Hand-held electric tool

Disclosed is a hand-held electric tool, in which a main shaft (1) swings back and forth around an axis (11) to drive accessories (9) of the tool to carry out various types of operations. A swing device is provided with an eccentric element (41) capable of reducing the shock caused to a shell (7) by a connecting rod component (3). Another shell (6) is provided with a valve device (5) used for adjusting the flow of air current in different air ducts. The accessories (9) of the tool can be cooled or cleaned through the air current in one of the air ducts. The main shaft (1) is provided with an elastic support (2) used for balancing the load when an electrical motor (8) is operating. The elastic support (2) can replace a bearing in supporting the main shaft (1) swinging back and forth around the axis (11).

CROSS-REFERENCE TO RELATED APPLICATION

This application is national application of PCT/CN2016/084655, filed on Jun. 3, 2016. The contents of PCT/CN2016/084655 are all hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a hand-held electric tool, especially a hand-held electric tool with a main shaft that oscillates reciprocally around an axle center thereof to drive tool accessories for various operations.

BACKGROUND OF THE INVENTION

A hand-held electric tool with a main shaft that oscillates reciprocally around an axle center thereof to drive tool accessories for various operations has been extensively applied in a variety of fields. Such hand-held electric tool includes a housing, a motor, an oscillator device and a main shaft. Usually, the oscillator device of the electric tool has an axle center and a crank component (eccentric shaft) that is parallel to an axle center of a crank arm. A spherical bearing on the crank arm is connected with a connecting rod component (oscillating bar) through a sliding pair. Sliding friction between the crank component and the connecting rod component of the hand-held electric tool generates lots of heat to result in low mechanical efficiency. A cutter is easily heated when the hand-held electric tool cuts, especially cuts a metal material for a long time. Moreover, high temperature is transferred to the main shaft and the housing to lead to improper operation, even danger. Due to failure of a dust-proof component, the hand-held electric tool easily causes reduction of the efficiency of a bearing supporting the main shaft, even failure. Many technology improvement schemes for the electric tool are provided in this industry, but there are still some shortcomings.

SUMMARY OF THE INVENTION

The present invention aims to put forward a technical solution to overcome various shortcomings of the prior art, so as to provide a hand-held electric tool with advantages of high deficiency and energy saving, convenience and comfort, and safety and reliability.

Technical solution 1 put forward by the present invention is as follows: a hand-held electric tool, comprising a housing, a motor, an oscillator device and a main shaft, the main shaft oscillates reciprocally around an axle center thereof to drive tool accessories for various operations: wherein the oscillator device is provided with a crank component having its axle center forming an angle of no greater than 30° with an axle center of a crank arm, the axle center of the crank component, the axle center of the crank arm and the axle center of the main shaft are intersected at the same point, and an intersection angle between the axle center of the crank component and the axle center of the main shaft is fixed to 70°-110°; the oscillator device is provided with a connecting rod component connected with the main shaft, another end of the connecting rod component is rotationally connected with the crank component around the axle center of the crank arm, and the connecting rod component rotates around an axis vertical to the axle center of the main shaft and intersected with the axle center of the crank component within the scope of an angle twice as large as an intersection angle of the axle center of the crank component and the axle center of the crank arm; the oscillator device is provided with an eccentric component fixedly connected with the crank component, the eccentric component can alleviate vibration on the housing when the crank component and the connecting rod component rotate around the axle center of the crank component.

In an attempt to alleviate vibration on the housing by the crank component, one eccentric component is generally applied on the hand-held electric tool of the crank component, the axle center of which is parallel to that of the crank arm thereof, but the eccentric component cannot alleviate vibration on the shell by the connecting rod component. For the purpose of reducing rotary inertia when the connecting rod component rotates around the axle center of the main shaft, a part, that is in contact with a spherical bearing in the crank component, of the connecting rod component is designed to be light and small, and accordingly, the mechanical intensity of the connecting rod component is reduced, and the output power of the electric tool is also constrained. The patent application CN201310057785 discloses a multi-functional electric tool with an axle center intersected with an axle center of the crank arm thereof, wherein an intersection angle between the axle center of the crank component and the axle center of the main shaft is not fixed, and the oscillator device is not provided with any component for shock absorption. When the intersection angle between the axle center of the main shaft and the axle center of the crank arm is greater than 150° or less than 30°, self-locking of a movement mechanism will appear in the multi-functional electric tool; when the crank component and the connecting rod component rotate around the axle center of the crank component at a high speed, the housing vibrates greatly. Compared with the prior art, the hand-held electric tool, provided by the technical solution 1 put forward by the invention, is high in mechanical efficiency, low in housing vibration, and high in output power.

