Vibro-isolation of connections of structural units of hand tools

Abstract: The vibro-isolation of connections of structural units of hand tools consists of a vibro-isolator with a constant reaction force. On the side of a body (3) of a compressed-­ air engine an upper (9) and a lower (10) elastic guide is provided as a first stage of vibro-isolation in directions (x, y) perpendicular to the axis of symmetry of the tool. In the main direction (z) parallel to the axis of symmetry of the tool vibro-isolation is ensured by an elastic system consisting of a vibro-isolator (1) with a constant reaction force connected to the body (3) of the compressed-air engine through a spring washer (2). On the side of a grip (14) a vibro-isolator (1) with a constant reaction force is mounted through a spring washer (6) and sleve (7) acting as a second stage of vibro-isolation of the grip (14). Moreover, the second stage of vibro-isolation for the left hand of an operator is the grip itself in the form of a spring sleeve (13) screwed onto the end-portion of the body-housing (8). The vibro-isolation of an air-supply system includes an intermediate sleeve (17) and a silent-block connection of a supply unit (15) with the grip (14).

Description: The invention relates to a compressed-air driven hand tool comprising a body-housing, a compressed air engine disposed within the body-housing, means for introducing compressed air in the air engine, a grip for holding the tool with one hand, a sleeve screwed onto the end portion of the body-housing for holding the tool with the other hand and a constant interaction force vibro-isolator. Such a compressed-air driven hand tool is known from the DE-A-1 018 819. This tool comprises an air engine which is guided in the body-housing, the air engine and the body housing being in contact with each other. Thus, vibrations in a plane substantially perpendicular to the elongation of the body housing which are caused by the motion the air engine are directly transferred to the body-housing. Since a damping is also not provided between the body-housing and the grip and the sleeve at the end of the body-housing, respectively, the vibrations are transferred to the hands of the user of the tool. But also vibrations in the direction of elongation of the body-housing are not sufficiently damped. An inner cylinder of the air engine is connected to an elastic disk by means of a cap, the outer edge of the disk being connected with the grip and the body-housing, respectively. However, the rubber disk only serves for reaction supressing of the movement of the air engine. The elastic disk is not designed to prevent vibrations. PL-B-115 O85, 118 242, or 122 477 disclose hand tools with a pneumatic drive and vibro-isolations, which are limited to one direction of vibrations only, that is in the direction of the elongation of the body-housing, in which maximum vibration acceleration levels are observed. The existance of vibrations with a value exceeding the permissible ones in the directions perpendicular to the main axis of symmetry of the tool are not considered. PL-B-122 477 describes a pneumatic hammer with a shock absorber. The hammer has at least two bolts, corresponding springs slidably mounted on an annular barrel extension, a seat, an immovable elastic ring, mounted with the external dimension in the hammer seat and with the internal dimension in the barrel, as well as a flanged sleeve with a barrel slidably mounted in it. The bolts passing through the said elastic ring connect on one side the seat and on the other side the sleeve by means of nuts, springs and a flange of the above mentioned sleeve. However, such a vibro-isolation is not sufficient with regard to existing vibration standards. The problem underlying the invention is to provide a compressed-air driven hand tool with low vibrations on the tool grips during the operation thereof. According to the invention, this problem is solved in that the sleeve is elastic and elastic guides are disposed between the body housing and upper and lower portions, respectively, of the air engine. The elastic guides provide a vibro-isolation between the body-housing and the air engine and allow a reciprocating motion of the air engine relative to the body-housing. The constant interaction force vibro-isolator is connected to the air engine by means of a spring washer there-between and to the grip by means of a spring washer and a sleeve between the grip and the constant interaction force vibro-isolator, whereby a vibro-isolation between the grip and the air engine for air engine vibrations in the direction of elongation of the body-housing is provided. Finally the means for introducing compressed air to the air engine comprises an intermediate sleeve mounted in the air engine and a silent block connection of a supply unit with the grip. Preferably the upper guide comprise a silent-block pressed into a seat in the body-housing and a sleeve on the inner side of the silent block, the sleeve consisting of a material having a low friction-coefficient. It is convenient that the lower guide comprises a silent block pressed into the body-housing and a sleeve provided at the inner side of the silent block and having a hole with internal splines acting as an additional vibro-isolation for a torsional vibration of the air engine. The provision of elastic guides allows relative reciprocating motions of the engine body in the housing. The lower guide acts additionally as a vibro-isolator for limiting the torsional vibration which can be generated by the operation of the compressed-air engine. Owing to the described vibroisolation system a considerable reduction of the vibration levels of the grips for the operator's hands in all the three directions is obtained. An embodiment of the invention is further explained with the aid of a drawing, wherein Fig. 1 presents diagrammatically the vibro-isolation of a compressed-air driven hand tool and Fig. 2 is the section A-A shown in Fig. 1. The vibro-isolation of the connections of structural units of the hand tool is effected for the three various directions x, y and z of the Cartesian ccordinate system. For acting in the direction z, which is the direction of elongation of the tool, there are provided a constant interaction force vibro-isolator 1 which is separated by a spring washer 2 from the body of a compressed-air engine 3, as well as by spring washer-sleeves 4 for complete vibro-isolation of a guide 5 of the vibro-isolator 1. On the side of a grip 14 spring washers 6 and sleeves 7 are fixed. The vibro-isolation between a body-housing 8 and the compressed-air engine 3 is ensured by elastic guides 9 and 10. The upper guide 9 is a sleeve 11 made of plastic material with a low friction coefficient and a considerable damping coefficient which is mounted in an elastic connector 12 made of rubber. The lower guide 10 is a connection of a silent-block type, which serves as a vibro-isolation for the directions x, y and z and for torsional vibration. The lower guide 10 has a sleeve 18 with a shaped splined slidable connection with the compressed-air engine 3 which enables torques to be transmitted from the body-housing 8 to the compressed-air engine 3. The guides 9 and 10 represent a first stage of a vibro-isolation on the way from the compressed-air engine 3 to the grip means for the operator's hands. A second stage of vibro-isolation for the left hand of an operator comprises an elastic sleeve 13 made of a material with a considerable coefficient of friction and screwed onto the body-housing 8 by means of a spring embedded in the elastic sleeve 13. For the right hand of the operator the grip 14 is provided, a spring washer 6 and an elastic sleeve 7 acting as a second stage of vibro-isolation. Moreover, a two-stage vibroisolation for an air supply system is provided. A first vibro-isolation stage includes an intermediate sleeve 17 made of a material with a considerable damping coefficient mounted in the compressed-air engine 3. A second stage of vibro-isolation comprises an elastic sleeve 16 by means of which an air supply tube is mounted elastically in the tool grip 14.

