Peristaltic pumps

• US 4,604,034 A
• Filed: 05/02/1984
• Issued: 08/05/1986
• Est. Priority Date: 05/03/1983
• Status: Expired due to Fees

• Current Assignee: Peritronic Medical Industries Plc
• Original Assignee: Peritronic Medical Industries Plc
• Inventors: Wheeldon, Peter G., Kent, John
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US06/606,016
• Time in Patent Office: 825 Days
• Field of Search: 604/65, 604/67, 128/DIG. 12, 417/18, 417/22, 417/53, 417/12, 417/63
• US Class Current: 417/18
• CPC Class Codes: A61M 5/172 electrical or electronic A61M5/16804, A61M5/16831 take precedence
• CPC Class Codes: G05D 7/0676 by action on flow sources G05D7/0688, G05D7/0694 take precedence
• CPC Class Codes: H02P 8/14 Arrangements for controlling speed or speed and torque H02P8/12, H02P8/22 take precedence

Abstract

Control apparatus for a stepping motor driving a peristaltic pump comprises a presettable downcounter for supplying drive pulses to the stepping motor at different repetition rates so as to regulate the speed of rotation of the motor, processing means for controlling the downcounter so that the motor is normally operated to drive the pump at a predetermined pumping rate, and a sensor for detecting indexing marks at spaced positions about the pump head, the processing means being responsive to the sensor detecting the index marks to alter the count in the downcounter so as to increase the motor speed for a predetermined number of motor steps upon detection of each index mark. After the predetermined number of steps at increased speed, the processing means resets the downcounter to its normal setting, so that the motor operates at the required pumping rate for a further predetermined number of motor steps and until detection of the next successive index mark of the head. Hence, the drive motor rotates or skips more rapidly during alternate periods corresponding to dwell periods of the peristaltic pump when reduced or no fluid flow would normally occur and, consequently, the pump delivers fluid at a more constant flow rate.

Claims

1. In a peristaltic pump which is adapted to apply a peristaltic action in a succession of peristaltic cycles to a delivery tube disposed in said pump for pumping a fluid flow through said delivery tube, and which includes rotary means arranged to be driven by stepping motor means, the improvement consisting in control apparatus adapted to reduce the dwell period in each said peristaltic cycle, during which dwell period reduced fluid flow would normally occur, thereby to achieve more uniform flow of said fluid being pumped, said control apparatus comprising:

(a) means for producing electrical timing pulses,

(b) adjustable speed pulse counting means responsive to said timing pulses and connected to provide drive pulses for said stepping motor means in response to counting predetermined trains of said timing pulses,

(c) processing means for controlling said speed pulse counting means, whereby said stepping motor means is operated at a speed which drives said pump at a predetermined pumping rate,

(d) indexing means associated with said rotary means and defining a predetermined position of said rotary means, and

(e) sensing means for detecting said indexing means,

(f) said processing means being responsive to said sensing means detecting said indexing means to adjust said speed pulse counting means to increase the speed of said stepping motor means for a predetermined skip period after which skip period said processing means is adapted to reset said speed pulse counting means to operate said stepping motor means at said speed corresponding to said predetermined pumping rate until next detection of said indexing means, whereby said processing means is adapted to regulate said speed pulse counting means alternately to provide drive pulses at repetition rates corresponding to said predetermined pumping rate and said increased skip rate.

2. The peristaltic pump claimed in claim 1, including run pulse counting means and skip pulse counting means for controlling the number of steps at which said stepping motor is operated at said alternate pumping and skip rates, said run and skip counting means being controlled by said processing means and being responsive to said drive pulses provided by said speed pulse counting means.

3. The peristaltic pump claimed in claim 2, wherein said run and skip counting means are adapted to be set upon said sensing means detecting said indexing means and to produce a signal upon completion of each skip and run cycle, said processing means detecting synchronisation between said signal and a signal produced by said sensing means detecting said indexing means to monitor correct operation of said stepping motor.

4. In a method of operating a peristaltic pump which pumps fluid through a delivery tube disposed in said pump by applying a peristaltic action to said delivery tube in a succession of peristaltic cycles, and which includes rotary means arranged to be driven by stepping motor means, the improvement which consists in controlling the operation of said stepping motor means so as to reduce the dwell period in each said peristaltic cycle, during which dwell period reduced fluid flow would normally occur, thereby to achieve more uniform flow of said fluid being pumped, and which comprises the steps of:

(a) producing electrical timing pulses,

(b) counting said timing pulses and producing drive pulses for said stepping motor means in response to counting predetermined trains of said timing pulses,

(c) providing for the control of the repetition rate of said drive pulses by adjustment of the count of timing pulses required to produce each said drive pulse,

(d) adjusting said count of said timing pulses to cause said stepping motor means to operate at a speed which drives said pump at a predetermined pumping rate,

(e) detecting indexing means associated with said rotary means and defining a predetermined position of said rotary means,

(f) adjusting said count of said timing pulses in response to detecting said indexing means to produce drive pulses at an increased repetition rate and thereby increase said speed of said stepping motor means for a predetermined skip period upon detection of said indexing means, and

(g) resetting said count after said skip period to operate said stepping motor means at said speed corresponding to said predetermined pumping rate for a predetermined pumping period and until next detection of said indexing means.

5. The method claimed in claim 4, including controlling the lengths of said skip and pumping periods by counting said drive pulses.