A portable electric tool, such as, for example, shears or secateurs suitable for pruning and/or harvesting work, comprises at least one moving working component disposed at the front and of a hollow frame one part of which forms the handle of the tool and inside which are housed an electric motor and a speed reducer. The outlet of the speed reducer is connected to the moving working component by means of a transmission system which comprises a moving gear unit. The tool also includes a trigger which protrudes outside the frame and operates an electric control device. The trigger and the electric control device are connected to the moving gear unit of the moving working component and follow the movements of the component. The trigger and the control device can occupy different relative positions, so that each movement made by the trigger from a neutral position, activates the control device, which in turn starts the electric motor to move the whole unit: i.e. the moving gear unit, the trigger, and the control device which then returns automatically to the neutral position at which the trigger is immobilized either by the limit stops, or manually.
This application is a continuation of application Ser. No. 07/187,176, filed Apr. 28, 1988, now abandoned. motor to cause the blade to return to its open position, usually by means of a spring.
The main disadvantage of this type of electric secateurs is that it is not possible to synchronise the speed and range of movement of the moving blade with the speed and range of movement of the control unit. Thus, depression and release of the push button causes the blades to open and close abruptly, there being little control over the operation.
Apart from the fact that this lack of control is dangerous because of the inherent inability to control the moving blade as it moves towards the fixed blade when the push-button control is depressed, it is, furthermore, a considerable disadvantage in that it is practically impossible to stop the moving blade at a precise intermediary position. As will be appreciated, it is often necessary to regulate the gap between the blades, for example, to cut into vegetation which is relatively dense, to prevent entanglement, or to allow a branch or bough to be cut.
SUMMARY OF THE INVENTION
The present invention sets out to eliminate or at least alleviate these disadvantages and shortcomings.
One object of the invention is to synchronise the speed and range of movement of the moving blade or blades of a tool with the speed and range of movement of the control unit (trigger), thereby enabling the moving blade or blades to be arrested at any intermediary position between the maximum open and closed positions and vice-versa.
According to the present invention in one aspect, there is provided a portable electric tool comprising at least one movable working component a hollow frame which are housed an electric motor and a speed reducer connected through transmission means to the working component of the tool, the tool also including a trigger which extends to a position outside the frame and is movable to operate an electric control device connected to the transmission means whose movements the trigger and control device follow, the arrangement being such that each movement made by the trigger away from a neutral position activates the control device to cause the electric motor to return the transmission means, the trigger and the control device automatically to their neutral positions whereupon the trigger is immobilised.
According to the present invention in another aspect, there is provided a portable electric tool operable by a trigger and including a hollow frame which houses an electric motor connected through speed reduction means and transmission means to a working component of the tool, the tool including a control device operable by the trigger to effect operation of the electric motor to return the transmission means, the trigger and the control device automatically to their neutral positions thereby to immobilise the trigger.
In a further aspect, the invention provides portable electric secateurs in which the trigger of the secateurs and an electric control device activated thereby are connected to the moving drive component of the moving working part of the tool, the movements of which they follow, and can be disposed at different relative positions, so that any movement of the trigger in either direction from any neutral position activates the control device which then starts the electric motor and sets the whole device in motion, i.e. the moving drive component, the trigger and the control unit return automatically to neutral positions when the trigger is immobilised, either manually or by the limit stop.
One advantage of the invention is that the design of the tool is improved, allowing greater precision in controlling and adjusting the speed of closure of the tool blades, directly with the trigger, so that it is possible to keep the blades in any intermediary position between the maximum open and closed positions.
In this way, a tool in accordance with the invention has the power of an electric cutting tool, but which is controlled and operated in the same way as traditional manual secateurs.
Another advantage of the invention is that the tool does not require electric or electronic limit stop systems, which simplifies its assembly and eliminates any jarring caused by such a system during closing or opening of the blades.
Another disadvantage of conventional electric secateurs lies in the fact that the drive system of the moving blade consists of a cogged device which does not allow the blades to be re-opened before they have been completely closed, so that it is very difficult to release the secateurs if the blades are caught around a branch which is too thick for them to cut.
According to the invention, this disadvantage is eliminated by a design in which the moving drive component of the moving working part of the tool is made up of the screw of a ball-screw and nut system connected to the working part, for example, by means of two connection rods.
This characteristic of the invention is advantageous for secateurs used in harvesting and/or pruning work, enabling the production of a high-powered device which is very efficient. The electric motor of the said device can run at high speed (around 7000 rpm). The moving drive component has a slight time delay which gives great variation in speeds and alloWs the direction of rotation of the motor to be changed, thus increasing the degree of automation of the device with only a small increase in the amount of energy consumed. There is also very precise control over the movement of the moving drive component, which gives a perfectly controlled cutting action.
Because of the simplicity of its design, the portable electric tool, according to the invention, is not heavy or bulky.
The present invention pertains to an automatic cutting device which can be utilized for cutting woody plant material (e.g., stem, stalk). The subject device can comprise a housing having a fixed blade attached thereto. A movable blade, pivotally connected to the fixed blade, can be attached to an activating device for movement. The activating device is preferably a pushrod activated by an electrical solenoid which produces the force necessary to push the movable blade against the fixed blade in a cutting action. A spring can be used to return the movable blade to the open position between cuts. The solenoid can be activated by a switching means which is triggered by a lever device located in close proximity to the cutting portion of the blades. In a specific embodiment, as the stem is lowered, the lever is depressed which triggers the switch to activate the solenoid. The solenoid forces the push rod to push the movable blade against the fixed blade in a single cutting action to cut the stem. The movable blade then returns to the open position via a spring means.
A portable, hydraulic prying machine is disclosed for use, for example, in prying open the doors of apartment buildings or of motor vehicles by rescue members in the event of an emergency. A motor and pump assembly, comprising an electric motor and a hydraulic pump driven thereby, is coupled to a pry assembly solely through the medium of a flexible conduit for delivery of a fluid under pressure from the pump to a hydraulic cylinder included in the pry assembly. The hydraulic cylinder on extension causes a pair of prying jaws to spread apart for forcing open the door. Being practically separate from the rest of the machine, the pry assembly is easier of handling. Additional embodiments are disclosed in which the pry assembly is replaced by other tool assemblies for other operations.
Pliers (1) have a pliers housing (2), a handle (6) which is articulated on the pliers housing (2), a pliers mouth (3) which accommodates processing elements, and a drive device, which can be operated by pivoting the handle (6), in order to drive the processing elements. An electric motor (18) is arranged in the pliers housing (2) in order to exert a further drive force on the processing elements during pivoting of the handle (6).
Pliers (1) have a pliers housing (2), a handle (6) which is articulated on the pliers housing (2), a pliers mouth (3) which accommodates processing elements, and a drive device, which can be operated by pivoting the handle (6), in order to drive the processing elements. An electric motor (18) is arranged in the pliers housing (2) in order to exert a further drive force on the processing elements during pivoting of the handle (6).
Hand held fluid operated shears comprises first and second blades. The blades are pivotally connected for movement of one relative to the other about an axis. The shears include a thumb-receiving handle and a finger-receiving handle. One of the handles is supported for pivoting about the axis independently of both blades. The other handle is fixed relative to the first blade. A fluid actuator is coupled between the fixed handle and the second blade. A fluid operated servo mechanism is controlled by the second blade and the pivoted handle to control operation of the fluid actuator to move the second blade relative to the first blade in coordination with the movement of the pivoted handle. The rate of movement of the second blade decreases relative to the rate of movement of the pivoted handle as the second blade moves from an open position at an acute angle relative to the first blade to a closed position where it overlies the first blade.
