Pressure responsive linear motor driven pump

Claim 2

Pumping apparatus comprising a liquid pump including an electric linear motor, and a reciprocable member communicating with a fluid output port and driven for reciprocating motion by the linear motor to deflate/inflate a fluid space in which a non-compressible liquid is contained; pressure detecting means for detecting a pressure at the fluid output port; energization means for alternately energizing the coil to the positive/negative polarity; current detecting means for detecting the current which passes through the coil; and current control means for defining the current levels which are used by the energization means to energize the coil to the positive/negative polarity, the current control means operating such that at least during one of the energization to the positive/negative polarity, it integrates the current detected by the current detecting means until an integrated current valve reaches a given value, whereupon the polarity of energization is reversed, the current control means also operating such that during at least one of the energization to the positive/negative polarity, the energization means is caused to increase the current level which is used to energize the coil to a given value gradually, and the gradual increase is interruped whenever the pressure detected by the pressure detecting means has gone out of a given range in the process of the gradual increase.

Claim 3

Pumping apparatus according to claim 1 in which the current control means calculates a resistance of the coil based on the voltage applied across the coil and the current detected by the current detecting means, the control means correcting the integrated current value in a manner corresponding to the ratio of the resistance to a standard value.

Claim 4

Pumping apparatus according to claim 1 in which the energization means comprises positive switching means for energizing the coil to the positive polarity, negative switching means for energizing the coil to the negative polarity, timing signal generating means for generating a positive on command signal with a given short period and for generating a negative on command signal at a positive on interval indicated by a positive on interval information after the occurrence of the positive on command signal, and means responsive to the positive on command signal to turn the positive switching means on and to turn the negative switching means off and also responsive to the negative on command signal to turn the positive switching means off and to turn the negative switching means on, the current control means delivering the positive on interval information which specifies the current level to be used for the energization to the positive polarity to the timing signal generating means with a give long period, the control means gradually decreasing the positive on interval information when the integrated current value has reached the given value subsequent to the delivery and ceasing the gradual decrease when the pressure detected by the pressure detecting means goes out of a given range and terminating the gradual decrease when the positive on interval information has been gradually reduced to the given value.

Claim 5

Pumping apparatus comprising a liquid pump including an electric linear motor, and a reciprocable member communicating with a fluid output port and driven for reciprocating motion by the linear motor to deflate/inflate a fluid space in which a non-compressible liquid is contained; pressure detecting means for detecting a pressure at the fluid output port; current detecting means for detecting a current which passes through the coil; positive switching means for energizing the coil to the positive porality; negative switching means for energizing the coil to the negative polarity; timing signal generating means for generating a positive on command signal with a given short period and for generating a negative on command signal at a positive on interval indicated by positive on interval information after the occurrence of the positive on command signal; means responsive to the positive on command signal to turn the positive switching means on and to turn the negative switching means off and also responsive to the negative on command signal to turn the positive switching means off and to turn the negative switching means on; and current control means for delivering the positive on interval information which specifies the current level used to energize the coil to the positive polarity to the timing signal generating means with a given long period, for integrating the current value detected by the current detecting means since the delivery until the integrated value reaches a given value, whereupon it initiates a gradual decrease of the positive on interval information, for ceasing the gradual decrease whenever the pressure detected by the pressure detecting means goes out of a given range, and for terminating the gradual decrease when the positive on interval information has been gradually reduced to a given value.

Claim 6

Pumping apparatus comprising a liquid pump including an electric linear motor, and a reciprocable member communicating with a fluid output port and driven for reciprocating motion by the linear motor to deflate/inflate a fluid space in which a non-compressible liquid is contained; pressure detecting means for detecting a pressure at the fluid output port; current detecting means for detecting a current which passes through the coil; positive switching means for energizing the coil to the positive porality; negative switching means for energizing the coil to the negative polarity; timing signal generating means for generating a positive on command signal with a given short period and for generating a negative on command signal at a positive on interval indicated by positive on interval information after the occurrence of the positive on command signal; means responsive to the positive on command signal to turn the positive switching means on and to turn the negative switching means off and also responsive to the negative on command signal to turn the positive switching means off and to turn the negative switching means on; and current control means for delivering the positive on interval information which specifies the current level used to energize the coil to the positive polarity to the timing signal generating means with a given long period, for integrating the current value detected by the current detecting means since the delivery until the integrated value reaches a given value, whereupon it initiates a gradual decrease of the positive on interval information, for ceasing the gradual decrease whenever the pressure detected by the pressure detecting means goes out of a given range, and for terminating the gradual decrease when the positive on interval information has been gradually reduced to a given value.

