Safety switch assembly

Details Safety switch assembly Safety switch assembly

1994-07-19

1995-11-07

Scott, J. R.

Electricity: circuit makers and breakers

Special application

Actuated concurrently with operation or use of art device

200 4304, 200 4307, 200 6166, 200333, 200573, H01H 2700

Patent

active

054649544

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a safety switch for use in stopping machinery in any emergency so as to protect the operators against an accident which may result in injury or death.
2. Background Art
In factories or any sites where machinery is in operation, various types of safety switch are used so as to stop the machinery when any emergency occurs, or when a normally shut room door is carelessly left open or when a protective cover of the machinery is carelessly left open.
For example, PCT 90/08396 Publication (laid open on Jul. 26, 1990) discloses a safety switch using a pair of locking cams that are expanded sideways in response to the entry of an actuator. Japanese patent Publication (allowed) No. 1-24332 (published on May 11, 1989) discloses a safety switch also uses locking cams that are expanded in response to entry of an actuator. A disadvantage in common with these two prior art safety switches is that the body must be large enough to allow for the expansion of the arms.
The known switches are designed to shift a movable contact point from a fixed contact point to the other fixed contact point in accordance with the entry of an actuator but the problem is that deenergization is likely to occur before the door is completely locked.


THE SUMMARY OF THE INVENTION

According to the present invention, the safety switch assembly controls a source of power for machinery in accordance with the opening (or closing of) a room door, a cover or any other means provided for protecting workers against danger. The switch assembly, compact in size, switches off the machinery when the protective door is opened or when it is left half open, wherein the movement or the position of the door is transmitted to the switch assembly through an actuator secured to the door, the actuator being shaped to a unique form which can not be shared by any other thing, thus protecting the switch assembly against mischievous or malicious operation.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a switch assembly embodying the present invention;
FIG. 2 is a plan view showing the operating block and the contact-point block of the switch assembly with the cover being removed;
FIG. 3 is a cross-sectional view taken along the line 3--3 in FIG. 2;
FIG. 4 is a cross-sectional view taken along the line 4--4 in FIG. 2;
FIG. 5 is a plan view of the contact-point block showing the internal structure thereof;
FIGS. 6(a) to 6(e) are diagrammatic views showing the interaction of the actuator and the cam plates in the switch assembly;
FIGS. 7(a) to 7(d) are diagrammatic views showing the interaction of the cam plates and a substitute actuator;
FIGS. 8(a) to 8(d) are diagrammatic views showing the interaction of the cam plates and another substitute actuator;
FIGS. 9(a) and 9(b) are diagrammatic views showing a modified version of the operating section of the switch assembly;
FIG. 10 is a plan view exemplifying the locking mechanism using a lock lever;
FIG. 11 is a vertical cross-sectional view taken along the line 11--11 in FIG. 10;
FIGS. 12(a) to 12(c) are diagrammatic views showing the interaction of the actuator and the cam plates;
FIG. 13 is a cross-sectional view showing a delay mechanism in the switch section in the contact-point block;
FIG. 14 is a perspective view showing a portion of the delay mechanism shown in FIG. 13;
FIGS. 15(a) to 15(d) are diagrammatic cross-sectional views showing the process of interaction of the delay mechanism shown in FIG. 13, when the door is closed;
FIGS. 15(a)' to 15(d)' are diagrammatic plan views respectively corresponding to FIGS. 15(a) to 15(d);
FIGS. 16(a) to 16(d) are diagrammatic cross-sectional views showing the process of interaction of the delay mechanism shown in FIG. 13, when the door is opened;
FIGS. 16(a)' to 16(d)' are diagrammatic plan views respectively corresponding to FIGS. 16(a) to 16(d);
FIG. 17 is a plan view showing another modified version of a switch section in the contact-point block;
FIG. 18 is a

REFERENCES:
patent: 4395608 (1983-07-01), Eicker et al.
patent: 4524251 (1985-06-01), Schulz
patent: 4658102 (1987-04-01), Seim et al.
patent: 4695684 (1987-09-01), Bochard et al.
patent: 4904829 (1990-02-01), Berthaud et al.
patent: 4963706 (1990-10-01), Mohtasham

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