Vibrating tamper with single control lever

Abstract: Summary The purpose of the present invention is to simplify and make safer the use of vibrating tampers (1) powered by internal combustion engines and designed for compacting clay, sand or gravel, for example in pipe trenches. This is achieved by the use of a single control lever (4) which, by means of a snap-action device, can be set to any of three fixed positions with the following functions: Position 1 - Engine ignition circuit short-circuited, fuel cock closed, fuel tank vent cock closed, throttle fully closed. Position 2 - Engine ignition circuit open, fuel tank vent open, fuel cock open, throttle control in starting/idling position. Position 3 - Engine ignition circuit open, fuel tank vent open, fuel cock open, throttle control in full-throttle position.

Description: The purpose of the present invention is to simplify and make safer the use of vibrating tampers powered by internal combustion engines, and designed for compacting clay, sand or gravel, for example in pipe trenches. Previously known vibrating tampers are equipped with a number of different operating controls, such as a fuel cock, a closable fuel tank vent cock, a throttle control and a switch for stopping the engine. These controls are usually mounted in different positions on the tool and are not always easily accessible. Ease of access is a prerequisite to the safe operation of the tamper both when using the tool and during transport. The English patent GB 1337095 is related to an improved operation of an ignition switch. To achieve simple and safe operation of a vibrating tamper, a device as in claim 1 and a method for operating a vibrating tamper with it as in claim 2 are proposed. The tool is equipped with a single control lever with three distinct snap-action positions with the following functions: Position 1 Engine off, fuel tank outlet closed and fuel tank vent opening closed Position 2 Throttle control in starting/idling position, fuel tank vent opening open and fuel tank outlet open Position 3 Throttle control in full-throttle position, fuel tank vent opening open and fuel tank outlet open. The different control lever settings are made distinct by means of a snap-action device which fixes the lever securely in the required position. This is important since the setting of an intermediate position during operation may, for example, damage the centrifugal clutch between the engine and the actual tamping mechanism. Ensuring that the fuel tank outlet is closed when transporting the compactor is important since the tool will often be carried in a random manner. Otherwise, if the fuel tank outlet is open, fuel may run into the engine oil, leading to subsequent engine failure, or leak out through the carburettor. For safety reasons, it is essential for the fuel tank vent opening to be closed when transporting the tool to prevent fuel leakage through the vent. In the event of an emergency when using the tamper, the engine can be stopped easily by moving the control lever to Position 1, in which the fuel tank outlet and the fuel tank vent opening are closed automatically. The invention will be described in further detail with the aid of the appended figures, of which Fig. 1 shows a vibrating tamper with a control lever mounted integrally on the fuel tank, Fig.2 to Fig. 4 are schematic horizontal sections showing the various positions of the control lever with the cover removed, Position I being that in which all functions are closed, Position 2 being the starting and idling position, and Position 3 being the full-load position. Fig. 5 is a schematic vertical section through the fuel tank showing the control lever in Position I and Fig. 6 is a similar schematic vertical section with the control lever in Position 2 or 3. Fig. 7 is a schematic view of the snap-action device used to fix the control lever in the various positions. Fig. 1 is a perspective view of a vibrating tamper 1 showing the control handle 3 and the internal combustion engine 2 which drives the tamper mechanism. The fuel tank is designated 5 and the control lever mounted integrally on the said fuel tank is designated 4. The cover 6 of the control lever is bolted to the fuel tank. Fig. 2 is a schematic horizontal view showing the control lever 4, which is free to turn about its pivot centre 8 and is provided with a projecting section 9 with a full-length curved slot 10 whose distance from the pivot centre 8 decreases successively. Attached to the pivot arm 12, which is free to pivot on its journal 13, the free-running pin 11 runs in the curved slot 10. The end of the engine throttle cable 14 is seated in a hole 15 on the pivot arm 12 with its sleeve attached to the plate 16. In the position shown, the engine throttle is fully closed, increasing to full throttle as the control lever is turned and the other end of the curved slot 10 is reached. The outer end of the pivot arm 12 is provided with the projection 17 which, in the position shown, actuates a microswitch 18 which short-circuits the engine ignition circuit. In the case of a diesel engine, the engine is stopped in the position shown since the throttle is fully closed. The fuel tank filler pipe is designated 19 and the internally threaded bosses 20 are provided for bolting the cover 6 of the control lever into position. Fig. 3 shows the control lever in the starting and idling position. In this position, the pivot arm 12 has been actuated by the movement of the curved slot, pulling the throttle cable into the starting/idling position, in which the projection on the pivot arm no longer operates the microswitch 18. Fig. 4 shows the control lever in the full-throttle position, which is reached when the lever has been moved to its end position, at which the pin 11 acting in the curved slot 10 has turned the pivot arm 12 so that the throttle cable 14 is pulled out to its full-throttle position. The microswitch 18 remains unactuated. Fig.5 is a schematic vertical section through the fuel tank 5 and control lever cover 6 when the control lever is in Position 1, and shows a valve spindle 21 which is held against the tank vent opening 23 by the upward force of a first spring 22 so that the shoulder 24 on the spindle and a first O-ring 25 seal the opening. The lower section of the valve spindle runs freely in a cylindrical valve sleeve without bottoming in the sleeve. The valve sleeve is provided with a collar which acts on a second spring 29 to seal the outlet opening 30 in the tank 5 by pressing a second O-ring 28 against the opening. The upper section 21 of the valve spindle runs through the tank vent opening 23 to act on a first ball 31, which is free to move in a cylindrical sleeve on the top of the tank and, in certain positions, is acted on by the underside of the control lever. The lever does not act on the first ball 31 in the position shown, with the result that both the tank outlet and vent are both closed. An air filter 26 is fitted in the control lever cover 6. Fig. 6, which is a schematic vertical section through the fuel tank 5 and control lever cover 6 when the control lever is in Position 2 or 3, shows that the chamfered surface 33 on the control lever 4 has pressed the first ball 31 downward, with the result that the valve spindle 21 has been forced downward, first opening the tank vent 23 and, when the lower end of the spindle has bottomed in the valve sleeve 27, the outlet 30 of the fuel tank 5. By making the spring 22 weaker than the spring 29, the tank vent is opened before the fuel tank outlet 30. The fuel supply line to the engine is connected to the pipe branch 34 in conventional manner. Fig. 7 is a schematic view of a ball-type snap-action device 35 which serves to fix the control lever 4 in its different positions by pressing the second ball 36 into hemispherical recesses 37 located in the control lever so as to correspond to the engine off, starting/idling and full-throttle positions. The figure shows the second ball in the starting/idling position. The invention is not limited to the embodiment described, but can also be applied to other internal combustion engine-powered machines or tools, such as vibrating compactors.

