Compressed-air supply system of vibro-isolated tools

Abstract: The compressed-air supply system of vibro-isolated tools comprises a telescopic tubular connection of a grip with a compressed-air engine. A cut-off valve (1) is mounted at an inlet of a duct (3) in a housing-grip (5). The outlet of said duct (3) is connected to a pipe (4) of a supply system closed at the end and mounted in a grip-­ housing (5) by means of an elastic connection. Over the circumference of the pipe (4) of the supply system special holes (10) with increasing diameters are provided which during the motion of the housing relative to the compressed-air engine overlap with holes (9) in an inter­ mediate sleeve (8) mounted in a body (6) of the com­ pressed-air engine.

Description: This invention relates to a compressed-air supply system for vibro-isolated tools comprising a grip-housing, a compressed-air engine connected to the grip-housing by means of a telescopic tubular connection including a feeding pipe mounted in the grip-housing, openings being provided at the circumference of the feeding pipe, and a cut-off valve mounted at an inlet of a duct provided in the grip-housing, the outlet of the duct being connected to the feeding pipe. Such a compressed-air supply system for vibro-isolated tools is known from the FR-A- 1 154 429. The feeding pipe of this supply system is attached to the compressed air engine and slidably mouted in a sleeve provided in the grip-housing. Serveral openings having the same diameter are provided at the circumference of the feeding pipe. At both ends of the feeding pipe openings are provided which communicate with a feeding chamber in the grip-housing and a duct in the air engine, respectively. This solution does not eliminate the uplift pulsating pressure that is created on the feeding pipe due to changing pressures in the feeding chamber, which are caused by the reciprocating movement of the feeding pipe due to the pulsating nature of the reciprocating supply of the compressed air engine. PL-B-122 477 discloses a pneumatic hammer with an air supply system and a shock absorber, having a vibro-isolation. An intermediate sleeve of this vibro-isolation connects a body of a compresses-air engine to a grip of the tool. The intermediate sleeve is a connector between the housing of the hammer and the body and transmits the pressure force applied by an operator onto the housing and so to the body of the hammer. Vibrations of the heavily vibrating hammer body are transferred onto the housing. This hammer does not ensure a spatial vibro-isolation in the directions perpendicular to the axes of symmetry of the hammer. A pneumatic hammer known frorn the PL-B-122 381 includes an air supply system provided with two supply tubes mounted in a body-housing which coact slidably in holes in the engine body. The provision of the supply pipes which simultaneously serve as a protection against revolution is practically troublesome and can lead to jamming of the hammer in the housing. Moreover, the supply system does not eliminate low-frequency vibration of the grip produced by pulsation of air pressure in the inlet duct. The problem underlying the invention is to provide a compressed-air supply system which eliminates grip vibration produced by air pressure pulsations in a supply duct. According to the invention this problem is solved in that the feeding pipe is closed at one end and mounted in the grip-housing by means of an elastic connection, in that the diameter of the openings of the feeding pipe increases with decreasing distance from the grip-housing, and in that an intermediate sleeve is mounted in the compressed-air engine, the intermediate sleeve having apertures which align with the openings of the feeding pipe during the motion of the grip-housing relative to the compressed-air engine. In the intermediate sleeve, as well as in the body of the compressed-air engine, preferably passages are provided for relieving a space formed in the intermediate sleeve in front of the closed end of the pipe of the supply unit. It is convenient that the pipe of the supply unit is mounted in the grip-housing by means of a silent block type connection. The system according to the invention permits an infinitely variable variation of intensity of the inflowing air and exhaust of that air to the body of the compressed-air engine from the housing and simultaneously ensures freedom of motion of the engine body and elimination of the pulsating uplift pressure force produced by pressure pulsation in the supply duct. Provision of the system with a cut-off valve enables the compressed-air engine to be supplied through an opening with very low flow rate for checking the tool for proper operation. In order to reduce the friction forces in the system a special intermediate sleeve made of plastic material with a very low friction coefficient and a considerable damping coefficient is used. The described system is relatively simple and easy to make and does not deteriorate the effects of the vibro-isolation of the tool. An embodiment of the invention is further explained with the aid of a drawing, presenting diagrammatically a supply system in an axial section. The supply system comprises a supply unit which is provided with a cut-off valve 1 which is actuated by pressing slightly a valve arm 2 mounted to a grip-housing 5 of a tool partly shown in the drawing. Compressed-air flows through a duct 3 in the grip-housing 5 to a feeding pipe 4. The duct 3 includes a slidable vibro-isolating connection of the grip-housing 5 to a compressed-air engine 6. The feeding pipe 4 is mounted elastically by means of a silent-block type connection 7 with its open end in the grip-housing 5. So the feeding pipe 4 can slightly move in the directions x and y together with the vibrating compressed-air engine 6. In this way a second stage of vibro-isolation is obtained. The feeding pipe 4 coacts with an intermediate sleeve 8 mounted in the compresses-air engine 6 and is made of a material having a low friction coefficient and a considerable damping coefficient. The intermediate sleeve 8 also provides a first stage of vibro-isolation on the way from the compressed-air engine 6 to the grip-housing 5. In the side wall of the intermediate sleeve 8 apertures 9 are provided through which supply air from the feeding pipe 4 flows when the apertures 9 align with openings 10 in the feeding pipe 4. The control of the flow rate dependent from the depth of insertion of the feeding pipe 4 into the intermediate sleeve 8, which is effected by the operator using the tool. Supply air flows from the apertures 9 of the intermediate sleeve 8 to a space 12 formed between a stub pipe 11 of the compressed-air engine 6 and the intermediate sleeve 8. From the space 12 air is exhausted to a timing gear chamber slide through passages 13. A space 14 formed in the intermediate sleeve 8 in front of the closed end of the feeding pipe 4 is connected by a passage 15 to a space 16 of a vibro-isolator with a constant reaction force.

Claims: Compressed-air supply system of vibro-isolated tools comprising a grip-housing (5), a compressed-air engine (6) connected to the grip-housing (5) by means of a telescopic tubular connection including a feeding pipe (4) mounted in the grip-housing (5), openings (10) being provided at the circumference of the feeding pipe (4),and a cut-off valve (1) mounted at an inlet of a duct (3) provided in the grip-housing (5), the outlet of the duct (3) being connected to the feeding pipe (4), characterized in that the feeding pipe (4) is closed at one end and mounted in the grip-housing (5) by means of an elastic connection (7), the diameter of the openings (10) of the feeding pipe (4) increases with decreasing distance from the grip-housing (5), and an intermediate sleeve (8) is mounted in the compressed-air engine (6), the intermediate sleeve (8) having apertures (9) which align with the openings (10) of the feeding pipe (4) during the motion of the grip-housing (5) relative to the compressed-air engine (6). Supply system according to claim 1 characterized in that passages (15) are provided in the intermediate sleeve (8) and in the compressed-air engine (6) for relieving a space (14) formed in the intermediate sleeve (8) in front of the closed end of the feeding pipe (4). Supply system according to claim 1 or 2 characterized in that the feeding pipe (4) is mounted in the grip-housing (5) by means of a silent-block type connection.

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