 and 10 and the bearing points 4a and 5a run essentially parallel to one another, so that, due to the parallelogram relationship described above, the tipped-in state of the loading shovel 7 is maintained over the entire pivoting range of the lifting frame 3. This parallelogram relationship does not exist in the blade positions according to FIG. 1b or 1c, since in FIG. 1b the direction of the tilt cylinder 4 deviates from the direction of the lifting frame or, according to FIG. 1c, the connecting line 4a-5a is a different direction than the connecting line 9-10 on the loader frame 2.

The tilting cylinder used for the shovel loader device is shown in detail in FIGS. 2a to 2c. It comprises a cylinder tube 41 with a cylinder head 42 and usual seals. The cylinder head 42 is detachably connected to the cylinder tube 41, a cylinder bottom 43 is welded into the other end of the cylinder tube 41, which is preferably an integral part of a connecting element 49 provided with a bearing eye 50. Seals 44 and wiper rings 45 for sealing an extended piston rod section 46a and possibly a guide (not shown) are arranged in the cylinder base 43.

On the piston rod 46, which can form a unitary component with the piston rod extension 46a passed through the cylinder base 43, a piston 47 with piston seals is attached approximately in the middle. The piston rod end protruding through the cylinder head 42 carries a screwed-on or welded-on bearing eye 48, depending on whether the piston 47 is fixed or detachably connected to the piston rod 46. The free end of the piston rod extension 46a can have a run-up slope 46b described in more detail in connection with FIG. 3. The piston rod 46 and its extension 46a can have the same or different diameters. The actual hydraulic cylinder, which is delimited by the cylinder head 42 and the cylinder base 43, contains hydraulic connections 11 and 12 at the end.

The connecting member 49 which extends the cylinder 4 on the side of its cylinder base 43 serves to support the cylinder or the introduction of force into the loader frame 2 and at the same time forms a protection for the piston rod extension 46a. For this purpose, the fork-like connecting member 49 contains, at a distance between its parallel legs 52, 53, a receptacle 51 which surrounds the piston rod extension 46a, which is completely retracted according to FIG. 2a, at a distance. 2a, 2b, the receptacle 51 is open at least on one side, so that it is possible to assemble or replace the seal 44 and the scraper ring 45 in the cylinder base when the piston rod is disassembled through the open access to the receptacle 51. The connecting member 49 integral with the bearing eye 50 can have as a flat part approximately the shape of a tuning fork, so that the receptacle 51 is open on both sides and is closed by removable cover plates to protect the piston rod extension 46a and its guides and seals. The connecting member 49, which is designed as a burnished, forged or cast part, can also have another shape, for example that of a tube or a bottle, which is cut open or flattened on at least one side and there forms the lateral opening of the receptacle 51. Preferably, as shown, the machined cylinder base 43 forms a unit with the legs 52, 53 by welding or other connection.

The half-extended position of the tilting cylinder in FIG. 2b corresponds approximately to that in FIG. 1b, where the loading shovel 7 takes up its receiving position with the shovel bottom 8 resting on the timetable. In Fig. 2c, the fully extended position of the piston rod 46 corresponds to that of the tilt cylinder in Fig. 1c, where the loading shovel assumes its tipping position. The cover 14 can serve as a receptacle for an electric button 13 described below, which projects into the path of the piston rod extension 46. The screwable cover 14 is longitudinally adjustable in a limited area via the elongated holes 19 indicated in FIG. 2c.

According to FIG. 3, a spring-loaded electric switch 13 with a front feeler roller 16 bears against the run-up slope 46b of the piston rod extension 46a, from which two further intermediate positions are indicated. The electric button is with a switchable contact tongue 17 of a two-pole switch 18 connected so that in the central position shown it leaves an electromagnetic switching valve 15 controlled by the switch 18 or its electromagnets 30, 31 unactuated. This electrohydraulic control of the tilting cylinder serves for the automatic return of the bucket to the receiving position (FIG. 1b) and is activated by a switch 20. When the power supply is interrupted, the switching valve 15 assumes its central blocking position determined by springs 32, 33. If the automatic bucket return is activated at the switch 20 after the loading bucket has been dumped (FIG. 1c, 2c), the button 13 assumes its lower end position. The contact 21/22 is closed, the magnet 30 is energized and the switching valve 15 in FIG. 3 is moved to the left, so that the cylinder port 11 is supplied with pressure oil and the piston rod 46 is retracted until the piston rod extension 46a is the same as that in FIG. 3 Position shown with solid lines (= cylinder state in Fig. 1b and 2b) reached, interrupts the circuit and blocks the tilt cylinder 4.

With the tilting cylinder fully retracted in accordance with FIG.

As a result, the piston rod 46 extends until the piston rod extension 46a reaches the position shown in solid lines in FIG. 3. - The lifting cylinder 3a is actuated independently of the tilting cylinder 4 via an arbitrarily controlled valve. As long as the switch 20 is not actuated, the tilt cylinder can be controlled via the valve 15 or via a valve connected in parallel with it.