Claims: Device for controlling a combustion engine-powered vibrating tamper, characterised in that it comprises a control lever (4) which turns about a pivot centre (8), mountable on a fuel tank (5), which control lever carries a projecting section (9) provided with a full-length curved slot (10) whose radial distance to the pivot centre (8) decreases successively. A free-running pin (11) attached to the free end of a pivot arm (12) runs in the curved slot (10), the other end of the said pivot arm being supported on and being free to pivot about a journal (13) mountable on the fuel tank (5). The free end of the pivot arm (12) is provided with a projection (17) which, when the control lever (4) is in a Position 1, actuates a micro switch (18) so as to short-circuit the engine ignition circuit, and is further provided with a hole (15) for attachment of an engine throttle cable (14). The underside of the control lever (4) is provided with a chamfer (33) which, as the control lever (4) is turned, acts successively, through a first ball (31), on a spring-loaded valve spindle (21) able to pass through the fuel tank (5), the upper end of which valve spindle is provided with a shoulder (24) fitted with a first O-ring (25) which, by means of a first spring (22), seals a fuel tank vent opening (23) when the valve spindle (21) is not activated by the control lever (4). The lower section of the valve spindle (21) is free to run in a valve sleeve (27) fitted with a second O-ring (28) which, under the force of a second spring (29), is made to seal a fuel tank outlet (30). Since the valve spindle (21) does not bottom in the valve sleeve (27), situated just under the first spring (22), when it is not activated by the control lever (4), and since the first spring (22) is weaker than the second spring (29), the vent opening (23) will be opened before the fuel tank outlet (30) when the control lever (4) is moved from the Position 1 to a Position 2. The different positions of the control lever (4), the Position 1, the Position 2 and a Position 3 respectively, are fixed by means of a ball-type snap-action device (35), which presses a second ball (36) into hemispherical recesses (37) located in the control lever (4) so as to correspond with the aforementioned positions. Method for operating a vibrating tamper with a device according to claim 1, characterised in that the closeting and opening of the fuel tank outlet (30) and the vent opening (23), the operation of the engine throttle cable (14) and the actuating of the micro switch (18) is controlled by the control lever (4) by setting it to any of its three fixed positions where the Position I correspond to a short-circuited engine ignition circuit, a closed fuel tank outlet, a closed fuel tank vent opening, an engine throttle in closed position and the Position 2 to an open engine ignition circuit, an open fuel tank outlet, an open fuel tank vent opening, an engine throttle in starting/idling position and the Position 3 to an open engine ignition circuit, an open fuel tank outlet, an open fuel tank vent opening and an engine throttle in full-throttle position.

Inventors: HEDLUND GUNNAR, HEDLUND, GUNNAR
Applicants: METSO DYNAPAC AKTIEBOLAG
Application year: 2000
Main classification: E01C19
IPC codes: F02P11, E01C19, F02M37, F02D11, G05G5