EP2722529A1 - Device for limiting the stroke of an actuator, actuator and agricultural machine having such a device - Google Patents

Abstract

The stop (1) has moving parts (2, 3) connected by an elastic element (4) that is mounted against rods (10, 10A) of an actuator to limit a stroke of the actuator. Each moving part includes a cut-out part (6) corresponding to shape of the rod. The cut-out part includes a succession of surfaces (15) having circular section with different radii (R1-R3, RN). The radius of one of the surfaces corresponds to half of diameter (d) of the rod of the actuator. The surfaces are separated by an edge.

Description

The present invention relates to the general technical field of agricultural machinery. The invention relates to a device including an actuator stop comprising two moving parts connected by an elastic member adapted to be mounted on a rod to limit the stroke of the actuator, each movable portion having a cutout shaped to the shape of the rod. The invention also relates to an actuator comprising at least one stop limiting its travel, and an agricultural machine equipped with one or more actuators provided with at least one such stop.

Actuators are commonly used for applications in which the stroke of the actuator raises, lowers or holds a tool or a machine member in a specific position.

On agricultural machines, it is for example very common to use actuators such as cylinders to adjust the position or the working depth of a tool. Thus, a position of the tool corresponds to a certain cylinder length, that is to say a position of the piston in the body. When the piston is not at the end of stroke or in abutment, the position of the piston in the body is maintained via the fluid under pressure. During the operation of the machine, the piston can move in the body due to leaks in the circuit. Inadvertent movement of the piston, and therefore of the stem, affects the position or depth adjustment and may in some cases cause damage to the machine. It is thus known to set up a mechanical stop system on the rod of the actuator to provide a mechanical stop.

In the document US 6,314,860 it is proposed to use a mechanical stop in the form of a jaw. This jaw comprises two moving parts connected by an elastic member. To adjust the position or depth, the number and thickness of the stops on the actuator stem may vary. The adjustment is easy since the stops can be removed or added to the rod through the elastic member. When the stopper is mounted on the rod, it limits the entry of the rod into the body under the action of the fluid. The moving parts each have a cutout shaped to the shape of the rod. The section of the stem is usually circular and the radius of the cut must exactly correspond to the radius of the rod to ensure good contact between the cut and the rod.

It is known that the actuators that are used, for example on agricultural machines, are not all identical. Indeed, the stroke of the actuator is determined according to the displacement to be made while the diameter of the rod is directly related to the axial force developed by the actuator. It happens that the jaw used as a stop is not fitted to the cylinder rod. In this case, the contact between the cut and the rod is made only in a line. Such contact does not allow a reliable maintenance of the two jaws on the rod and the risk of disengagement of the stop is relatively important during use of the machine.

The present invention aims to overcome the aforementioned drawbacks and aims to provide a mechanical stop compatible with different rod diameters whose assembly is reliable and fast.

According to the invention, the stop is remarkable in that the cutting of one of the moving parts has a succession of circular cross-sectional areas of different radii and that the radius of one of the surfaces corresponds to half the diameter of the rod of the actuator. Thanks to the succession of surfaces, the same abutment is adapted for several diameters of stem. One of the surfaces of each cutout being adapted to the diameter of the rod, the mounting of the stop on the rod is therefore more reliable. The surface contact between the cut and the rod eliminates any relative movement of the stop on the rod and the risk of disengagement of the stop is reduced when using the machine or the actuator.

According to another important characteristic, the cutting of one of the moving parts has two successions of circular section surfaces of different radii and the surface with the smallest radius is common. With such a cut, maintaining the stop on the rod is provided by two surface contacts separated from one another around the rod.

• la figure 1 est une vue en perspective d'une butée selon l'invention,
• la figure 2 représente un actionneur sur lequel sont montées deux butées conforme à l'invention,
• la figure 3 est une vue de côté d'une machine agricole dans une position de travail présentant au moins un actionneur avec une butée selon l'invention,
• la figure 4 représente une vue en coupe de la tige de l'actionneur de la figure 2,
• la figure 5 est une vue en coupe d'une autre tige avec une butée selon une autre variante de réalisation de l'invention.

