JP7569770B2 - Syringe Pump - Google Patents

Description

The present invention relates to a syringe pump used to supply liquids such as liquid paint and hardeners for two-component paint to a coating machine.

Patent document 1 discloses an apparatus for supplying liquid paint and cleaning liquid in association with a painting robot equipped with a paint gun, the apparatus including a syringe pump. This type of syringe pump fills a filling chamber of a cylinder with liquid paint or the like, and then slides a piston to push the paint out of the filling chamber. The pushed-out paint is supplied to the paint gun.

The syringe pump disclosed in Patent Document 1 has a port on the peripheral wall of the end of the cylinder, through which not only paint but also cleaning liquid and cleaning air are supplied to the cylinder. The extrusion piston, which is slidably inserted into the cylinder, has a front seal ring, a rear seal ring, and gaps between the front and rear seal rings on its peripheral surface. The syringe pump is cleaned when the piston is in the extrusion position, that is, when the extrusion piston is located at the end of the cylinder and the port faces the gap between the front and rear rings.

Patent Document 2 proposes a syringe pump in which a piston seat that defines the stroke end of the extrusion piston is provided at the end of the cylinder, and cleaning liquid and cleaning air are supplied to the gap between the front and rear seal rings on the circumferential surface of the extrusion piston through a recess in this piston seat.

JP 2004-344788 A JP 2019-74000 A

Both Patent Documents 1 and 2 are based on the technical idea of performing a cleaning process for a syringe pump with the extrusion piston positioned at the stroke end, but this cleaning process has the problem that it is not possible to completely clean the piston, leaving behind residue. In order to improve this problem, Patent Document 2 proposes cleaning and drying the extrusion piston while it is positioned at the end of the cylinder, and once drying is complete, supplying sealing liquid to the gap through a port that opens into a recess in the piston seat, filling the gap with sealing liquid.

The object of the present invention is to provide a syringe pump that allows the cylinder to be cleaned without being restricted by the position of the extrusion piston.

The above technical problem is solved by the present invention.
A syringe pump in which a filling chamber in a cylinder is defined by a piston inserted into the cylinder, and the syringe pump supplies a liquid in the filling chamber in the cylinder to a coating machine,
a cleaning space defined by first and second seal rings disposed on a circumferential surface of the piston and spaced apart from each other in a moving direction of the piston and an inner wall of the cylinder;
a cleaning liquid supply port provided on a peripheral surface of the piston and opening at a position facing the cleaning space between the first and second seal rings;
a cleaning liquid discharge port provided on a circumferential surface of the piston and opening at a position facing the cleaning space;
a cleaning liquid supply passage provided in a piston rod connected to the piston and connected to the cleaning liquid supply port;
a cleaning liquid discharge passage provided in the piston rod and connected to the cleaning liquid discharge port;
a cleaning liquid supply control valve provided in the cleaning liquid supply passage;
a cleaning liquid discharge control valve provided in the cleaning liquid discharge passage,
By opening and closing the cleaning liquid supply control valve and the cleaning liquid discharge control valve, the cleaning liquid can be pressure-fed into the cleaning space and the cleaning liquid in the cleaning space can be discharged to the outside ,
a cleaning liquid supply port that opens toward the cleaning space is formed on a circumferential surface of the piston by bending an end of the cleaning liquid supply passage inside the piston;
This can be achieved by providing a syringe pump characterized in that a cleaning liquid discharge port that opens into the cleaning space is formed on the circumferential surface of the piston by bending the end of the cleaning liquid discharge passage inside the piston .

According to the present invention, the cylinder can be cleaned even when the piston is at the end of the cylinder or while the piston is moving. The detailed effects and other objects of the present invention will become apparent from the detailed description of the preferred embodiment of the present invention below.

1 is an overall system diagram of a paint supplying device including a syringe pump according to an embodiment of the present invention. FIG. 2 is an enlarged view of a main portion of FIG. 1, illustrating washing of the syringe pump. 11 is a cross-sectional view of the piston, illustrating the end portions of a cleaning liquid supply passage and a cleaning liquid discharge passage, and the arrangement of a cleaning liquid supply port and a cleaning liquid discharge port connected thereto. FIG. 4 is a cross-sectional view showing a modification of FIG. 3, illustrating a modification of the arrangement of the end portions of the cleaning liquid supply passage and the cleaning liquid discharge passage, and the cleaning liquid supply port and the cleaning liquid discharge port connected thereto. FIG. FIG. 5 is a cross-sectional view showing a modification of the example shown in FIG. 4 . 11 is a cross-sectional view showing an example in which a cleaning liquid supply port is configured with a plurality of nozzle holes. FIG. FIG. 7 is a longitudinal sectional view related to FIG. 6.

Below, a preferred embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an overall system diagram of a paint supplying device 2. To give an overview of the paint supplying device 2, the paint supplying device 2 includes a syringe pump 4, which supplies paint to a bell-type paint sprayer 6 mounted on, for example, a painting robot. Paint, more specifically, a hardener for a two-component paint, is supplied to the syringe pump 4 from a liquid paint source 8. The paint supplying device 2 has a cleaning system 10 for cleaning the syringe pump 4.