Technical solution 2 put forward by the present invention is as follows: a hand-held electric tool, comprising a housing, a motor, an oscillator device and a main shaft, the main shaft oscillates reciprocally around an axle center thereof to drive tool accessories for various operations: wherein the housing is provided with a valve device capable of selectively guiding positive pressure air current generated by rotation of blades of a motor to be discharged through different air ducts; the air ducts are spaces having air current inlets and air current outlets provided in the housing, and the positive air current discharged by one of the air ducts is guided to the corresponding tool accessory for cooling or cleaning up.

In the prior art, air current generated by rotation of blades of the motor only plays a role in cooling parts within the housing of the hand-held electric tool only. In comparison with the prior art, the hand-held electric tool, provided by the technical solution 2 put forward by the invention, repeatedly applies positive air current caused by rotation of the blades of the motor to cool or clean up the tool accessories, thereby not only avoiding safety hazards resulted from high temperature generated by the tool accessories, but also improving operation efficiency.

Technical solution 3 put forward by the present invention is as follows: a hand-held electric tool, comprising a housing, a motor, an oscillator device and a main shaft, the main shaft oscillates reciprocally around an axle center thereof to drive tool accessories for various operations: wherein the main shaft is provided with an elastic support, the elastic support is provided with an inner ring and an outer ring respectively and fixedly connected with the main shaft and the housing, the elastic support is further provided with a plurality of elastic components fixedly connected with the inner ring and the outer ring; the main shaft will receive torsional elastic force applied by the elastic support while oscillating around the axle center thereof, an angular speed is maximum when the torsional elastic force received by the main shaft is zero, and an angular speed is zero when the torsional elastic force received by the main shaft is maximum.

In the prior art, when the main shaft of the hand-held electric tool oscillates circularly around the axle center thereof to drive the tool accessories for operation, the motor load will fluctuate as the angle speed of the main shaft varies, thereby leading to reduction of the motor efficiency and shortening of life. Compared with the prior art, the hand-held electric tool, provided by the technical solution 3 put forward by the invention, can balance loads of the motor when the motor operates, so as to improve efficiency and life of the motor.

Technical solution 4 put forward by the present invention is as follows: a hand-held electric tool adopted the technical solution 1 put forward by the invention: wherein the centrifugal force, produced by the eccentric element and the crank component as a whole going around the axle center of the crank component, is equal to the force produced by the connecting rod component going around the axle center of the crank component, while its direction is in opposition.

The hand-held electric tool, provided by the technical solution 4 put forward by the invention, can make the vibration intensity of the housing as low as possible.

Technical solution 5 put forward by the present invention is as follows: a hand-held electric tool adopted the technical solution 4 put forward by the invention: wherein any cross section center of the connecting rod component perpendicular to the axle center of the crank arm is at the axle center of the crank arm; when the connecting rod component, the crank component and the eccentric element move as a whole, its barycenter locates on the axle center of the crank component.

The hand-held electric tool, provided by the technical solution 5 put forward by the invention, can easily measure the moment of inertia of the connecting rod component going around the axle center of the crank, which makes it easier to design electric tools and lowers the manufacturing cost of spare part.

Technical solution 6 put forward by the present invention is as follows: a hand-held electric tool adopted the technical solution 1 put forward by the invention: wherein the connecting rod component is provided with an elastic element and connected with the main shaft fixedly; the elastic element around an axle that is perpendicular to the axle center of the main shaft and intersects with the axle center of the crank component can produce bending deformation bigger than the intersection angle between the axle center of the crank component and that of the crank arm; the elastic element around the axle center of the main shaft cannot produce bending deformation bigger than the intersection angle between the axle center of the crank component and that of the crank arm.