Claims: A compressed-air driven hand tool comprising a body-housing (8), a compressed air engine (3) disposed within the body-housing (8), means (16, 17) for introducing compressed air in the air engine (3), a grip (14) for holding the tool with one hand, a sleeve (13) screwed onto the end portion of the body-housing (8) for holding the tool with the other hand and a constant interaction force vibro-isolator (1) characterised in that the sleeve (13) is elastic, elastic guides (9, 10) are disposed between the body housing (8) and upper and lower portions, respectively, of the air engine (3), the elastic guides (9, 10) providing a vibro-isolation between the body-housing (8) and the air engine (3) and allowing a reciprocating motion of the air engine (3) relative to the body-housing (8), the constant interaction force vibro-isolator (1) is connected to the air engine (3) by means of a spring washer (2) therebetween and to the grip (14) by means of a spring washer (6) and a sleeve (7) between the grip (14) and the constant interaction force vibro-isolator (1), whereby a vibro-isolation between the grip (14) and the air engine (3) for air engine vibrations in the direction of elongation of the body-housing (8) is provided, and the means for introducing compressed air to the air engine (3) comprises an intermediate sleeve (17) mounted in the air engine (3) and a silent block connection of a supply unit (15) with the grip (14). A compressed-air driven hand tool according to claim 1, characterised in that the upper guide (9) comprise a silent-block (12) pressed into a seat in the body-housing (8) and a sleeve (11) on the inner side of the silent block, the sleeve (11) consisting of a material having a low friction-coefficient. A compressed-air driven hand tool according to claim 1 or 2, characterised in that the lower guide (10) comprises a silent block pressed into the body-housing (8) and a sleeve (18) provided at the inner side of the silent block and having a hole with internal splines acting as an additional vibro-isolation for a torsional vibration of the air engine (3).

Inventors: CEMPEL CZESLAW, DOBRY MARIAN WITALIS, GARBATOWSKI WIESLAW, CEMPEL, CZESLAW, DOBRY, MARIAN WITALIS, GARBATOWSKI, WIESLAW
Applicants: POLITECHNIKA POZNANSKA
Application year: 1989
Main classification: B25D17
IPC codes: B25D17, B25D9