CN2569952Y

CN2569952Y - Speed control device of hand-held electric tool

Info

Publication number: CN2569952Y
Application number: CN 02227231
Authority: CN
Inventors: 林显明
Original assignee: Dongguan Changyi Electric Appliance Co ltd
Current assignee: Dongguan Changyi Electric Appliance Co ltd
Priority date: 2002-04-30
Filing date: 2002-04-30
Publication date: 2003-09-03
Anticipated expiration: 2012-04-30

Abstract

The utility model relates to the technical field of the control, particularly a speed control device for electric tools such as electric drills, etc. The utility model comprises a variable resistor unit, wherein, the variable resistor unit is composed of a plurality of resistance elements which are connected in series and a manual type sliding member which is contacted with the variable resistor units and can adjust an effective resistance value of the variable resistor unit; the variable resistance part comprises a row of contact surfaces which are separated from each other, and each contact surface is electrically connected with one resistance element and a plurality of resistance elements respectively; the sliding member is provided with two separate contacts, the contacts slide correspondingly and are contacted with the different contact surfaces when the sliding member slides, and the two separate contacts can be contacted with the two contiguous contact surfaces simultaneously; thereby, the sliding member can be ensured that the sliding member can be electrically connected with at least one contact surface in the whole speed-adjusting process. The utility model has the advantages of simple structure and compact structure, and the speed of the electric tool can be controlled continuously and accurately when the utility model is used.

Description

A kind of speed control unit of hand held electric tool

Technical field:

The utility model relates to the control technology field, refers in particular to the speed control unit of a kind of electric tool such as electric drill etc.

Background technology:

The operating rate of electric tool is generally regulated by the user, common being seen speed control is to realize by the variable resistance that is arranged in the circuit, and variable resistance changes resistance value by the slip of the slide head on the carbon film that directly is attached on the printed circuit board (PCB).Yet, slide head slides on carbon film continually, unless adopt special structure, otherwise, frictional force between slide head and the carbon film is damaged variable-resistance carbon film easily, inaccuracy or instability thereby the speed control that causes electric tool becomes, and the variable resistance of employing special construction, its price is comparatively expensive again.

Summary of the invention:

The purpose of this utility model provides a kind of speed control unit that can reduce above-mentioned unfavorable factor with regard to being at the deficiencies in the prior art part.

The technical solution of the utility model is: it comprises: a variable resistance unit, this variable resistance unit is made up of the resistive element of several series connection and contacted and regulated the effective resistance value of variable resistance unit with resistive element type hand slide unit, the variable resistance part branch comprises row contact-making surface separated from one another, each contact-making surface is electrically connected with one or more resistive elements respectively, slide unit has the contact of two separation, the contact of these two separation is arranged by this way: when slide unit slides, the also corresponding slip of its contact and with the contact of different contact-making surface, the contact of these two separation can contact with two adjacent contact-making surfaces simultaneously, thereby guarantees that slide unit can be electrically connected with at least one contact-making surface in the whole process that speed is regulated.

There is a bow strip of being made by conductive material on the border of each contact-making surface, and these bow strips are parallel to each other and spend angles with the moving direction of slide unit into about 45, and the line of two contacts of slide unit then becomes 90 jiaos angle with the moving direction of slide unit.

Each contact-making surface is a bow strip of being made by conductive material, and these bow strips have different width on its bearing of trend so that have identical column pitch between each contact-making surface.

The utility model can also comprise an integrated circuit by charging of resistor unit control capacitance and discharge.

The utility model is simple in structure, compact, can reach the purpose of electric tool being carried out continuous and accurate speed control.

Description of drawings:

Accompanying drawing 1 is the side view that is provided with the electric drill of speed control unit

Accompanying drawing 2 is the enlarged drawing of the speed control unit shown in the accompanying drawing 1

Accompanying drawing 3A is the circuit theory diagrams (slide unit is in the first operating position place) of the speed control unit shown in the accompanying drawing 2

Accompanying drawing 3B is the wiring diagram of the control circuit shown in the accompanying drawing 3A on printed circuit board (PCB)

Accompanying drawing 4A for the circuit theory diagrams (slide unit is in the second operating position place) of the corresponding speed control unit of accompanying drawing 3A

Accompanying drawing 4B is the wiring diagram of the control circuit shown in the accompanying drawing 4A on printed circuit board (PCB)

The wiring diagram of control circuit on printed circuit board (PCB) of the another kind of form of accompanying drawing 5A and accompanying drawing 5B comprises a kind of different variable resistor unit, and its slide unit is in the first and second operating position places respectively)

Accompanying drawing 6A and accompanying drawing 6B are the wiring diagram of another form control circuit on printed circuit board (PCB), comprise another kind of different variable resistor unit, and its slide unit also is in the first and second operating position places respectively

The specific embodiment:

See accompanying drawing 1, shown in 2, its expression be a kind of pistol shape electric drill 10 that can embody the present utility model principle with speed control unit, this electric drill 10 is made up of body 11 and handgrip 12, the motor that drives the chuck rotation is installed in the handgrip 12, the battery tray (not shown) that can charge also is set, speed control unit 20 includes matrix 21 and a trigger 22 and a control stick 23 that stretches out from electric drill body 11 bottoms that is arranged on handgrip 12 tops, the effect of trigger 22 is rotating speeds of opening of control motor and pass and governor motor, and the effect of control stick 23 then is a rotation direction of selecting motor.