Other features and advantages of the invention will become apparent from the following description with reference to the accompanying drawings which are given by way of non-limiting examples of the invention. On these drawings:

• the figure 1 is a perspective view of a stop according to the invention,
• the figure 2 represents an actuator on which are mounted two stops according to the invention,
• the figure 3 is a side view of an agricultural machine in a working position having at least one actuator with a stop according to the invention,
• the figure 4 represents a sectional view of the rod of the actuator of the figure 2 ,
• the figure 5 is a sectional view of another rod with a stop according to another embodiment of the invention.

The figure 1 is a mechanical stop (1) consisting essentially of two moving parts (2, 3) and an elastic member (4). The two movable parts (2, 3) are connected by the elastic member (4). In the view shown, the elastic member (4) constrains the two movable parts (2, 3) against each other. This stop (1) is intended to be mounted on an actuator (5). Each movable part (2, 3) has a cutout (6) and a flared end (7) which facilitates the mounting of the stop (1) on the actuator (5). The cutout (6) is shaped like the shape of the actuator (5). The movable parts (2 and 3) can move closer to tighten and maintain the rod (10) or move away to remove the stop (1) through the elastic member (4). The stop (1) is movable and can easily be placed and removed from the actuator (5) as needed. An actuator (5) may be a mechanical, pneumatic or hydraulic device acting on a machine or a system to modify its operation and / or its state in order to be adapted to the work to be performed.

For example, the figure 2 shows an actuator (5) on which are mounted two stops (1) according to the invention. The actuator (5) is in the form of a jack, consisting of a body (8) and a piston (9), which separates the volume of the body into two chambers isolated from each other . A rod (10) is attached to the piston (9). These elements are represented in broken lines on the figure 2 . In the case of a hydraulic cylinder, the piston (9) and its rod (10) move under the action of a fluid in one direction or the other. The actuator (5) shown is a jack of the double acting type. Two orifices make it possible to introduce or evacuate fluid in one or the other chamber of the jack and thus to move the piston (9) in the body (8). The actuator (5) makes it possible, for example, to move parts in a mechanism and to apply pressure. The actuator (5) is mounted between two parts, one of which is caused to move relative to the other. For this purpose, a fastening system is provided on the body (8) and another on the rod (10). For the realization of the figure 2 , a fixing hole is formed in the body (8) and the rod (10) is provided with a yoke (11) provided with a bore. In the position shown, the small chamber is supplied with fluid and two stops according to the invention are placed on the rod (10). The cutout (6) of each movable part (2, 3) is advantageously shaped to the shape of the rod (10). The two stops are pressed between the body (8) and the yoke (11) of the actuator (5) via the pressure present in the small chamber of the jack.

On the figure 3 is shown an agricultural machine comprising at least one actuator (5) equipped with a stop (1) according to the invention. The agricultural machine (12) is linked to a tractor (shown partially) via a coupling device. The tractor moves the agricultural machine (12) in a direction of advance indicated by the arrow (A). In the rest of the description, the following notions "before", "back" and "front", "behind" are defined relative to the direction of advance (A). The agricultural machine (12) is shown in a working position. It consists of a frame (13) on which working members (14) are mounted. In order to adapt to the different jobs to be performed, the height of the frame (13) relative to the ground is adjustable by means of at least one actuator (5). In order to limit the downward movement, and in particular to control the maximum working depth, the actuator (5) is equipped with at least one stop (1) according to the invention. With this stop (1), it is avoided, for example, that the working members (14) penetrate too deeply into the ground. As these are removable stops and easy to assemble, the working depth can easily be adapted to the work to be done, by varying the number and / or thickness of the stops (1). In some cases, the actuators (5) are also used to lift the frame (13) and the working members (14) for transport and during turn-outs at the end of the agricultural machine (12). The large chamber of the jack is for that fed. It is therefore important that the pre-setting performed for the job is retained.