The syringe pump 4 has a cylinder 40 and a piston 42 inserted into the cylinder 40, and the piston 42 defines a filling chamber 44 inside the cylinder. At the end of the cylinder 40, a paint receiving passage 46 that leads to the liquid paint source 8 and a paint supply passage 48 that leads to the sprayer 6 are formed.

The piston 42 is provided continuously with one end of the piston rod 50, and the piston 42 is driven by the forward and backward movement of the piston rod 50. The movement of the piston 42 fills the cylinder filling chamber 44 with paint from the paint source 8, and the paint in the filling chamber 44 is pushed out of the cylinder 40 and supplied to the sprayer 6. These controls are controlled by a first opening and closing valve (a paint receiving control valve for the cylinder filling chamber) 52 of the paint receiving passage 46 and a second opening and closing valve (a paint filling control valve for the sprayer) 54 of the paint supply passage 48. That is, by opening the first opening and closing valve 52, the paint is filled from the paint source 8 into the cylinder filling chamber 44. By opening the second opening and closing valve 54, the paint in the cylinder filling chamber 44 can be supplied to the sprayer 6.

Figure 2 is an enlarged view of the main parts of the cleaning system 10. Referring to Figures 1 and 2, the cleaning of the syringe pump 4 will be described. The cleaning system 10 includes a cleaning liquid source 100. A cleaning liquid, typically an organic solvent, is stored in the cleaning liquid source 100. The cleaning liquid in the cleaning liquid source 100 is pumped by a cleaning liquid pump 120 that is constantly operating. The cleaning system 10 includes first and second passages 102, 104 formed inside the piston rod 50 and extending in the axial direction of the piston rod 50. The first passage 102 is connected to the cleaning liquid source 100.

The first and second passages 102, 104 have ends 102a, 104a that extend from the piston rod 50 to the piston 42, and the ends 102a, 104a of the first and second passages 102, 104 preferably bend 90 degrees to extend radially outward and open onto the circumferential surface of the piston 42. The open end of the first passage 102 is called the "cleaning liquid supply port" and is designated by the reference character Pt(su). The open end of the second passage 104 is called the "cleaning liquid discharge port" and is designated by the reference character Pt(ex).

The piston 42 has first and second seal rings 56, 58 on its circumferential surface, spaced apart in the direction of movement of the piston 42, and a gap, i.e., a cleaning space S, is formed between the first and second seal rings 56, 58. The above-mentioned cleaning liquid supply port Pt(su) and cleaning liquid discharge port Pt(ex) are arranged facing the cleaning space S.

The first passage 102 and its end 102a, which communicates with the cleaning liquid source 100, constitute a "cleaning liquid supply passage" that supplies cleaning liquid to the cleaning space S, and a first opening/closing valve 110 (Fig. 1) is interposed in this first passage 102. The first opening/closing valve 110 is a "cleaning liquid supply control valve" that controls the supply of cleaning liquid to the cleaning space S. By opening the first opening/closing valve 110, the cleaning liquid from the cleaning liquid source 100 passes under pressure through the first passage (cleaning liquid supply passage) 102 and is discharged into the cleaning space S through the cleaning liquid supply port Pt(su).

On the other hand, the second passage 104 and its end 104a form a "cleaning liquid discharge passage" that discharges the cleaning liquid from the cleaning space S to the outside, and a second opening/closing valve 112 (Figure 1) is interposed in this second passage 104. The second opening/closing valve 112 is a "cleaning liquid discharge control valve" that controls the discharge of the cleaning liquid in the cleaning space S, and by opening the second opening/closing valve 112, the cleaning liquid in the cleaning space S is discharged to the outside through the cleaning liquid discharge port Pt(ex) and the second passage (cleaning liquid discharge passage) 104. The cleaning liquid discharged to the outside may be filtered and reused.

The control of the first opening/closing valve (cleaning liquid supply control valve) 110 and the second opening/closing valve (cleaning liquid discharge control valve) 112 has the following three modes.

Normal control mode (sealed mode) :
Under the normal control mode, a series of operations for supplying paint from the syringe pump 4 to the bell-type sprayer 6 is executed. In the normal control mode, the first opening/closing valve (cleaning liquid supply control valve) 110 is opened. Meanwhile, the second opening/closing valve (cleaning liquid discharge control valve) 112 is closed. By maintaining the first opening/closing valve 110 open while maintaining the second opening/closing valve 112 closed, the state in which the pump pressure acts on the cleaning liquid in the cleaning space S can be continued. By continuing to pressurize the cleaning liquid in the cleaning space S, back pressure can be continued to be applied to the first and second seal rings 56 and 58, and the paint can be prevented from entering the cleaning space S. That is, by executing the normal control mode (sealing mode), the pressure state of the cleaning space S can be controlled by utilizing the pressure of the cleaning liquid supplied to the cleaning space S, and the paint can be prevented from entering the cleaning space S.