The hand-held electric tool, provided by the technical solution 6 put forward by the invention, can diminish the influence made by the machining tolerance and the assembly error and reduce the noise caused by flexible connection.

Technical solution 7 put forward by the present invention is as follows: a hand-held electric tool adopted the technical solution 6 put forward by the invention: wherein the angle of intersection between the axle center of the crank component and that of crank arm is no more than 5°; the main shaft is provided with elastic support; the elastic support is provided with inner ring and outer ring fixedly connected with the main shaft and the housing separately ; the elastic support is also provided with several elastic elements, which fixedly connect the inner ring and the outer ring; when the main shaft oscillates around the axle center, the elastic support will exert torsion spring on the main shaft; when the axle centers of the crank component, the crank arm and the main shaft are on the same plane, the torsion spring exerted by the elastic support on the main shaft is zero.

The hand-held electric tool, provided by the technical solution 7 put forward by the invention, not only can diminish the influence made by the machining tolerance and the assembly error to the electrical tool, reduce the noise caused by flexible connection and extend the service life of bearings, but also maintain the balance on the load of the motor. Therefore, the efficiency of the motor can be enhanced.

Technical solution 8 put forward by the present invention is as follows: a hand-held electric tool adopted the technical solution 2 put forward by the invention: wherein the valve system is provided with a control valve; the control valve is provided with a diversion port, docking with the airflow inlet; the adjustment of the relative position between the diversion port and the airflow inlet can help adjust the airflow of the airflow outlet.

The hand-held electric tool, provided by the technical solution 8 put forward by the invention, can cool or clean accessories of the tool by conveniently using fan blades of the motor.

Technical solution 9 put forward by the present invention is as follows: a hand-held electric tool adopted the technical solution 2 put forward by the invention: wherein the housing is provided with diversion element that can adjust the direction and the diversion element is provided with an airflow outlet of accessories of the tool, to which the direction of airflow is over against.

The hand-held electric tool, provided by the technical solution 9 put forward by the invention, can cool or clean accessories of the tool by conveniently using fan blades of the motor.

Technical solution 10 put forward by the present invention is as follows: a hand-held electric tool adopted the technical solution 10 put forward by the invention: wherein in place of the bearing, the elastic support sustains the main shaft that goes around the axle center to oscillate back and forth.

The hand-held electric tool, provided by the technical solution 10 put forward by the invention, can diminish the harmful influence made by the failure of dustproof elements to the electrical tool, and also it can slow down the vibration of the housing caused by the main shaft suffering from the radial impact.

Among hand-held electric tools provided by the technical solution 1 put forward by the invention, the angle of intersection between the axle center of the crank component and that of the main shaft is fixed as 90°, which would be the most optimal.

Among hand-held electric tools provided by the technical solutions 7 and 10 put forward by the invention, the elastic support can be unibody or assembled by using many spare parts. The elastic element can be made from metal material or other elastic materials.

Above all, it is achievable to provide a hand-held electric tool featuring high-efficiency, energy-saving, convenient, comfortable, safe and reliable through adopting one or more technical solutions put forward by the present invention.

The numbered list of the relevant elements and technical features is as following:

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention is further illustrated in combination with drawings and the preferred embodiment:

A crank component4having its axle center45forming an angle of 2° with the axle center44of the crank arm is provided for the preferred embodiment. The axle center45of crank component4, the axle center44of crank arm and the axle center11of main shaft1intersect at a same point, and the intersection angle between the axle center45of crank component4and the axle center11of main shaft1is fixed at 90°. A connecting rod component3connecting with the main shaft1is provided as well. The other end of the connecting rod component3is rotatably connected with the crank component4around the axle center44via a bearing42. The connecting rod component3can turn within a range not smaller than 4° around an axis which is perpendicular to the axle center11and intersects with the axle center45. The crank component4is provided with a bearing43which is rotatably connected with a housing6, the crank component4is securely connected with a motor shaft83at a same axle center in the meantime, and the housing6is securely connected with a housing7. When the motor8drives the crank component4to rotate continuously, the connecting rod component3drives the main shaft1to swing around the axle center11within a range of 4°.

