US 5,510,685 A · Electric motor control based on conductive contact of machine component with operator for injury prevention

Abstract

A unit for controlling the operation of the electric motor is provided together with a control device, electrically connected to the body of the operator, to act on the control unit via a relay means in such a manner as to halt and reverse the rotation of the electric motor following conductive contact between the operator's body and the metal component. For receiving and supporting the feet of the operator, two conductive plates insulated from the ground are provided in such a position that the operator rests his feet via conductive shoes on them when working with the machine. The plates are connected to the control device, and the metal component is electrically connected to earth. The support plates are electrodes for the passage of low voltage electric current from one plate to the other via the body of the operator. The control device stops the motor following conductive contact between the operator's hands and the metal component.

Claims19

Dependent claims

An operator safety system for use in connection with a machine having a movably mounted metal component electrically coupled to ground and having an electric motor coupled to the component for moving said component, said system comprising:

a) a control unit coupled for controlling operation of said electric motor;
and
b) a control apparatus electrically couplable between an operator and said control unit for acting upon said control unit in response to conductive contact between the operator and said component, said control apparatus comprising:
i) two conductive members adapted for contact with respective feet of the operator;
ii) circuitry for applying to said conductive members an electrical potential;
and
iii) circuitry for monitoring electrical current flow through the operator and for causing said control unit to alter operation of said electric motor in response to a predetermined change in said monitored current.

4 more elements

An apparatus comprising:

(a) a machine having a motor, a motor controller for controlling operation of the motor, and at least one conductive component electrically coupled to ground, wherein the at least one conductive component includes a moveable component configured with the motor for movement by the motor;
(b) a conductive piece of apparel to be worn by an operator to conductively couple the operator to the at least one conductive component;
(c) a first conductive support plate for supporting and conductively coupling a first foot of the operator;
(d) a second conductive support plate for supporting and conductively coupling a second foot of the operator;
and
(e) control circuitry coupled to the first and second conductive support plates and to the motor controller,
(i) the control circuitry providing an electrical potential to one of the first and second conductive support plates such that current flows between the first foot of the operator and the second foot of the operator while the operator is supported by the first and second conductive support plates, and
(ii) the control circuitry monitoring current between the first conductive support plate and the second conductive support plate and causing the motor controller to halt or reverse operation of the motor when the operator becomes conductively coupled to one of the at least one conductive component by the conductive piece of apparel.

5 more elements

Dependencies are inferred from the claim text.

Electric motor control based on conductive contact of machine component with operator for injury prevention

Life of this patent

Electric motor control based on conductive contact of machine component with operator for injury prevention

Life of this patent

Abstract

Claims19