JPH0541269Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a piston pump used as a pump for a dialysis machine, etc.

(Prior Art) As a pump for a dialysis apparatus, for example, a piston pump as shown in FIG. 2 is used.

In this pump, a piston 5 is installed inside the cylinder 50.
A seal 52 is interposed between the cylinder 50 and the piston 51, and the piston 51 is connected to the drive shaft 5.
3 is screwed into the cylinder 5, and the drive shaft 53 is inserted into the cylinder 5.
An output shaft 55 of an electric motor 54, which is capable of forward and reverse rotation, is connected to one end of a drive shaft 53 via a coupling ring 56. .

By the way, in the above conventional example, the drive shaft 53
was supported by a bearing 57 only at one location between the piston 51 and the electric motor 54.

(Problem to be solved by the invention) For this reason, in the above conventional example, when the pump is driven, the drive shaft 53 and the piston 51 tend to move, the accuracy of the discharge amount is poor, and the dialysate flows out from between the cylinder 50 and the piston 51. There was a problem that it was easy to leak.

Further, due to the vibration of the piston 51, the seal 52 and the cylinder 50 are worn out and damaged at an early stage, resulting in a short service life.

An object of the present invention is to provide a piston pump that can solve the above problems.

(Means for Solving the Problems) In order to solve the above problems, the means adopted by the present invention is such that a piston is provided in a cylinder so as to be movable in the axial direction and unrotatable around the axis. In a piston pump in which a seal is interposed between the piston and the piston, a drive shaft is screwed into the piston, and the drive shaft is supported by a fixed member so as to be immovable in the axial direction but rotatable around the axis. , at a point where the drive shaft is supported on both sides of the piston's travel range.

An output shaft of a reversible motor may be connected to one end of the drive shaft via a coupling.

It may also include a detection means for detecting that the piston is at each outermost position of the movement range and rotating the motor in reverse.

(Function) When a piston pump is driven, the drive shaft is driven forward and backward, causing the piston to reciprocate in the axial direction, sucking liquid into the cylinder, and discharging the sucked liquid. .

(Example) Hereinafter, an example in which the present invention is applied to a piston pump of a dialysis machine will be explained based on the drawing of Fig. 1. Fig. 1 shows a piston pump of a dialysis machine,
A piston pump has a cylinder 1 and a piston 2.
, a drive shaft 3, an electric motor 4, a piston detection means 5, an encoder 6 for measuring a discharge amount, and the like.

The cylinder 1 consists of a cylindrical body 8 and a pair of lids 9 and 10 that are detachably attached to both ends of the cylindrical body 8 and close the openings at both ends.
A connection hole 13 for connecting a tube 12 to a liquid chamber 11 in the cylinder 1 is formed.

The piston 2 is provided in the cylinder 1 so as to be movable in the axial direction, and a guide shaft 14 fixed to the right side cover 10 of the cylinder 1 is inserted into the piston 2 parallel to the axial center. 2
is not rotatable about the axis relative to the cylinder 1.

A through hole 17 is formed in the axial center of the piston 2, and a female screw portion 18 is formed in the inner peripheral surface of the through hole 17 except for the left end. Further, a circumferential groove 19 is formed at the left end of the outer circumferential surface of the piston 2, and a seal 20 that slidably abuts on the inner circumferential surface of the cylindrical body 8 of the cylinder 1 is provided in the circumferential groove 19. .
For example, an O-ring is used as the seal 20.

The drive shaft 3 is supported on both sides of the movement range of the piston 2 so as to be immovable in the axial direction and rotatable around the axis. It is supported as described above via 21 and 22.

The left end of the drive shaft 3 is connected to the left side cover 9 of the cylinder 1.
The bearing holder 24 is covered by a bearing holder 24 which is detachably fixed to the cylinder 1, and its right end protrudes rightward through the right side cover 10 of the cylinder 1.

Further, the drive shaft 3 is inserted into the through hole 17 of the piston 2, and a male screw portion 26 formed in the middle thereof is
It is screwed into the female screw portion 18 of the through hole 17 .

The electric motor 4 is capable of forward and reverse rotation, is arranged on the right side of the cylinder 1, and is mounted on the motor base 2.
8. Mounting bolt 29, right side cover 10 of cylinder 1
It is removably fixed to the cylindrical body 8 of the cylinder 1 via.