For example, the figure 3 is a seed drill for planting seeds in the soil and the working members (14) are sowing members (18). To ensure optimal seed placement in the soil, setting the sowing depth is a crucial step. Depth is defined by the sown species, seed bed quality, soil type and climatic conditions. The choice of depth is also conditioned by the pressure with which the sowing organs rest on the ground to ensure good seed germination and uniform seed emergence. The setting range for sowing depth varies depending on the species between 0 and 15 cm. The seed drill (12) also comprises a hopper (17) serving as a seed tank and a metering device (not shown). The sowing members (18) are distributed in two rows substantially perpendicular to the direction of advance (A). Each sowing member (18) is mounted on the frame (13) by means of a deformable parallelogram which allows it to move parallel to the ground. Depending on the type of drill (12), it can be equipped with tillage tools (21) placed in front of the sowing members (18). Tillage tools (21) are also to be considered as working members (14).

According to a variant not shown, the agricultural machine (12) is a working machine or soil preparation and the working members are made in the form of teeth or discs. With such devices, the working depth must also be adjusted via one or more stops (1) and be retained during use.

According to an important characteristic of the invention, the cutout (6) of at least one of the movable parts (2, 3) has a succession of surfaces (15) of circular section of different radii (R1, Rn) and the radius one of the surfaces (15) corresponds to half the diameter of the rod (10) of the actuator (5). With a surface (15) of circular section adapted to the diameter of the rod (10), the stop (1) via the movable parts (2, 3) can be reliably maintained on the actuator (5). There is no relative movement between the moving parts (2, 3) and the rod (10) and therefore the risk of disengagement of the stop (1) is eliminated. Thanks to the succession of surfaces (15), a stop (1) may be compatible with several rod diameters (10). The same abutment (1) can therefore be used to limit the stroke of an actuator (5) reliably on rods (10) of different diameters. The contact between the cutout (6) of the abutment (1) and the rod (10) is surface at one of the surfaces (15) which corresponds to the diameter of the rod (10).

According to another important characteristic of the invention, the surfaces (15) of circular section of different radii (R1, Rn) are separated by a respective edge (16). These edges (16) can be seen on the cutout (6) of the movable part (2) on the figure 1 . With these edges (16), the surfaces (15) of different radii (R1, Rn) are not tangent to each other. The surface contact between the cutout (6) and the rod (10) is on the entire surface of circular section whose radius corresponds to the diameter of the rod (10).

The succession of surfaces (15) is such that the rays are arranged decreasingly from one end of the blank (6). Preferably, the surface (15) of circular section with the smallest radius (R1) is located near the middle of the cutout (6) and the surface (15) of circular section with the largest radius (Rn) is located near the ends of the blank (6). On the stop (1) shown in figure 1 , the cut (6) of the movable part (2) has two successions of four surfaces (15) of circular section of different radii (R1, R2, R3, Rn). The surface disposed in the middle of the blank (6) being common to the two successions of surfaces (15). This common surface has the smallest radius (R1) and the large radius surface (Rn) extends respectively to both ends of the blank (6).

The figure 4 is a projection on a plane of a stop (1) according to the invention mounted on a rod (10) of circular section with a small diameter (d). For a good support of the stop (1) on the rod (10), it is essential that the moving parts (2 and 3) are not in direct contact. The cutout (6) of each movable part (2, 3) also has a circular section. The movable part (2) and the other mobile part (3) thus extend on either side of a longitudinal plane (19) passing through the center of the rod (10) and the center of rotation of the elastic member (4). The position of the stop (1) around the rod (10) does not matter. It is the access to the elastic member (4) which will position the stop (1).

On this figure 4 the moving parts (2 and 3) are symmetrical with respect to the longitudinal plane (19). It is also noted that the cutout (6) of each movable part (2, 3) is substantially symmetrical with respect to a perpendicular plane (20). in the longitudinal plane (19). The plane (20) passes through the center of the rod (10). Thus, each cutout (6) has two successions of surfaces (15) with four different radii (R1, R2, R3, Rn). According to figure 4 the diameter (d) of the rod (10) corresponds to the radius (R2). Thus, when the abutment (1) is mounted on the rod (10), the cutout (6) of each movable portion (2, 3) is shaped to establish two surface contacts separated from each other around the rod (10). The surface contacts are made on the whole surface of circular section of radius (R2). Maintaining the stop (1) on the rod (10) is thus achieved by four surface contacts. These surface contacts are distributed around the rod (10) symmetrically with respect to the longitudinal plane (19) and the plane (20) perpendicular to the longitudinal plane (19). The contacts are separated from each other. With such surface contacts, the mounting of the stop (1) is stable.

