Multi-position switch for handheld electric tools

Abstract

The present invention relates to a multi-position switch for a handheld electric tool, belonging to the technical field of electric tools. The switch includes a switch component mounted on a housing and a trigger located on the switch component. The switch component has a release position and a press position, and the trigger can swing with its two ends as fulcrums. The housing is also hinged with a front rocker plate and a rear rocker plate located below the trigger. When the rear part of the trigger is pressed and swings around the front fulcrum, the rear part of the trigger directly presses down the switch component through the rear part of the rear rocker plate. When the front part of the trigger is pressed and swings around the rear fulcrum, the front part of the trigger presses down the rear part of the rear rocker plate through the front rocker plate. When the middle part of the trigger is pressed, the front and rear parts of the trigger act on the front rocker plate and the rear rocker plate respectively, causing the rear part of the rear rocker plate to press down the switch component. After adopting the present invention, no matter where the trigger is pressed, the switch component can be easily and labor-savingly operated to complete the required operation.

Description

Technical Field

[0001] The present invention relates to a push-control switch, in particular to a multi-position switch for a handheld electric tool, belonging to the technical field of electric tools. Background Art

[0002] The grip of handheld power tools such as angle impact screwdrivers and angle impact wrenches is provided with a push-type control switch. To facilitate different operations in various applications, the grip and the trigger of the control switch are usually of a certain length. U.S. Patent Application No. US8853578B discloses a power tool comprising: a housing; an elongated paddle member (i.e., a trigger) having a first end and a second end, the paddle member including an input surface, the first end being movable toward and away from the housing, and the second end being movable toward and away from the housing; a support surface disposed on the paddle member; a switch mechanism having a first position and a second position; a pivot member coupled to the housing, the paddle member being positioned a distance from the support surface such that application of a force on the input surface changes the distance between the pivot member and the support surface; a multiplier member connected to the pivot member and including a first arm, the multiplier member being configured to contact the support surface such that application of a force on the input surface causes angular displacement of the multiplier member about the pivot member, wherein when the force is applied proximate the first end of the paddle member, the angular displacement of the multiplier member causes the first arm to move the switch mechanism from the first position to the second position, and when the force is applied proximate the second end of the paddle member, the multiplier member further causes the first arm to move the switch mechanism from the first position to the second position. After adopting the technical solution of this patent, no matter whether the hand is held at the front, middle or back of the grip during operation, the required control can be achieved by pressing the trigger of the control switch, thus bringing certain convenience to the operation.

[0003] However, when using it, pressing the front or back of the trigger of the control switch feels easy and effortless, while pressing the middle of the trigger is obviously strenuous. As a result, not only the control feel is not good, but also holding the middle part for control easily makes you tired. Summary of the Invention

[0004] The purpose of the present invention is to address the problems existing in the above-mentioned prior art and to provide a multi-position switch for a handheld power tool that is easy and labor-saving no matter where the switch trigger is pressed.

[0005] In order to achieve the above objectives, the applicant conducted an in-depth analysis of the above-mentioned prior art:

[0006] like Figure 1As shown in the figure, when a pressing force F is applied at one end point A, the trigger rotates around point C, and the travel of point E of the switch is L. Pressing point A to the bottom requires a downward movement of L * (AC * BD / BC * ED). Let α be the angle between BD and ED, and β be the angle between DB and CB, then the force at point B is Fb = F * (AC / BC); the force at point E of the switch is Fe = F * COS α * COS β * (AC * BD / BC * ED).

[0007] like Figure 2 As shown, when a pressing force F is applied at the other end point C, the trigger rotates around point A, and the travel of point E of the switch is L. To press point C to the bottom, the trigger needs to move down a distance L * (AC*BD / AB*ED); let α be the angle between BD and ED, β' be the angle between DB and AB, and γ be the angle between CA and BA, then the force at point B is Fb=F*COSγ*(AC / AB); the force at point E of the switch is Fe=F*COSα*COSβ'* COSγ* (AC*BD / AB*ED).

[0008] like Figure 3 As shown in the figure, when a pressing force F is applied to the middle of the trigger, it does not rotate around points A and C, but instead moves downward at both ends simultaneously; the travel of point E of the switch is L. If it is pressed all the way down, point B needs to move downward a distance L * (BD / ED); the force on point B is Fb = F; the force on point E of the switch is Fe = F*COSα* (BD / ED).

[0009] From this analysis, it can be concluded that when applying pressing force at the two ends A or C to activate the switch, only about half of the force required when applying pressing force in the middle to activate the switch is required. Therefore, it is necessary to break through the framework of the existing technology in order to achieve the purpose of the invention.