See shown in accompanying drawing 3A and the accompanying drawing 3B, be provided with control circuit 30 in the speed control unit 20, this control circuit 30 is by power supply, an integrated circuit block IC1, one variable resistance unit VR1, and the MOSFET type FET TR1 of energy amplification together, all be arranged on the printed circuit board (PCB) 40 with upper-part, the drain electrode of FET TR1 links to each other with motor.The increase of motor speed or reduce the ratio decision of opening and closing the duration by FET TR1, FET TR1 opens and closes control signal control by the output of integrated circuit block IC1 tripod.

Variable resistance unit VR1 is made of eight resistive element R1～R8 that connect mutually, the intermediate node of these eight resistive element R1～R8 is connected with bow strip X1～X7 on the circuit board 40 respectively, bow strip X1～X7 forms the contact-making surface (seeing shown in the accompanying drawing 3B) that row separate, the moving direction of contact surface X1～X7 and slide unit 31 is about 45 angles, and slide unit 31 two ends have a pair of contact that separates 32 and 33 respectively.

Trigger 22 have one be connected with slide unit 31, in order to the effective resistance value of regulating variable resistance unit VR1 and the afterbody 24 that changes motor rotary speed, it should be noted, contact 32 is two parts separately, so that at any time, slide unit 31 can both be electrically connected with the contact-making surface of at least one X1～X7 in the speed adjustment process, and this point can be found out from accompanying drawing 3B and 4B.In accompanying drawing 3B, contact 32 contacts with bow strip or contact-making surface X6 simultaneously, in accompanying drawing 4B, contact 32 contacts with X6 with contact-making surface X5 respectively, that is to say, slide unit 31 is electric bridges between contact-making surface X5 and the X6, in accompanying drawing 4B, the part of contact 32 is before disengaging with contact-making surface X6, its another part contacts with contact-making surface X5, so just can guarantee slide unit 31 in the whole process of speed control all the time with contact-making surface X1～X7 in a maintenance electrically contact, trigger 22 is in the position and ejects body 11 by spring stopping motor, at this moment, contact 32 disengages with contact-making surface X1～X7, motor will keep inactive state, and when pressing trigger 22, thereby slide unit 31 will move and be electrically connected the speed that correspondingly increases motor with bow strip X1～X7.

Resistive element R1 links to each other with the 7th pin of integrated circuit block IC1 with D2 through diode D1 with R8, between resistance R 8 and diode D1, also be provided with a current-limiting resistance R9, be connected with capacitor C 1 between integrated circuit block IC1 and the ground, between the 7th pin of positive source and integrated circuit block IC1, be provided with resistance R 10, integrated circuit block IC1 periodically discharges and recharges capacitor C 1, operating position (seeing accompanying drawing 3A and 3B) at slide unit 31, the 6th pin of integrated circuit block IC1 contacts with contact-making surface X6, therefore, variable resistance unit VR1 is divided into two parts up and down, the top resistance value is by R7 and R8 sum, the bottom is then by resistance R 1～R6 sum, in each charge cycle, electric current flows out from positive source, via resistance R 10, diode D2 and bottom resistance R 1～R6 are to capacitor C 2, and in each discharge process, electric current is from capacitor C 2 process resistance R 7 and R8, resistance R 9, diode D1, and the 7th pin of integrated circuit block IC1 flows out.The charging and discharge cycle can by change above-mentioned current path effective resistance value change, in other words, realize by mobile slide unit 31.

Accompanying drawing 5A and accompanying drawing 5B and accompanying drawing 6A and accompanying drawing 6B have shown the contact-making surface arrangement of resistor unit VR1 different in several, and its slide unit 31 lays respectively at the first and second operating position places.Under each situation, the contact of slide unit 31 contact sites 32 can both contact with the contact-making surface of at least one resistive element at any time.Identical with the embodiment shown in accompanying drawing 3A and accompanying drawing 3B and accompanying drawing 4A and the accompanying drawing 4B is: though the contact-making surface of each resistive element is not consistent, but has predetermined width between each contact-making surface, motor rotating speed can change by the effective resistance value that changes variable resistance unit VR1, and this change is step by step, discontinuous phenomenon can not occur.

Claims

1. the speed control unit of a hand held electric tool, comprise: a variable resistance unit, this variable resistance unit is made up of the resistive element of several series connection and contacted and regulated the effective resistance value of variable resistance unit with resistive element type hand slide unit, the variable resistance part branch comprises row contact-making surface separated from one another, each contact-making surface is electrically connected with one or more resistive elements respectively, slide unit has the contact of two separation, the contact of these two separation is arranged by this way: when slide unit slides, the also corresponding slip of its contact and with the contact of different contact-making surface, the contact of these two separation can contact with two adjacent contact-making surfaces simultaneously, thereby guarantees that slide unit can be electrically connected with at least one contact-making surface in the whole process that speed is regulated.

2. the speed control unit of a kind of hand held electric tool according to claim 1, it is characterized in that: there is a bow strip of being made by conductive material on the border of each contact-making surface, these bow strips are parallel to each other and spend angles with the moving direction of slide unit into about 45, and the line of two contacts of slide unit then becomes 90 jiaos angle with the moving direction of slide unit.

3. the speed control unit of a kind of hand held electric tool according to claim 1, it is characterized in that: each contact-making surface is a bow strip of being made by conductive material, and these bow strips have different width on its bearing of trend so that have identical column pitch between each contact-making surface.

4. according to the speed control unit of described any hand held electric tool of claim 1 to 3, it is characterized in that: also comprise an integrated circuit by charging of resistor unit control capacitance and discharge.