4, two contactless proximity switches 25, 26 are arranged in the electrohydraulic control for automatic blade return into the receiving position on the connecting member 49 or on one or two opposing covers 14, which cooperate with a control edge 27 of the piston rod extension 46. The proximity switch 25 containing an opening contact 28 is offset by a small length in the direction of the cylinder base 43 with respect to the proximity switch 26 containing a closing contact 29. In order to automatically transfer the bucket either from the tipped position according to FIG. 1a or from the tipped position according to FIG. 1c into the receiving position according to FIG. 1b, the control is activated by actuating the switch 20.

If the control edge 27 is in the position indicated on the left in FIG. 4, the electromagnet 30 is excited via the normally closed opening contact 28 of the switch 25. Magnet 30 pulls the switching valve 15 against the action of its centering springs 32, 33 to the left, so that the port 11 of the cylinder 4 is pressurized with oil until the control edge 27 in the position shown in solid lines (= Cylinder state Fig. 1b and 2b) on the switch 25 through the opening contact 28 interrupts the power supply. When the piston rod extension 46a is automatically returned from a position indicated on the right in FIG. 4, the normally open closing contact 29 of the proximity switch 26 is closed, so that the electromagnet 31 is energized and the switching valve 15 counteracts the action of the centering springs 32, 33 pulls to the right, the port 12 of the cylinder 4 being supplied with pressure oil until the control edge 27 has moved away from the area of the switch 26, the contact 29 of which opens, so that the switching valve 15 reaches the centered blocking position shown.

Claims (11)

1. A scoop-and-dump jack for the loader shovel (7) of a shovel loader on a construction vehicle of which the jack's cylinder-bottom (43) hinges by a bearing eye (50) on the loader chassis (2) above a pivotable operational truss (3) and of which the piston rod (43) hinges by means of a bearing eye (48) on a rocker lever (5) resting in the operational truss, in such manner that the loader shovel (7) indirectly linked to the scoop-and-dump jack remains in an upwardly open pivoted position during the pivoting movements of the operational truss (3) while the extended length of the jack remains constant, whereby the jack (4) comprises a piston-rod extension (46a) guided inside a sealed borehole of the jack cylinder-bottom (43), the diameter of said extension corresponding at least to that of the piston rod (46) and of which the length corresponds at least to that of the maximum piston stroke,
   characterized in that,

   - the jack bearing-eye (50) and the jack cylinder-bottom (43) are integrally connected by a connection member (49) extending across most of the length of advance of the piston-rod extension (46a) and tensionally and compressively resistant to the jack forces,

   - and a central receiving space (51) for the piston-rod extension (46a) being present in the connection member (49), which comprises a laterally open access for assembly or exchange of the piston-rod seals (44, 45) in the jack cylinder- bottom.
2. Scoop-and-dump jack as defined in claim 1, characterized in that the connection member (49) together with two of its parallel legs (52, 53) starting from its bearing eye (50) is shaped like a tuning fork and in that the receiving space (51) for the piston-rod extension (46a) is in the form of the gap between the legs of which the ends are welded to the jack clyinder-bottom (43).
3. Scoop-and-dump jack as defined in claim 1 or 2, characterized in that the connection member (49) with the bearing is an integral roasted, forged or cast part.
4. Scoop-and-dump jack as defined in one of the claims 1-3, characterized in that the receiving space (51) of the connection member (49) and open at least on one side between the jack cylinder-bottom (43) and the bearing eye (50) comprises a detachable cover (14).
5. Scoop-and-dump jack as defined in one of the preceding claims, characterized in that the piston-rod extension (46a) evinces a larger diameter than the piston rod (46).
6. Scoop-and-dump jack as defined in one of the preceding claims, characterized in that the connection member (49) is welded by its integral cylinder bottom (43) to the jack case (41).
7. Scoop-and-dump jack as defined in one of the preceding claims, characterized in that the piston-rod extension (46a) forms a position sensor for an electrohydraulic control and initiates jack displacement for the loader-shovel's scooping and/or dumping motion and stops at a specific position preferably corresponding to the shovel scooping position with the shovel base (8) parallel to the plane of travel.
8. Scoop-and-dump jack as defined in claim 7, characterized in that an electric sensor (13) of the connection member (49) projects at a predetermined location into the path of the piston-rod extension (46a), the fee end of said extension comprising a ride bevel (46b) holding the electric sensor in a central position and in that the electric sensor is so connected to a contact blade (17) of a two-pole switch (18) that it remains OFF in its center position but when in its two end positions will drive the scoop-and-dump jack (4) by means of an electric switching valve (15) into displacement in either of the mutually opposite directions.
9. Scoop-and-dump jack as defined in claim 7, characterized in that one or more contactless proximity switches (25, 26) to reverse, as a function of displacement, a switching valve (15) controlling the scoop-and-dump jack are associated to the extended piston-rod segment (46a) along its displacement path in the connection member (49).
10. Scoop-and-dump jack as defined in claim 9, characterized in that a control edge (27) of the piston-rod extension (46a) at the connection member (49) cooperates with a proximity switch (25) containing an opening contact (28) to control one of the two electromagnets of the switching valve (15) and further with a proximity switch (26) containing a closing contact (29) to control the other electromagnet, the proximity switches being slightly mutually offset in the direction of displacement of the control edge.
11. Scoop-and-dump jack as defined in claim 7, characterized in that the position switches of the electro-hydraulic circuit are mounted on the cover means (14) of the connection member (49), the cover means being affixed in adjustable manner through longitudinally elongated slots (19).

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