The figure 5 is an alternative embodiment of a stop (1A) according to the invention. The stop (1A) is mounted on a rod (10A) of larger diameter (D). This stop (1A) is comparable to that described above unlike the cutouts (6A, 6B) of the movable parts (2, 3). The cut (6A) of the movable part (2) comprises two successions of only three surfaces (15) of circular section of different radii (R1, R2, Rn). The cut (6B) of the other moving part (3) has a single radius. The cuts of this abutment (1A) are therefore not symmetrical with respect to the longitudinal plane (19). Note that the diameter (D) of the rod (10A) corresponds to the radius (Rn) of the cutout (6A) of the movable portion (2) and that the radius of the cutout (6B) also corresponds to the radius (Rn) . The cut (6A) of the movable portion (2) is shaped to establish two surface contacts separated from each other around the rod (10A). The surface contacts are made on the whole surface of circular section of radius (Rn). The cutout (6B) is, for its part, shaped to establish a single surface contact on the rod (10A), corresponding to the entire surface of the cutout (6B). Maintaining the stop (1A) on the rod (10) is also stable since there are three surface contacts. These three contacts are distributed around the rod (10A), the contacts are separated from each other.

According to another variant not shown, the stop is mounted on a rod whose diameter of the rod does not correspond to the cutting radius of the other part mobile. The contact between the cutout of the other moving part and the rod is therefore of the linear type. The cutting of the movable part (2) is comparable to that of Figures 4 and 5 . In this case, there are two surface contacts between the cut of the moving part (2), since the radius of one of the surfaces (15) corresponds to that of the rod and a linear contact. These contacts being also distributed around the rod, the stop is maintained in a more or less stable manner on the actuator.

It is obvious that the invention is not limited to the embodiments described above and shown in the accompanying drawings. Modifications remain possible, in particular as regards the constitution or the number of the various elements or by substitution of technical equivalents, without departing from the scope of protection as defined by the following claims.

Claims (10)

Stopper (1, 1A) for an actuator (5) comprising two movable parts (2, 3) connected by an elastic member (4) adapted to be mounted on a rod (10, 10A) to limit the stroke of the actuator (5). ), each movable part (2, 3) having a cutout (6) shaped to the shape of the rod (10, 10A), characterized in that the cutout (6) of one of the moving parts (2, 3) has a succession of surfaces (15) of circular section of different radii (R1, Rn) and that the radius of one of the surfaces (15) corresponds to half the diameter of the rod (10, 10A) of the actuator (5). Stopper according to claim 1, characterized in that said surfaces (15) of circular section of different radii (R1, Rn) are separated by a ridge (16) respectively. Stopper according to claim 1 or 2, characterized in that the surface (15) with the smallest radius (R1) is located near the middle of the cutout (6) and the surface (15) with the largest radius (Rn ) is located near the ends of the blank (6). Stopper according to any one of claims 1 to 3, characterized in that the movable parts (2, 3) extend on either side of a longitudinal plane (19) passing through the center of said rod (10). 10A) and the center of rotation of the elastic member (4). Stopper according to any one of claims 1 to 4, characterized in that the cutout (6) of one of the movable parts (2, 3) has two successions of surfaces (15) of circular section of different radii (R1, Rn), whose surface with the smallest diameter (R1) is common. Stopper according to claim 5, characterized in that the cutout (6) is substantially symmetrical with respect to a plane (20) passing through the center of the rod (10), said plane (20) is substantially perpendicular to said longitudinal plane (19). Stopper according to any one of claims 1 to 6, characterized in that the cutout (6) of each movable part (2, 3) has two successions of surfaces (15) of circular section of different radii (R1, Rn). Stopper according to claim 7, characterized in that said movable parts (2, 3) are symmetrical with respect to said longitudinal plane (19). Actuator (5) comprising at least one stop (1) according to any one of claims 1 to 8. Agricultural machine having at least one actuator (5) according to claim 9.

Images