[0010] Based on this analysis, the basic technical solution of the applicant's invention for a multi-position switch for a handheld power tool is as follows: it includes a switch member disposed in a housing and a trigger located on the switch member, the switch member having a release position and a press position, and the trigger can swing with its two ends serving as fulcrums;

[0011] The housing is further hinged with a front rocker plate and a rear rocker plate located below the trigger, the rear end of the front rocker plate being located below the front end of the rear rocker plate, and the rear end of the rear rocker plate being located above the switch member;

[0012] When the rear portion of the trigger is pressed and swings around the front fulcrum, the rear portion of the trigger directly presses down the switch member through the rear portion of the rear rocker;

[0013] When the front portion of the trigger is pressed and swings around the rear fulcrum, the front portion of the trigger causes the rear portion of the rear rocker plate to press down the switch member through the front rocker plate;

[0014] When the middle portion of the trigger is pressed, the front and rear portions of the trigger act on the front rocker plate and the rear rocker plate respectively, causing the rear portion of the rear rocker plate to press down the switch element.

[0015] Both theoretical analysis and experiments have shown that, with the technical solution of the present invention, when pressure is applied to the front and rear ends of the trigger, the force required to actuate the switch is comparable to that of the prior art. However, when pressure is applied to the center of the trigger, the force required to actuate the switch is reduced by approximately half compared to the prior art. This allows the switch to be operated effortlessly regardless of where the trigger is pressed. This demonstrates that the present invention breaks free from the limitations of the prior art by achieving its objectives through a combined lever mechanism consisting of front and rear rockers. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below with reference to the accompanying drawings.

[0017] Figure 1 Schematic diagram of force analysis of the first state of the press switch in the prior art.

[0018] Figure 2 This is a schematic diagram of force analysis of the second state of the press switch in the prior art.

[0019] Figure 3 This is a schematic diagram of force analysis of the third state of the press switch in the prior art.

[0020] Figure 4 The figure is a schematic diagram of the three-dimensional structure of an angular impact screwdriver according to an embodiment of the present invention.

[0021] Figure 5 for Figure 4 Schematic diagram of the structure in the unstressed state in the middle pressing state.

[0022] Figure 6 for Figure 4 Schematic diagram of the structure of the force state at the rear end of the trigger when it is pressed.

[0023] Figure 7 for Figure 4 Schematic diagram of the structure of the front end of the trigger being stressed during pressing.

[0024] Figure 8 for Figure 4 Schematic diagram of the structure of the middle part of the trigger under force when it is pressed. DETAILED DESCRIPTION

[0025] Example 1

[0026] The multi-position switch of the handheld power tool of this embodiment is applied to Figure 4The angle impact screwdriver shown in the figure has a housing as the grip portion, which is formed by combining left and right housings 4 and 3. A motor 6 and a push-type switch 5 are housed in the housing. A transmission head 1 is mounted at the front end with the aid of a screw 2 to drive the screwdriver head used during operation.

[0027] like Figure 5 As shown, the switch member 5, which has two positions, released to de-energize and pressed to energize, is equipped with a long trigger 11, with a front fulcrum 11.1 and a rear fulcrum 11.4 respectively constrained in corresponding front and rear slots 3.1 and 3.3 of the housing. Trigger 11 can swing around its two ends. A front rocker plate 10 and a rear rocker plate 9, located below trigger 11, are also hingedly supported on the housing via two hinge pins 8.

[0028] Extending from the inner surface of trigger 11 are front and rear convexities 11.2 and 11.3, corresponding to the front and rear portions of front and rear rocker 9, respectively. The rear portion of rear rocker 9, located above switch element 5, has front and rear concavities corresponding to rear convexity 11.3 and switch element 5, respectively. The deepest depths of these two concavities are aligned with the center of hinge pin 8 of rear rocker 9, ensuring a stable load-bearing state for rear rocker 9 and smooth movement. The rear end of front rocker 10 is located below the front end of rear rocker 9, and its lower rear end abuts the upper end of spring 7, whose lower end is restrained by housing stop 3.2. Consequently, it tends to always lean toward the front end of rear rocker 9, preventing it from loosening during operation.

[0029] When the angle impact screwdriver of this embodiment is used and the trigger is operated by holding the screwdriver at the rear of the housing, Figure 6 As shown, the rear of the trigger 11 is subjected to a pressure F, and its front fulcrum 11.1 rises to the upper limit position along the front slide groove 3.1 of the housing and becomes the swing fulcrum of the trigger 11. The rear of the trigger 11 directly presses down the front upper concave of the rear part of the rear rocker 9 through the rear lower convex 11.3, and then presses down the switch member 5 through the rear lower concave of the rear part of the rear rocker 9, thereby achieving the desired operation.

[0030] When holding the trigger at the front of the housing, Figure 7 As shown, the front part of the trigger 11 is subjected to the pressure F, and its rear fulcrum 11.4 rises to the upper limit position along the rear slide groove 3.3 of the housing and becomes the swing fulcrum of the trigger 11. The front part of the trigger 11 presses down the front part of the front rocker 10 through the front convex 11.2, and then the rear end of the front rocker 10 tilts up the front end of the rear rocker 9. As a result, the rear concave part of the rear rocker 9 presses down the switch member 5, achieving the desired operation.

