HYDRAULIC IMPACT DEVICE WITH PRESSURE ACCUMULATOR

Description

[0001] The invention relates to a hydraulic impact device according to the preamble of claim 1. Such a device is known from WO2005087444.

[0002] A problem concerned with pressure accumulators of the above described type is to make the flexible membrane last for a long service life, and in order to lessen the strains on the membrane there has previously been provided a movable support which also has the function of a valve means to block off the accumulator in certain operation sequences. The movable support has been formed as a mushroom-like element with a domed head and a rod like stem, wherein the stem has served as a guide means for the support. Since, however, the accumulator suitably is located at the side of the cylinder and the guide stem has been directed perpendicularly to the cylinder the accumulator tends to increase the outer dimensions of the device undesirably.

[0003] The main object of the invention is to provide an improved hydraulic impact device wherein the pressure accumulator has a reduced lateral reach to keep down the outer dimensions of the entire impact device.

[0004] Further objects and advantages of the invention will appear from the following specification and claims.

[0005] A preferred embodiment of the invention is described below with reference to the accompanying drawing.

[0006] In the drawing

Fig. 1 shows a longitudinal section through a hydraulic impact device according to the invention.

Fig. 2 shows a fractional section of the device in Fig. 1.

[0007] The impact device illustrated in the drawing comprises a housing 10 with a cylinder 11 for guiding a hammer piston 13, and a front opening 12 with a guide sleeve 14 coaxial with the cylinder 11 for receiving a working implement 15 like a breaker tool. The device also comprises a control system for directing hydraulic fluid to the opposite ends of the cylinder 11 to reciprocate the hammer piston 12. This control system includes a directional valve 18 for distributing the hydraulic fluid to the cylinder ends and a pressure accumulator 19 for absorbing pressure peaks in the system during operation of the hammer piston 12 and return pressure energy at certain points of the piston movement.

[0008] The pressure accumulator 19 comprises a casing 17 attached to the housing 10 and defining a pressure chamber 20. The chamber 20 is divided into two compartments 20a and 20b by an elastic flexible membrane 21, whereof an outer compartment 20a is preloaded by a pressurized gas supplied via a nipple 22. The other inner compartment 20b communicates with and forms a part of the hydraulic control system of the device and communicates with the cylinder 11 via a lateral opening 23. In the compartment 20b there is provided a membrane support 24 having the purpose of protecting the membrane 21 against local strain due to pressure peaks and also to act as a valve element to control the opening 23. The membrane support 24 comprises a contact portion in the form of a disc element 26 with a convex contact surface 27 facing the membrane 21, and a spring 28 for biasing the disc element 26 against the membrane 21. The spring 28 is conical for being very compact when fully compressed at low pressure levels in the compartment 20b. The spring 28 is positively located relative to the housing and the disc element 26 by having its smaller end supported around a tubular neck portion 29 on the housing wall and its bigger end engaged in a circular recess 30 in the disc element 26. This provides for a good guidance of the disc element 26 relative to the membrane 21 and the housing 10.

[0009] By utilising the spring 28 as a guide means for the membrane supporting disc element 26 instead of having the disc element provided with an integral stem as in previous accumulator designs results in a very compact accumulator 19 which brings down the lateral dimension of the impact device. The conical shape of the spring 28 contributes to keep down the dimension of the accumulator.

Claims

1. Hydraulic impact device, comprising a housing (10) with a cylinder (11), a hammer piston (13) operating in the cylinder (11), and a control system (18,19) for directing motive hydraulic fluid to opposite ends of the cylinder (11) to reciprocate the hammer piston (13), wherein the control system (18,19) comprises a pressure accumulator (19) with a pressure chamber (20) divided by a pre-loaded flexible membrane (21), a membrane support (24) movable together with the membrane (21), and a bias spring (28) acting on the membrane support (24) in the direction of the membrane (21), said membrane support (24) comprising a membrane contact portion (26), and a guide means for guiding the contact portion (26) during the movement of the membrane (21),
characterized in that said membrane contact portion (26) comprises a disc element (26) with a convex membrane contact surface, and said guide means is formed by said bias spring (28).

2. Impact device according to claim 1, wherein said bias spring (28) is a coil spring, and said disc element (26) is formed with a concentric circular recess (30) for locating one end of said bias spring (28).

