Mine hoist brake regulator

A hydraulic friction brake for controlling deceleration of a mine hoist comprising:

• pump means continually circulating hydraulic braking fluid through a valve means, the valve means regulating flow of hydraulic fluid to control braking pressure applied by the brake for braking the mine hoist;
• and,
• control means for controlling operation of the valve means including:
• means for sensing the speed of the hoist and providing a signal representing the speed,
• means for differentiating the speed signal to obtain a differentiated signal representing the rate of change of the speed of the mine hoist,
• means for producing a reference signal representing a predetermined hoist deceleration rate,
• means for comparing the differentiated signal with the reference signal to provide a switching output signal having a first value when the differentiated signal is greater than the reference signal and having a second value when the differentiated signal is less than the reference signal, and
• integration means responsive to the output signal to provide a first valve signal that controls the operation of the valve means, the first valve signal decreasing at a predetermined rate to correspondingly control the opening of the valve means and proportionally reduce the braking pressure of the brake when the output signal has its second value and the first valve signal remaining constant maintaining the opening of the valve means and the braking pressure of the brake constant when the output signal is at its first value.

A method of controlling a hydraulic brake to control deceleration of a mine hoist comprising the steps of:

• continually circulating hydraulic braking fluid through a valve and regulating the valve opening to control braking pressure applied by the brake for braking the mine hoist;
• and,
• controlling operation of the valve including the steps of:
• (i) sensing the speed of the hoist and providing a signal representing the speed,
• (ii) differentiating the speed signal to obtain a differentiated signal representing the rate of change of the speed of the mine hoist,
• (iii) producing a reference signal representing a predetermined hoist deceleration rate,
• (iv) comparing the differentiated signal with the reference signal to provide a switching output signal having a first value when the differentiated signal is greater than the reference signal and having a second value when the differentiated signal is less than the reference signal, and
• (v) opening the valve at a predetermined rate responsive to the second output signal being present to proportionally reduce the braking pressure of the brake and maintaining the opening of the valve constant to maintain the braking pressure constant in response to the first output signal being present.

A controller for controlling a hydraulic friction brake having a pump means continually circulating hydraulic braking fluid through a valve means where the valve means regulates flow of hydraulic fluid to control braking pressure applied by the brake for braking a mine hoist, the controller comprising:

• means for sensing the speed of the hoist and providing a signal representing the speed,
• means for differentiating the speed signal to obtain a differentiated signal representing the rate of change of the speed of the mine hoist,
• means for producing a reference signal representing a predetermined hoist deceleration rate,
• means for comparing the differentiated signal with the reference signal to provide a switching output signal having a first value when the differentiated signal is greater than the reference signal and having a second value when the differentiated signal is less than the reference signal, and
• integration means responsive to the output signal to provide a first valve signal that controls the operation of the valve means, the first valve signal decreasing at a predetermined rate to correspondingly control the opening of the valve means and proportionally reduce the braking pressure of the brake when the output signal has its second value and the first valve signal remaining constant maintaining the opening of the valve means and the braking pressure of the brake constant when the output signal is at its first value.