Exhaust gas operated vacuum pump assembly

In combination, a vacuum pump assembly and an internal combustion engine which generates exhaust gases having pressure pulsations of varying pressure and amplitude at different engine speeds and with portions of the amplitude being at subatmospheric pressure at low engine speeds and with said amplitudes being wholly above atmospheric pressure at high engine speeds, said pump assembly comprising:

• a vacuum pump means for pumping air from a vacuum source and including a reciprocable pumping member movable through first and second strokes, an actuating means including a housing and a reciprocable actuating member movable through first and second strokes and which is drivingly connected to said pumping member to move the same through its first and second strokes, said actuating member dividing said housing into first and second chambers, said first chamber being in communication with the exhaust gases and said pressure pulsations during their increasing pressure phase of each amplitude causing the actuating member and pumping member to be moved through their first strokes, bleed hole means in said housing for communicating said second chamber to atmosphere, said second chamber and bleed hole means defining an air spring means for biasingly opposing movement of said actuating and pumping members through their first strokes and for effecting movement of the actuating and pumping members through their second strokes during the decreasing pressure phase of each amplitude of the pressure pulsations, said actuating member when at rest having a position spaced from one side of said bleed hole means, said exhaust gas pressure pulsations causing said actuating member to be reciprocated through strokes having a displacement such that said bleed hole means remains uncovered during low speed engine operation, through strokes having a displacement such that said bleed hole means is alternately covered and uncovered by said actuating member during medium speed operation of the engine and through strokes having a displacement wholly on the other side of said bleed hole means to at all times block communication between said second chamber and the atmosphere via said bleed hole means during high speed engine operation whereby said air spring means functions as a variable rate air spring means and said pump assembly is operable to pump said air from said vacuum source during low engine speeds and loads when portions of the amplitude of the pressure pulsations are at subatmospheric pressure and during high engine speeds when the entire amplitude of the pressure pulsations are wholly above atmospheric pressure.

In combination, a vacuum pump assembly and an internal combustion engine which generates exhaust gases having pressure pulsations of varying pressure and amplitude at different engine speeds and with portions of the amplitudes being at subatmospheric pressure at low engine speeds and with said amplitudes being wholly above atmospheric pressure at high engine speeds, said pump assembly comprising:

• double-acting pump means including a reciprocable pumping member movable through first and second strokes for pumping air from a vacuum source during each stroke, an actuating means including a housing and a reciprocable actuating member movable through first and second strokes and which is drivingly connected to said pumping member to move the same through its first and second strokes, said actuating member dividing said housing into first and second chambers, said first chamber being in communication with the exhaust gases and said pressure pulsations during their increasing pressure phase of each amplitude causing the actuating member and pumping member to be moved through their first strokes, bleed hole means in said housing for communicating said second chamber to atmosphere, said second chamber and bleed hole means defining an air spring means for biasingly opposing movement of said actuating and pumping members through their first strokes and for effecting movement of the actuating and pumping members through their second strokes during the decreasing pressure phase of each amplitude of the pressure pulsations, said actuating member when at rest having a position spaced from one side of said bleed hole means, said exhaust gas pressure pulsations causing said actuating member to be reciprocated through strokes adjacent one end of said housing and having a displacement such that said bleed hole means remains uncovered during low speed engine operation, through strokes having a displacement such that said bleed hole means is alternately covered and uncovered by said actuating member during medium speed operation of the engine and through strokes adjacent the other end of said housing and having a displacement wholly on the other side of said bleed hole means to at all times block communication between said second chamber and the atmosphere via said bleed hole means during high speed engine operation whereby said air spring means functions as a non-linear variable rate air spring means and said pump means of said pump assembly is operable to pump said air from said vacuum source during low engine speeds when portions of the amplitude of the pressure pulsations are at subatmospheric pressure and during high engine speeds when the entire amplitude of the pressure pulsations are wholly above atmospheric pressure.

In combination, a vacuum pump assembly and an internal combustion engine which generates exhaust gases having pressure pulsations of varying pressure and amplitude at different engine speeds and with portions of the amplitudes being at subatmospheric pressure at low engine speeds and with said amplitudes being wholly above atmospheric pressure at high engine speeds, said pump assembly comprising:

• a double-acting pump means including a reciprocable pumping member movable through first and second strokes for pumping air from a vacuum source during each stroke, an actuating means including a housing and a reciprocable actuating member movable through first and second linear strokes and which is drivingly connected to said pumping member to move the same through its first and second strokes, said actuating member dividing said housing into first and second chambers, said first chamber being in communication with the exhaust gases and said pressure pulsations during their increasing pressure phase of each amplitude causing the actuating member and pumping member to be moved through their first strokes, bleed hole means in said housing for communicating said second chamber to atmosphere, said bleed hole means being located in a side of said housing and extending transversely of the linear stroke movement of said actuating member, said second chamber and bleed hole means defining an air spring means for biasingly opposing movement of said actuating and pumping members through their first strokes and for effecting movement of the actuating and pumping members through their second strokes during the decreasing pressure phase of each amplitude of the pressure pulsations, said actuating member when at rest having a position spaced from one side of said bleed hole means, said exhaust gas pressure pulsations causing said actuating member and pumping member to be reciprocated through strokes adjacent one end of said housing and pump means, respectively, and the actuating member having a displacement such that said bleed hole means remains uncovered during low speed engine operation, through strokes having a displacement such that said bleed hole means in said housing is alternately covered and uncovered by said actuating member during medium speed operation of the engine and through strokes adjacent the other end of said housing and pump means and having with the actuating member a displacement wholly on the other side of said bleed hole means to at all times block communication between said second chamber and the atmosphere via said bleed hole means during high speed engine operation whereby said air spring means functions as a non-linear variable rate air spring means and said pump means of said pump assembly is operable to primarily pump air from said vacuum source adjacent said one end of the pump means during low engine speeds when portions of the amplitude of the pressure pulsations are at subatmospheric pressure and to pump air from said vacuum source adjacent the other end of the pump means during high engine speeds when the entire amplitude of the pressure pulsations are wholly above atmospheric pressure.