[0031] When holding the trigger in the middle of the housing, Figure 8As shown, the middle part of the trigger 11 is subjected to the pressure F, and its front and rear fulcrums 11.1 and 11.4 respectively descend along the front and rear slide grooves 3.1 and 3.3 of the housing, so that the front convex 11.2 and the rear convex 11.3 of the trigger 11 act on the front part of the front rocker 10 and the rear part of the rear rocker 9 respectively, so that the rear concave part of the rear rocker 9 presses down the switch member 5 to achieve the desired operation.

[0032] The mechanical analysis of each working state of this embodiment is as follows:

[0033] Figure 6 State, point M is pressed with force F, and the rear rocker rotates around point P. The switch travel is L, and to press the switch to point M, the downward movement distance is L * (PM / PN), and the force on point N is Fn = F * (PM / PN). Figure 1 From the analysis, it can be seen that the pressing pressure F at point M is slightly smaller than the force at the corresponding position in the prior art.

[0034] Figure 7 State, point T presses the pressure F, the front rocker rotates around point Q, driving the rear rocker to rotate around point P, and the front and rear rockers contact point S. The switch travel is L, and pressing the switch to point T requires a downward movement of L * (TQ * SP / SQ * NP). The force on the switch point N is Fn = F * (TQ * SP / SQ * NP). Figure 2 From the analysis, it can be seen that the pressing pressure F at point T is slightly smaller than the force at the corresponding position in the prior art.

[0035] Figure 8 In this state, with a force F applied to the center of the trigger, the front and rear rockers simultaneously generate force components F1 and F2, where F1 + F2 = F. The switch travel is L. Pressing the switch to point M requires a downward movement of L*(PM / PN), and point T requires a downward movement of L*(TQ*SP / SQ*NP). The downward movement of the trigger to the center position is 1 / 2*(L*(TQ*SP / SQ*NP) + L*(PM / PN)). The force applied to the switch point, Fn, is F1*(TQ*SP / SQ*NP) + F2*(PM / PN). Comparison is correct. Figure 3 From the analysis, it can be seen that the pressing force F in the middle is reduced by about half of the force at the corresponding position in the prior art, and because the trigger is in contact with the front and rear rocker plates at two locations at this time, the stability is better.

[0036] The results of the comparative test are shown in the following table:

[0037]

[0038] Therefore, both theoretical analysis and experiments show that after adopting the technical solution of this embodiment, the trigger can be operated more easily, especially the operating force in the middle is significantly reduced to the same as that at the two ends, so that the power tool feels good to operate and is easier to use.

[0039] In addition to the above embodiments, the present invention may also have other implementations. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A multi-position switch for a handheld power tool, characterized by: The invention comprises a switch member disposed in a housing and a trigger located on the switch member, wherein the switch member has a release position and a press position, and the trigger can be swung with both ends serving as fulcrums; The housing is further hinged with a front rocker plate and a rear rocker plate located below the trigger, the rear end of the front rocker plate being located below the front end of the rear rocker plate, and the rear end of the rear rocker plate being located above the switch member; When the rear portion of the trigger is pressed and swings around the front fulcrum, the rear portion of the trigger directly presses down the switch member through the rear portion of the rear rocker; When the front portion of the trigger is pressed and swings around the rear fulcrum, the front portion of the trigger causes the rear portion of the rear rocker plate to press down the switch member through the front rocker plate; When the middle portion of the trigger is pressed, the front and rear portions of the trigger act on the front rocker plate and the rear rocker plate respectively, causing the rear portion of the rear rocker plate to press down the switch element.

2. The multi-position switch for a handheld power tool according to claim 1, characterized in that: The front support point and the rear support point are respectively constrained in the front sliding groove and the rear sliding groove at the corresponding positions of the shell.

3. The multi-position switch for a handheld power tool according to claim 2, characterized in that: The inner surface of the trigger extends to form a front downward convexity and a rear downward convexity corresponding to the front part of the front rocker plate and the rear part of the rear rocker plate respectively.

4. The multi-position switch for a handheld power tool according to claim 3, characterized in that: The rear portion of the rear rocker plate has a front upper concavity corresponding to the rear lower convexity.

5. The multi-position switch for a handheld power tool according to claim 4, characterized in that: The rear portion of the rear rocker plate has a rear concave corresponding to the switch element.

6. The multi-position switch for a handheld power tool according to claim 5, characterized in that: The deepest points of the front upper concave and the rear lower concave are on the same straight line as the center of the hinge pin of the rear rocker plate.

7. The multi-position switch for a handheld power tool according to claim 6, characterized in that: The lower portion of the rear end of the front rocker plate abuts against the upper end of a spring whose lower end is constrained by a limit stop of the housing.

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