CN2093435U

CN2093435U - Limit switch

Info

Publication number: CN2093435U
Application number: CN 91201203
Authority: CN
Inventors: 李国宁
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-01-20
Filing date: 1991-01-20
Publication date: 1992-01-15

Abstract

The utility model provides a revolving arm type limit microswitch which has higher sensitivity, higher repeated accuracy and larger overall angle of rotation. The utility model uses a more reasonable cam to obtain the functions on the basis of the existing limit switch. The cam is characterized in that the cam is provided with four vertices, wherein the connecting line of two adjacent vertices is in parallel with the connecting line of other two adjacent vertices; the length of the connecting line of the first two vertices is longer than that of the original two vertices. The utility model can meet the need of the present machine tool industry and meet the engineering machinery, transmission belt and other rough movement mechanical needs.

Description

Limit switch

The utility model discloses a kind of medium speed's of being applicable to pivoted arm limit switch, uses such as lathe both be applicable to, being applicable to the limit switch of uses such as engineering machinery again, is a kind of pivoted arm, cam, cam resetting device of comprising exactly, the limit switch of switch core operating mechanism and switch core.

Engineering machinery such as concreting machinery, the industry elevator, conveyer belt etc., say that generally motion is all lower, be that the line of motion sexual deviation can reach 5～15 millimeters, even it is bigger, perhaps transmitting thing promptly uses as collision block, therefore employed pivoted arm limit switch is except that should having suitable action sensitivity and repeatable accuracy, also should be able to adapt to the smart rough situation of collision block action, installation requirement also should suitably relax, and promptly limit switch should have less " action corner " and bigger " overtravel corner " and " total travel corner ", less " action is depressed " arranged in other words, and bigger " overtravel is depressed " reaches " under the total head "." the action corner " of existing tumbler-style micro-limit switch is less, " full corner " is also less, so though action sensitivity and repeatable accuracy are higher, but its ability that adapts to coarse movement is relatively poor, installation requirement is higher, therefore be unsuitable for uses such as engineering mechanism, industrial elevator, conveyer belt basically, with homemade typical products LX19 series and JLXK ₁The limit switch of series is an example, the pivoted arm limit switch θ in the series _Action13 °～30 ° of=± (), θ _Entirely≤ ± 45 °, when this two serial limit switch is used, often produce false operation or the pivoted arm phenomenon that fractures in engineering machinery, thereby make machinery out of control, its performance and reliability deficiency are fairly obvious.The 3SE3 series limit switch product of the West Germany Siemens Company of present domestic introduction, its relevant parameter has been improved to θ _Entirely≤ 70 °, visible main the improvement is that full corner increases to some extent, and combination property increases, but for engineering machinery, still dislikes the applicability deficiency.Comparatively ideal parameter is about θ _Action13 °～30 ° of≤± (), θ _Entirely≤ ± 90 °, coarse for a large amount of motion beyond the machine industry, by the low many occasions of dress precision, the applicability of existing tumbler-style micro-limit switch and reliability obviously can't satisfy.

Cause the reason of the above-mentioned disadvantage of existing tumbler-style micro-limit switch, be that the cam face design of existing switch is improper, when causing big corner, cam can't normally automatically reset.Its cam cross section is a rectangle or arc in the prior art; accompanying drawing 1 provides the shape and the working condition of existing rectangular cam; wherein Fig. 1 (A) is the home position; 1 is cam returning spring among the figure; 2 are the cam Ding Rod that resets; 3 is cam; 4 are actuating Ding Rod, and 5 are overtravel protection spring, and 6 is the switch core; part 1; 2 form the cam resetting device, and part 4,5 is formed switch core operating mechanism; 0 is the cam rotation center; pivoted arm and cam directly are fixedly connected, and part 1 spring force is made much biggerly than part 5 spring forces, and also the reset force than switch core self is multiple many greatly; therefore can think that spring force and moment that switch core and operating mechanism thereof act on the cam can ignore, and only need consider that the cam resetting device is to action of cam power and moment.Fig. 1 (B) is the situation of cam when rotating under the outside force effect.By Fig. 1 (B) as seen when cam (3) rotates, the arm of force that resets of cam (3) is ao ', this value increases with cam angle and diminishes gradually, when cam forwards extreme position to, the arm of force ao ' that resets is quite little, though still have cam returning spring power to exist, reseting torque can't make the cam reposition, sees Fig. 1 (c).By Fig. 1 (c) as seen, the ultimate angle of cam (being the issuable hard-over of pivoted arm) is the arc-tangent value of cam length-width ratio, so θ _{The utmost point}＜90 °, what talk here also only is perfect condition, and in fact owing to the influence of foozle and frictional force, the actual full corner of switch can not reach aforesaid extreme position.By as can be known aforementioned, the ultimate angle that desire improves cam can adopt ways such as increasing the cam length-width ratio to realize, but in fact owing to be subjected to the restriction of factors such as volume, structure, technology, price, the full corner of the limit switch that is increased is very limited in this way.Fig. 1 (D) is the shape of existing arc cam, and this arc cam also has similar disadvantage.

The purpose of this utility model is to overcome the existing in prior technology disadvantage, and a kind of have higher working sensitivity and repeatable accuracy are provided, and the limit switch of more complete works of corner is arranged again simultaneously, satisfies the needs of every profession and trade technological progress with higher combination property.