In the preferred embodiment, an eccentric element41is provided integrally with the crank component4. The connecting rod component3has a symmetrical shape with the center lying on the axle center44, and the centroid of the moving whole consisted of the connecting rod component3, the crank component4and the eccentric element41is lain on the axle center45. The centrifugal force generated by a rotating connecting rod component3around the axle center45is equal to and has a contrary direction with that generated by the crank component4with the eccentric element41, bringing a milder vibration to the housing7.

In the preferred embodiment, the connecting rod component3is provided with an elastic component31which is a sheet metal body. When the connecting rod component3rotates around the axle center45, the elastic component31can generate a bending deformation greater than 2° around an axis which is perpendicular to the axle center11and intersects with the axle center45, and the bending deformation of the elastic component31around the axle center11is small enough to be ignored. Noise produced by the movable connection can be avoided through the secure connection between the connecting rod component3and the main shaft1via the elastic component31, and the elastic component31can generate an adaptive elastic deformation due to the motion dislocation of the component, thereby reducing the adverse effects caused by machining tolerance and assembly error.

In the preferred embodiment, the main shaft1is provided with an elastic support2. The elastic support2is provided with an inner ring22and an outer ring23which are respectively securely connected with the main shaft1and the housing7, and is provided with4elastic components21which are securely connected with the inner ring22and the outer ring23as well. When the axle center45of crank component4, the axle center44of crank arm and the axle center11of main shaft1lie in a same plane, no elastic deformation of the elastic components21is generated in the transverse direction of the main shaft1. When the main shaft1swings back and forth around the axle center11, the elastic components21will generate bending deformation and tensile deformation in the transverse direction of the axle center11, and the main shaft1will be subject to the torsional elasticity imposed by the elastic support2. The angular velocity is the maximum when the torsional elasticity imposed on the main shaft1is zero, and the angular velocity is zero when the main shaft1is subject to a maximum torsional elasticity. During operation, the load of motor8is directly proportional to the torsional elasticity imposed on the main shaft1and to the angular velocity of the main shaft1, such that the elastic support2can balance the load of the motor8. When the main shaft1is subjected to a radial external force, a slight displacement of the axle center11with respect to the housing6will occur, and the vibration caused can be buffered. With adopting the elastic support2as the support of the main shaft1instead of a bearing, the noise produced by the movable connection, as well as the adverse consequences caused by the bearing grease failure due to the scraper seal failure, can be avoided.

In the preferred embodiment, the housing6is provided with airflow inlets61and62, an elastomer seal63and a regulating valve5, and the regulating valve5is provided with diversion ports51and52which are respectively butted with the airflow inlets61and62. A diversion element71and an airflow outlet72are provided on the housing7, and an airflow outlet711is provided on the diversion element71. The diversion element71can adjust angle around the axle center11to face the airflow outlet711directly to the tool accessory9.

In this preferred embodiment, following effects can be achieved by adjusting the angle of the regulating valve5around the axle center45: The diversion port51and the airflow inlet61are connected while the diversion port52and the airflow inlet62are closed, then the positive pressure airflow82produced by the rotating fan blade81of the motor8is vented through the airflow outlet711, and the airflow outlet711directly faces the tool accessory9, such that the tool accessory9can be cooled or cleaned; the diversion port51and the airflow inlet61are closed while the diversion port52and the airflow inlet62are connected, then the positive pressure airflow82produced by the rotating fan blade81of the motor8is vented through the airflow outlet72; the diversion port51and the airflow inlet61together with the diversion port52and the airflow inlet62are connected, then the positive pressure airflow82produced by the rotating fan blade81of the motor8is respectively vented through the airflow outlets711and72; in order to ensure the effective cooling of the motor8, the diversion port51and the airflow inlet61will not be closed simultaneously with the diversion port52and the airflow inlet62.

There can be multiple alternatives to some technical features of the preferred embodiment: As shown inFIG. 5, the crank component4is integrated with the motor shaft83, the eccentric element41is securely connected on the crank component4, and the connecting rod component3is integrally molded with elastic material. Similar alternatives have no substantial influence on the implementation effect of this embodiment.

The detailed description and drawings are merely illustrative of the invention, rather than limiting the scope of the invention being defined by appended claims and equivalent thereof. A person skilled in the art can make nonessential changes to some technical features based on the technical proposals put forward in the invention, so as to obtain other embodiments.