Fluid pump apparatus

Details Fluid pump apparatus Fluid pump apparatus

2001-05-16

2003-04-15

Freay, Charles G. (Department: 3746)

Pumps

Condition responsive control of pump drive motor

By control of electric or magnetic drive motor

C417S366000, C417S423700, C417S423120, C604S151000, C415S900000

Reexamination Certificate

active

06547530

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to fluid pump apparatus and more specifically to those for use for example for artificial hearts, employing a magnetic bearing to magnetically levitate an impeller to deliver fluid such as blood.
2. Description of the Background Art
FIG. 15
is a vertical cross section of one example of a body of a blood pump as one example of a conventional fluid pump apparatus. In
FIG. 15
, the pump body includes a cylindrical housing
1
internally partitioned axially by partitions
11
,
12
,
13
and
14
to accommodate an electromagnet unit
20
, a pump unit
30
and a motor unit
40
. Electromagnet unit
20
has an electromagnet
21
and a magnetic bearing sensor
22
incorporated therein. Casing
1
has on the electromagnet unit
20
side (or one side) a side wall having a center provided with an inlet
15
introducing blood. At least three electromagnets
21
and at least three magnetic bearing sensors
22
surround inlet
15
circumferentially. Electromagnets
21
and magnetic bearing sensors
22
are attached to an internal wall surface of partition
11
externally isolating electromagnet unit
20
.
In pump unit
30
an impeller
31
is rotatably housed and it has a portion closer to electromagnet unit
20
that is supported by electromagnet unit
21
contactless through partition
12
, and magnetic bearing sensor
22
senses the distance between magnetic bearing sensor
22
and one side of impeller
31
. Impeller
31
has the other side with a plurality of permanent magnets
32
buried therein circumferentially.
Motor unit
40
houses a motor stator
41
and motor rotor
42
. Motor stator
41
is arranged on an external peripheral surface of a cylindrical member
43
extending cylindrically from an internal wall surface of partition
14
externally partitioning motor unit
40
. Motor rotor
42
rotates around a shaft supported by an internal peripheral surface of cylindrical member
43
via a motor bearing
44
provided in the form of a ball or roller bearing. Motor rotor
42
has an inner peripheral surface provided with a permanent magnet
47
facing an electromagnet
46
of motor stator
41
and motor rotor
42
rotates through their magnetic force, borne by motor bearing
44
. Motor rotor
42
has a surface facing pump unit
30
and having a plurality of permanent magnets
45
buried therein circumferentially, opposite to permanent magnet
32
buried in impeller
31
, through partition
13
.
In the blood pump apparatus thus configured, magnetic bearing sensor
22
provides an output which is referred to by a controller
10
, described hereinafter, to control a current flowing to electromagnet
21
, to control an attractive force provided by electromagnet
21
toward the opposite side of impeller
31
.
Furthermore impeller
31
has a portion closer to motor unit
40
that is affected by the attractive force introduced by permanent magnets
32
and
45
. And impeller
31
is magnetically levitated by a non-controlled bearing provided by permanent magnets
32
and
45
and a controlled bearing provided by electromagnet
21
. Impeller
31
is rotated by a driving force of motor unit
40
and blood introduced through inlet
15
is output through an outlet (not shown) formed at pump unit
30
.
In the
FIG. 15
fluid pump apparatus, electromagnet
21
generates heat attributed to a current flowing to magnetically levitate impeller
31
and motor stator
41
generates heat attributed to a current flowing to rotate motor rotor
42
. Furthermore, motor bearing
44
is provided for example in the form of a ball or roller bearing and generates heat through friction as motor rotor
42
rotates. Furthermore, to externally release the heat generated by electromagnet
21
, electromagnet
21
and magnetic bearing sensor
22
are fixed on an internal wall surface of partition
11
provided in contact with an outside of casing
1
, and motor stator
41
is also provided at an internal wall surface of partition
14
provided in contact with an outside of casing
1
, at an external peripheral surface of cylindrical member
43
. Thus casing
1
is increased in temperature by the heat generated by electromagnet
21
and motor stator
41
.
When the heat increases temperature, the heat is transferred to magnetic bearing sensor
22
and the sensor consequently has a temperature drift, which disadvantageously results in unreliable sensing.
Furthermore if fluid pump apparatus in
FIG. 15
is used for example as a blood pump and thus configures a portion of an artificial heart and implanted in a human body the heat generated as described above may have a negatively effect on the tissues of the human body. This needs to be addressed by an approach taken separately. Such approaches to be taken, however, would increase the blood pump in size. Thus it is impossible to reduce the blood pump for the artificial heart in size or weight.
FIG. 16
is a block diagram showing a controller driving the conventional fluid pump apparatus shown in FIG.
15
.
In
FIG. 16
, controller
10
includes a sequence circuit
101
externally receiving a control signal corresponding to commands for rotation, levitation and the like, an AC-DC converter
102
receiving an AC power supply, and a monitor circuit
103
monitoring the blood pump's operation and externally communicating the condition. AC-DC converter
102
converts an AC voltage to a DC voltage which is in turn applied to a motor power amplifier
104
, a magnetic bearing power amplifier
124
and a DC-DC converter
105
. DC-DC converter
105
stabilizes the DC voltage and supplies it to a circuit as described hereinafter.
Controller
10
also includes a sensor circuit
110
having a carrier wave generation circuit
111
, a tuning circuit
112
and an amplifier
113
incorporated therein. Carrier wave generation circuit
111
generates a carrier wave which is in turn provided via a connector
150
to magnetic bearing sensor
22
housed in housing
1
of the pump body. Magnetic bearing sensor
22
, as shown in
FIG. 15
, outputs a signal having an amplitude corresponding to a distance between magnetic bearing sensor
22
and impeller
31
. Tuning circuit
112
is tuned in to the signal to extract a detection signal, amplifier
113
amplifies the detection signal and provides it to magnetic bearing control circuit
121
.
A magnetic bearing control circuit
121
receives the detection signal, responsively provides PID control, and feeds the control output to a magnetic bearing PWM circuit
122
. Magnetic bearing PWM circuit
122
uses pulse width modulation (PWM) to vary the received control signal in pulse width. A magnetic bearing gate drive circuit
123
is operative to control a magnetic bearing power amplifier
124
to drive electromagnet
21
.
Furthermore, a motor control circuit
131
outputs to a motor PWM circuit
132
a control signal based on a command input to sequence circuit
101
. Motor PWM circuit
132
outputs a PWMed control signal to a motor gate drive circuit
133
. Motor gate drive circuit
133
outputs a drive signal to motor power amplifier
104
. In response to the drive signal, motor power amplifier
104
drives motor stator
41
.
In the blood pump apparatus shown in
FIGS. 15 and 16
, magnetic bearing sensor
22
has characteristics slightly varying to reflect a difference of an individual blood pump from another individual one. As such, in sensor circuit
110
an adjustment needs to be made for each sensor. As such, controller
10
is not compatible with each blood pump, which is a bottleneck in mass production.
Furthermore, magnetic bearing power amplifier
124
, motor power amplifier
104
and the like generate significant heat attributed to switching-loss and controller
10
would also generate heat, which can have a negative effect on a human body when the apparatus is implanted therein.
SUMMARY OF THE INVENTION
Therefore a main object of the present invention is to provide a fluid pump apparatus reduced in size and weight and capable of efficiently release

Affiliated with

Also associated with

Rating

Fluid pump apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Fluid pump apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fluid pump apparatus will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3097824