The utility model is to comprise pivoted arm, the cam resetting means, insert in the system of compositions such as shape core operating mechanism and switch core and improve the back cam, this cam can reappear the advantages such as high sensitivity of existing shape under the outside force effect, can under bigger corner, make simultaneously the reset arm of force and the moment of cam enough big, specifically its cam cross section has following feature: four summit a are arranged on the cam, b, c, d, connect straight line and the straight line parallel that is connected between two other summit between two adjacent vertex, and connect two straight lengths between the summit greater than the length that connects the straight line between other two summits.

Adopt cam resetting means when the home position of this shape to contact into stability with two summits of cam, when cam rotates under pivoted arm drives, cam always is with resetting means and contacts, form the unstable equilibrium state, its reseting torque always points to reset condition, and when cam angle reaches 90 °, return moment again and still enough point to the home position greatly and still, produce the function of big corner self-return thus.

As a kind of embodiment of the present utility model, the cross section of the cam of limit switch is one trapezoidal or for trapezoidal surely.

As another kind of embodiment of the present utility model, the cross section of limit switch arcly cuts two formed shapes in base angle for half garden shape cuts two base angles or.

As the most preferred embodiment of above-mentioned two kinds of forms of implementation, the base angle of cam should be 45 °～80 °.

Fall with the angle, garden on four summits that facts have proved cam, and the limit switch that is become has best performance.

If the cam rotation axis is shifted out the centre of form outside of cam or shift out outside the cam section, its full corner will be bigger.

Advantage of the present utility model is:

1. be provided with mechanism, better handled various influencing factors with advanced suitable exercise relation.Therefore, have complete works of corner, highly sensitive, the little contour combination property of high accuracy and volume, parameter is all near theoretical optimal value.

2. the utility model can carry out under existing working condition, and product has higher technology inheritance, so have good popularization condition.

Accompanying drawing 2,3,4,5,6,7 provides the cam face among embodiment of the present utility model and the different embodiment, and wherein Fig. 5 (A) is as Figure of abstract.

Accompanying drawing 2 is example structure figure of the present utility model, and wherein Fig. 2 (A) is a front view, and Fig. 2 (B) is a vertical view.

The be as the criterion cam of trapezoid cross section of accompanying drawing 3, the schematic diagram of operating mechanism and resetting device.

Accompanying drawing 4 is half garden shape (or arc) and the cam that cuts two base angles.

Accompanying drawing 5 is the cam of another kind of accurate trapezoid cross section, the schematic diagram of operating mechanism and resetting device.

Accompanying drawing 6 all is positioned at the example of cam the same side for resetting device and operating mechanism.

Accompanying drawing 5 provides situation when adopting the trapezoidal cross-section cam rotation, this figure cam angle is ± 90 °, by Fig. 5 (C) as seen when cam angle reaches 90 °, arm of force o ' the d that resets of cam is still greater than zero, and moment is still pointed to the direction that makes the cam reposition, its value is also enough big, so cam still can normally automatically reset.By as can be known to the mechanical analysis of accompanying drawing 5, when cam is in Fig. 5 (A), act on the various power of cam and moment balance mutually, cam is in poised state.When cam rotation, the cam contact point that the top defends (2) and cam (3) that resets is (a), ao ' diminishes along with the cam rotation arm of force, and contact point changes to d by a, the arm of force becomes do ' by ao ', and do ' also with cam rotation gradual change little, but do ' is forever greater than zero, meanwhile, cam returning spring also is compressed, and in the process of whole cam rotation, the functional relation between reseting torque and cam angle is complicated, but the value of cam reseting torque is always enough big, and Hang Seng Index is to the cam direction that resets.Owing to compare in the power and the moment of cam with action of reset spring, spring counter-force and countertorque that switch core and switch core actuating Ding Rod etc. acts on the cam are very little, can ignore fully in mechanical analysis and not consider simultaneously, only need consider to exist motion.Therefore, after the outside force of pivoted arm was removed, cam promptly can be returned to the home position reliably under the effect of cam returning spring power, and switch core and operating mechanism are returned to reset condition too.If cam rotates round about, stressed and motion conditions is like above-mentioned.

Also can release as drawing a conclusion by above analysis; Arc or shape corner cut cross section, half garden cam also has identical effect.Equally, if resetting means, the correlation of operating mechanism and cam is shown in the accompanying drawing 6, and promptly the mechanical analysis during " homonymy layout type " its cam rotation is with aforementioned consistent basically.

Claims

1, a kind of limit switch, comprise pivoted arm, cam, switch core operating mechanism and cam resetting device, switch core operating mechanism and cam resetting device all contact with cam, it is characterized in that having on the cam four summits, wherein the line of two adjacent vertexs is parallel with the line of other two adjacent vertexs, and the first two summit wire length is greater than the length of back two summit lines.

2, limit switch as claimed in claim 1, the shape of cross section that it is characterized in that cam are one trapezoidal or accurate trapezoidal.

3, limit switch as claimed in claim 1 is characterized in that the cam shape of cross section is for half garden or arcly cut formed shape behind two base angles.

4, as the limit switch of claim 2 or 3, it is characterized in that base angle satisfies: α=80 °～45 °.

5, limit switch as claimed in claim 4 is characterized in that four summit a, b, the equal fillet of c, d of cam (3).

6, limit switch as claimed in claim 5 is characterized in that the rotation of cam is positioned at the centre of form or the centre of form outside of cam (3).