Pressure source for pressure device

A pressure source for a pressure device, comprising:

• a pump for pumping fluid,
• an electric motor for driving the pump,
• a pressure tank connected to said pump and to a pressure device,
• a relay coil and a relay switch for controlling power supply to the electric motor in an ON-OFF manner,
• a pressure detecting means for detecting the fluid pressure in said pressure tank and capable of outputting an electrical signal which is variable dependent on a change in said fluid pressure, and
• a controller for controlling the operation of said pump in an ON-OFF manner on the basis of a result of detection by said pressure detecting means,
• wherein said pressure detecting means comprises a first pressure detector capable of detecting a first low pressure and a first high pressure higher than said first low pressure, and a second pressure detector capable of detecting a second low pressure lower than said first low pressure and a second high pressure higher than said second low pressure, and said controller includes first and second drive signal generating circuits each capable of independently generating a drive signal for determining the ON-OFF operation of the pump, said first pressure detector being connected to said first drive signal generating circuit, and said second pressure detector being connected to said second drive signal generating circuit, said first and second drive signal generating circuits being connected to said relay coil in parallel to each other, and wherein control means is provided for controlling the operation of said first drive signal generating circuit based on signals from said first and second pressure detectors, said second pressure detector feeding its signal to the second drive signal generating circuit independently of the control by said control means.

A pressure source for a pressure device, comprising:

• a pump for pumping fluid;
• a pressure tank connected to said pump and to a pressure device;
• a pressure detecting means for detecting the fluid pressure in said pressure tank and capable of outputting an electrical signal which is variable dependent on a change in said fluid pressure;
• and
• a controller for controlling the operation of said pump in an ON-OFF manner on the basis of a result of detection by said pressure detecting means, wherein
• said controller includes first and second drive signal generating circuits each capable of independently generating a drive signal for determining the ON-OFF operation of said pump, and a judging circuit which is connected to at least said pressure detecting means, said judging circuit judges whether the pump is required to be driven or not and to determine a time duration in which the pump is driven, said judging circuit being connected to said first drive signal generating circuit and controlling the operation of the first drive signal generating circuit based at least on the signal from said pressure detecting means, and said pressure detecting means being connected to said second drive signal generating circuit and feeding its signal to the second drive signal generating circuit independently of the control by said judging circuit.