Variable capacity pump having a pressure responsive relief valve arrangement

A variable capacity pump comprising:

• a pumping means having an inlet port, a first outlet port, and a second outlet port, for pumping oil from said inlet port to said first outlet port and to said second outlet port;
• an oil supply passage connected uninterruptedly at one end thereof to said second outlet port of said pumping means;
• a regulator valve having a bore, pressure responsive means disposed in said bore, a pressure chamber, and a pressure admission port which is connected to said oil supply passage and in communication with said pressure chamber;
• and
• a branch passage connected to said oil supply passage;
• said regulator valve further having a relief port connected to said inlet port of said pumping means, and a transfer port connected to said first outlet port of said pumping means;
• said pressure responsive means including a spool disposed in said bore and moveable in response to pressure within said pressure chamber between a first position in which said transfer port is connected to said branch passage and a second position in which said transfer port is connected to said relief port;
• said regulator valve further having a second relief port connected to the inlet port of said pumping means and wherein said pressure responsive means includes a piston which is disposed in said bore and is moveable in response to the pressure within said pressure chamber between a first position in which fluid connection between said branch passage and said second relief port is blocked and a second position in which the fluid connection between said branch passage and said second relief port is established.