The output shaft 31 of the electric motor 4 faces the right end portion of the drive shaft 3 in the axial direction, and both shafts 31 and 3 are connected via a coupling ring 32.

The piston detection means 5 detects that the piston 2 is at each outermost position of the movement range and reverses the electric motor 4, and in the embodiment, the detection shaft 34
and a pair of photo sensors 35 and 36.

The detection shaft 34 is removably screwed into the right end of the piston 2, and extends to the right through a hole 38 in the right cover 10 of the cylinder 1.

The photo sensors 35 and 36 are arranged side by side in the left-right direction between the right side cover 10 of the cylinder 1 and the motor base 28, and are detachably attached thereto to detect the right end of the detection shaft 34.

The discharge amount measurement encoder 6 measures the discharge amount of the pump by detecting the rotational speed of the drive shaft 3 and the output shaft 31, and includes a detection disk 40 fixed to the coupling 32 and having a slit, The photo sensor 42 is attached to the right side lid body 10 of the disk via a mounting shaft 41 and detects the slit in the disk.

Additionally, 44 is a seal.

According to the embodiment configured as described above, when driving the piston pump of the dialysis machine, the electric motor 4
The output shaft 31 of the output shaft 31 is rotationally driven, and thereby the drive shaft 3 is rotationally driven via the coupling 32.

In this case, the piston 2 is provided in the cylinder 1 so as to be movable in the axial direction and unrotatable around the axis, and the female threaded portion 18 of the piston 2 is provided.
Since the male screw portion 26 of the drive shaft 3 is screwed into the piston 2, the piston 2 moves in the axial direction.

Then, when the piston 2 reaches the outermost position of the movement range, one of the photo sensors 35 and 36 detects the right end of the detection shaft 34 of the piston detection means 5, and the electric motor 4 is reversely rotated. 2 moves in the opposite direction to the above.

In this way, the piston 2 reciprocates in the axial direction, thereby sucking dialysate into the liquid chamber 11 of the cylinder 1, and discharging the sucked dialysate.

At this time, since the drive shaft 3 is supported by bearings 21 and 22 on both sides of the movement range of the piston 2, the drive shaft 3 and the piston 2 do not move, and therefore,
The accuracy of the discharge amount of the pump can be improved, and there is no fear that the dialysate will leak from between the cylinder 1 and the piston 2.

Furthermore, as described above, since the piston 2 does not wobble, the seal 20 and the cylindrical body 8 of the cylinder 1 are not worn out or damaged early, and can have a long life.

In the example, a photo sensor, which is a non-contact type sensor, was used as the piston detection means.
A contact type sensor may also be used.

Further, in the embodiment, the piston and the output shaft are connected by a screw, but the concept of a screw also includes a helical spline.

Furthermore, although the present invention is applied to a piston pump for a dialysis machine in the embodiment, the present invention can also be applied to other piston pumps.

(Effects of the invention) As detailed above, according to the invention, the drive shaft is supported on both sides of the movement range of the piston, so the drive shaft and piston do not move, and therefore the pump discharge amount is reduced. In addition to improving the accuracy of the process, there is no risk of liquid leaking between the cylinder and piston.
Furthermore, as mentioned above, since the piston does not wobble, the seals and cylinders do not wear out or get damaged early, allowing them to have a long life.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing one embodiment of the present invention;
The figure is a sectional view showing a conventional example. DESCRIPTION OF SYMBOLS 1... Cylinder, 2... Piston, 3... Drive shaft, 4... Electric motor, 5... Piston detection means, 18... Female screw portion, 20... Seal, 21,
22...Bearing, 26...Male screw portion, 31...Output shaft, 32...Coupling.

Claims (1)

[Claims for Utility Model Registration] (1) A piston is provided in the cylinder so that it can move freely in the axial direction and cannot rotate around the axis, a seal is interposed between the cylinder and the piston, and the piston has a drive shaft. In a piston pump, in which the drive shaft is supported by a fixed member so as to be immovable in the axial direction but rotatable around the axis, the drive shaft is supported on both sides across the movement range of the piston. A piston pump characterized by: (2) The piston pump according to claim 1, wherein an output shaft of a motor capable of forward and reverse rotation is connected to one end of the drive shaft via a coupling. (3) The piston pump according to claim 2, further comprising detection means for detecting that the piston is at each outermost position of the movement range and rotating the motor in reverse.