US 4,726,366 A · Apparatus and method for controlling lung ventilation

Abstract

A lung ventilator is provided that reduces the number of mechanical components and is able to rapidly adjust to provide a selected volume of air or other gas for delivery to a patient's lungs. The ventilator includes a brushless-type DC electric motor having a number of coils that are energized in a predetermined manner to cause reciprocating movement of a piston within a cylinder. The retracted end position of the piston in a cylinder is used to define the volume of air that is to be received by the patient. Three Hall sensors are connected to the motor at predetermined locations and sense the position of the rotor as it rotates due to the energization of the coils. Each of the pulsed outputs from the Hall sensors is out-of-phase relative to the other Hall sensor outputs. The six different binary outputs of the Hall sensors are identified so that a ROM is able to provide a predetermined output for each of the identified Hall sensor combinations inputted to the ROM. The outputs from the ROM are applied to driving transistors, the outputs of which are applied to the motor coils to cause desired rotational movements of the motor rotor. The position of the piston is monitored also using the Hall sensor outputs. The actual position of the piston is found and compared with the desired or selected position of the piston, which is based on a selected volume of gas to be sent to the patient. When the actual position of the piston corresponds to the selected position, piston movement is stopped. A reference sensor is used in determining a reference piston position from which the actual piston position can be found at any instance in time. The present invention also includes a one-piece manifold to which the cylinder is mounted. The manifold includes a number of passageways along which air is carried to the patient.

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Claims11

Dependent claims

A lung ventilating system, comprising:

motor means including a brushless-type electric motor having a number of coils;
housing means;
piston means movable relative to said housing means;
linkage means operatively connecting said motor means and said piston means;
first means for sensing movement of said motor means, wherein the position of said piston means relative to said housing means is continuously determinable during movement of said piston means using said motor means sensed movement;
second means communicating with said first means for controlling the operation of said motor means and thereby the movement of said piston means, said second means including processing means communicating with said first means, said processing means processing information received from said first means for controlling direction of movement of said piston means and for controlling activation of said motor means;
programmed memory means communicating with said first means and said processing means for providing a predetermined output for controlling the energization of said coils of said motor means, said programmed memory means also outputting a velocity-related signal relating to the speed of said motor means;
reference sensor means operatively associated with said piston means for sensing a reference position of said piston means relative to said housing means and communicating said reference position to said processing means;
speed controlling means communicating with said programmed memory means and receiving said velocity-related signal, said speed controlling means also continuously inputting a desired velocity-related signal to said programmed memory means relating to a desired speed of said motor means, said desired velocity-related signal being continuously adjusted, the amount of adjustment depending upon the magnitude of difference between said received velocity-related signal and a predetermined magnitude, said predetermined output of said programmed memory means depending on said input from said first means, said input from said processing means, and said input from said speed controlling means;
and
input means communicating with at least one of said processing means and said speed controlling means for use in controlling the speed and amount of movement of said piston means.

8 more elements

Dependencies are inferred from the claim text.

Description5,511 words

Summary1,211 words

#A Microfiche Appendix is included in this application and consists of 2 microfiche having 136 frames.

#The present invention relates to a respiratory apparatus and, in particular, to method and apparatus for controlling the volume of air, or other gas, delivered to a patient's lungs.

#Numerous techniques have been developed or advanced for controlling the volume of air or other gas to be delivered to a patient suffering from one or more respiratory deficiencies. Particularly in conjunction with portable ventilators, it is known to utilize complicated ratchet and gear mechanisms together with a brush-type electric motor for controlling the movement of a piston. The retracted position of the piston, at one end of its cycle, defines the volume of air to be provided to the user of the ventilating machine. It is common practice for the operator to be able to adjust the volume of air or gas to be delivered to a patient using such machines. Such adjustment is important so that individualized respiratory treatment is available, i.e. the volume of air and the velocity of piston movement can be controlled to achieve a desired inspiration/expiration cycle for each patient. In U.S. Pat. No. 4,141,355 to Apple, issued Feb. 27, 1979 and entitled "Apparatus For Automatic Ventilation of the Lungs", a mechanism is disclosed for changing the volume of air that can be delivered and is characterized by the use of a ratchet wheel, a sliding block, and a jack screw. These members cooperate to effect movement of a piston in order to change the volume of air that is being provided to a patient.

Brief description of the drawings8 figures

#FIG. 1 is a block diagram of the present invention;

#FIGS. 2A-2B illustrate the motor assembly and crank arm assembly of the present invention;

#FIG. 3 is a circuit diagram showing further details of the motor coils and motor driver circuit;

Detailed description4,200 words

#With reference initially to FIGS. 1 and 2A-2B, a respiratory apparatus is illustrated that includes the capability of controlling the volume of gas to be delivered to a patient. Adjustment of the volume of gas is achieved by regulating the stroke of a piston 10. The piston 10 is moved by means of a motor assembly 12, a gear box assembly 14, and a crank arm assembly 16.

#The motor assembly 12 is a brushless-type DC electric motor that includes coils 18, a rotor 20 and a stator 22. The motor 12 preferably has, as part of the stator 22, three coils 18a, 18b, 18c. The coils 18a-18c are schematically depicted in FIG. 3. In one embodiment, the rotor contains an 8-pole permanent magnet such that, as the rotor 20 rotates, the positions of the poles can be detected by a sensor assembly 24. The detection of the poles, as will be explained subsequently, is used in controlling both the speed of the motor 12 and the position of the piston 10. The rotor 20 includes a bore formed through the center thereof in order to receive an input shaft 26 for use in coupling the rotary motion of the rotor 20 to the gear box assembly 14. The stator 22 of the motor assembly 12 is concentric with the rotor 20.

#The rotational movement of the rotor 20 is coupled to the gear box assembly 14, which is illustrated in greater detail in FIG. 4, using the input shaft 26. The gear box assembly 14 includes a gear box base 34. The rotational movement of the input shaft 26 is coupled to a number of gear stages 40, 42, 44. The rotational movement of the gear stage 44 is coupled to an output gear 46 having an output shaft 48. The output shaft 48 is linked to a fixed radius crank arm 50 of the crank arm assembly 16, as seen in FIG. 2A. The motor stator 20 is fastened to the gear box assembly 14 by conventional means, such as screws.

Apparatus and method for controlling lung ventilation

Life of this patent

Apparatus and method for controlling lung ventilation

Life of this patent

Life of this patent

Abstract

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Claims11

Description5,511 words

Classification5 codes

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Description5,511 words