Claim 7

Pumping apparatus according to claim 4 in which the current control means calculates a resistance of the coil based on the voltage applied across the coil and the current detected by the current detecting means, and corrects the current which is to be integrated in a manner corresponding to the ratio of the resistance to a standard value.

Claim 8

Pumping apparatus according to claim 4 in which the liquid which is contained in the fluid space is silicone oil.

Claim 9

Pumping apparatus comprising a liquid pump including an electric linear motor, and a reciprocable member communicating with a fluid output port and driven for reciprocating motion by the linear motor to deflate/inflate a fluid space in which a non-compressible liquid is contained; pressure detecting means for detecting a pressure at the fluid output port; energization means for alternately energizing the coil to the positive/negative polarity including positive switching means for energizing the coil to the positive polarity, negative switching means for energizing the coil to the negative polarity, timing signal generating means for generating a positive on command signal with a given short period and for generating a negative on command signal at a positive on interval indicated by a positive on interval information after the occurrence of the positive on command signal, and means responsive to the positive on command signal to turn the positive switching means on and to turn the negative switching means off and also responsive to the negative on command signal to turn the positive switching means off and to turn the negative switching means on; and current control means for defining the current level at which the energization means energizes the coil to the positive/negative polarity, the control means operating in a manner such that during at least one of the energization to the positive/negative polarity, the energization means gradually increases the current level which is used to energize the coil to a given value, and to interrupt the gradual increase whenever the pressure detected by the pressure detecting means goes out of a given range in the process of gradually increasing the current level; the current control means delivering the positive on interval information which specifies the current level to be used for the energization to the positive polarity to the timing signal generating means with a given long period, the control means gradually decreasing the positive on interval information after the reciprocable member has forwardly moved through a given stroke subsequent to the delivery and ceasing the gradual increase when the pressure detected by the pressure detecting means goes out of a given range and for terminating the gradual increase when the positive on interval information has been gradually reduced to the given value.

Claim 10

Pumping apparatus comprising a liquid pump including an electric linear motor, and a reciprocable member communicating with a fluid output port and driven for reciprocating motion by the linear motor to deflate/inflate a fluid space in which a non-compressible liquid is contained; pressure detecting means for detecting a pressure at the fluid output port; energization means for alternately energizing the coil to the positive/negative polarity including positive switching means for energizing the coil to the positive polarity, negative switching means for energizing the coil to the negative polarity, timing signal generating means for generating a positive on command signal with a given short period and for generating a negative on command signal at a positive on interval indicated by a positive on interval information after the occurrence of the positive on command signal, and means responsive to the positive on command signal to turn the positive switching means on and to turn the negative switching means off and also responsive to the negative on command signal to turn the positive switching means off and to turn the negative switching means on; and current control means for defining the current level at which the energization means energizes the coil to the positive/negative polarity, the control means operating in a manner such that during at least one of the energization to the positive/negative polarity, the energization means gradually increases the current level which is used to energize the coil to a given value, and to interrupt the gradual increase whenever the pressure detected by the pressure detecting means goes out of a given range in the process of gradually increasing the current level; the current control means delivering the positive on interval information which specifies the current level to be used for the energization to the positive polarity to the timing signal generating means with a given long period, the control means gradually decreasing the positive on interval information after the reciprocable member has forwardly moved through a given stroke subsequent to the delivery and ceasing the gradual increase when the pressure detected by the pressure detecting means goes out of a given range and for terminating the gradual increase when the positive on interval information has been gradually reduced to the given value.