3. Impact device according to claim 2, wherein a tubular neck portion (29) is provided in the housing (10) to locate the opposite end of said bias spring (28), and a fluid communication opening (23) is provided adjacent said neck portion (29).

4. Impact device according to anyone of claims 1-3, wherein said bias spring (28) is conical and has its bigger diameter end engaging said disc element (21).

Ansprüche

1. Hydraulische Schlagvorrichtung mit einem Gehäuse (10) mit einem Zylinder (11), einem Hammerkolben (13), der in dem Zylinder (11) arbeitet, und einem Steuerungssystem (18, 19) zum Zuleiten hydraulischen Antriebsfluids zu entgegengesetzten Enden des Zylinders (11), um den Hammerkolben (13) hin und her zu bewegen, wobei das Steuerungssystem (18, 19) einen Druckspeicher (19) mit einer Druckkammer (20), die durch eine vorgespannte flexible Membran (21) unterteilt ist, eine Membranhalterung (24), die mit der Membran (21) beweglich ist, und eine Vorspannfeder (28) aufweist, die auf die Membranhalterung (24) in Richtung der Membran (21) wirkt, wobei die Membranhalterung (24) einen Membrankontaktbereich (26) und Führungsmittel zum Führen des Kontaktbereiches (26) während der Bewegung der Membran (21) besitzt, dadurch gekennzeichnet, dass der Membrankontaktbereich (26) ein Scheibenelement (26) mit einer konvexen Membrankontaktfläche aufweist und die Führungsmittel durch die Vorspannfeder (28) ausgebildet sind.

2. Schlagvorrichtung nach Anspruch 1, bei welcher die Vorspannfeder (28) eine Schraubenfeder ist und das Scheibenelement (26) mit einer konzentrischen kreisförmigen Ausnehmung (30) zum Festlegen eines Endes der Vorspannfeder (26) ausgebildet ist.

3. Schlagvorrichtung nach Anspruch 2, bei welcher ein röhrenförmiger Kragenbereich (29) in dem Gehäuse (10) vorgesehen ist, um das entgegengesetzte Ende der Vorspannfeder (28) festzulegen und nahe des Kragenbereiches (29) eine Fluiddurchtrittsöffnung (23) vorgesehen ist.

4. Schlagvorrichtung nach einem der Ansprüche 1 bis 3, bei welcher die Vorspannfeder (28) konisch ist und mit ihrem größeren Durchmesser an dem Scheibenelement (21) angreift.

Revendications

1. Dispositif à percussions hydraulique, comprenant un boîtier (10) avec un cylindre (11), un piston de marteau (13) fonctionnant dans le cylindre (11), et un système de commande (18, 19) destiné à diriger un fluide hydraulique mobile à des extrémités opposées du cylindre (11) pour animer le piston de marteau (13) d'un mouvement de va-et-vient, dans lequel le système de commande (18, 19) comprend un accumulateur hydraulique (19) avec une chambre de pression (20) divisée par une membrane flexible pré-chargée (21), un support de membrane (24) mobile conjointement avec la membrane (21), et un ressort de poussée (28) agissant sur le support de membrane (24) dans la direction de la membrane (21), ledit support de membrane (24) comprenant une partie de contact de membrane (26), et un moyen de guidage pour guider la partie de contact (26) pendant le mouvement de la membrane (21),
caractérisé en ce que ladite partie de contact de membrane (26) comprend un élément de disque (26) avec une surface de contact de membrane convexe, et ledit moyen de guidage est formé par ledit ressort de poussée (28).

2. Dispositif à percussions selon la revendication 1, dans lequel ledit ressort de poussée (28) est un ressort hélicoïdal, et ledit élément de disque (26) est formé avec un évidemment circulaire concentrique (30) pour positionner une extrémité dudit ressort de poussée (28).

3. Dispositif à percussions selon la revendication 2, dans lequel une partie de collet tubulaire (29) est prévue dans le boîtier (10) pour localiser l'extrémité opposée dudit ressort de poussée (28), et une ouverture de communication de fluide (23) est prévue de manière adjacente à ladite partie de collet (29).

4. Dispositif à percussions selon l'une quelconque des revendications 1 à 3, dans lequel ledit ressort de poussée (28) est conique et son extrémité de plus grand diamètre s'engage avec ledit élément de disque (21).

Drawing