Second control mode (circulation mode) :
Both the first opening/closing valve (cleaning liquid supply control valve) 110 and the second opening/closing valve (cleaning liquid discharge control valve) 112 are opened. As a result, the cleaning liquid pumped from the cleaning liquid source 100 via the cleaning liquid pump 120 is supplied to the cleaning space S, and the cleaning liquid in the cleaning space S is discharged. The discharged cleaning liquid is filtered and reused. As a result, the cleaning liquid can be supplied to the cleaning space S and discharged, and the discharged cleaning liquid can be supplied to the cleaning space S again. By operating the piston 42 under this circulation of the cleaning liquid, dirt on the inner wall surface of the cylinder 40 can be removed while the piston 42 is moving and when it is located at the cylinder end.

Third control mode (cleaning solution replacement mode) :
The cleaning liquid filled in the cleaning space S can be replaced, for example, periodically, by opening both the first opening/closing valve (cleaning liquid supply control valve) 110 and the second opening/closing valve (cleaning liquid discharge control valve) 112 to replace the cleaning liquid in the cleaning space S and then closing the first and second opening/closing valves 110, 112.

Air removal process :
As a preparation step before the normal control mode is executed, air is removed from the cleaning space S. The air is removed in the following procedure.
(1) The first opening/closing valve (cleaning liquid supply control valve) 110 and the second opening/closing valve (cleaning liquid discharge control valve) 112 are both opened.
(2) Next, the second opening/closing valve (cleaning liquid discharge control valve) 112 is repeatedly opened and closed to thoroughly remove air from within the cleaning space S.
(3) After the air in the cleaning space S has been removed, the second opening/closing valve (cleaning liquid discharge control valve) 112 is closed.
By carrying out the above steps (1) to (3), it is possible to remove air from within the cleaning space S. Incidentally, if air is present in the cleaning space S, there is a risk that the thin film of paint formed on the inner wall of the cylinder 40 will harden due to this air.

The normal control mode, the second control mode, and the third control mode are controlled by the controller CU. That is, the first opening/closing valve (cleaning liquid supply control valve) 110 and the second opening/closing valve (cleaning liquid discharge control valve) 112 are controlled to open and close by the controller CU. The normal control mode, the second control mode, and the third control mode are stored in the memory 150 associated with the controller CU, and the controller CU selects one of the normal control mode, the second control mode, and the third control mode under preset conditions, and executes the selected control mode.

According to the cleaning system 10 included in the embodiment, a cleaning liquid supply port Pt(su) and a cleaning liquid discharge port Pt(ex) facing the cleaning space S surrounded by the first and second seal rings 56 and 58 of the piston 42 are formed on the circumferential surface of the piston 42. A first passage (cleaning liquid supply passage) 102 and a second passage (cleaning liquid discharge passage) 104 leading to the cleaning liquid supply port Pt(su) and the cleaning liquid discharge port Pt(ex) are formed inside the piston rod 50. As a result, the cleaning system 10 included in the embodiment can be operated in any of the normal control mode, the second control mode, and the third control mode even when the piston 42 is located at the cylinder end or when the piston 42 is moving. That is, the cleaning system 10 included in the embodiment can pressure-feed the cleaning liquid to the cleaning space S at any time. Therefore, it is not necessary for the piston to be located at the cylinder end during cleaning as in the conventional case, and therefore the problem that cleaning must be interrupted until the piston reaches the cylinder end can be solved.

FIG. 3 is a horizontal cross-sectional view of the piston 42. As shown in FIG. 3, the end 102a of the first passage (cleaning liquid supply passage) 102 can be bent, for example, 90 degrees and extended radially outward, to open the cleaning liquid supply port Pt(su) facing the cleaning space S. Similarly, the end 104a of the second passage (cleaning liquid discharge passage) 104 can be bent 90 degrees and extended radially outward, to open the cleaning liquid discharge port Pt(ex) facing the cleaning space S. Preferably, the cleaning liquid supply port Pt(su) and the cleaning liquid discharge port Pt(ex) are disposed radially opposite each other when viewed in a plane. As a result, the cleaning liquid discharged under pressure from the cleaning liquid supply port Pt(su) flows in both clockwise and counterclockwise directions in the cleaning space S having a circular cross section in FIG. 3, reaches the cleaning liquid discharge port Pt(ex), and is discharged through the cleaning liquid discharge port Pt(ex). As a result, the inner wall surface of the cylinder 40 can be cleaned by the cleaning liquid.

Figure 4 shows modified examples of the arrangement of the cleaning liquid supply port Pt(su) and the end 102a of the first passage (cleaning liquid supply passage) 102, and the arrangement of the cleaning liquid discharge port Pt(ex) and the end 104a of the second passage (cleaning liquid discharge passage) 104. In Figure 4, Cl indicates the passage axis of the end 102a of the first passage (cleaning liquid supply passage) 102. Tl indicates the tangent of the peripheral surface of the piston 42 that contacts the opening of the end 102a of the first passage (cleaning liquid supply passage) 102, i.e., the cleaning liquid supply port Pt(su).

The passage axis Cl of the end 102a of the first passage (cleaning liquid supply passage) 102 is not perpendicular to the tangent line Tl, and the intersection angle θ1 between the passage axis Cl of the end 102a and the tangent line Tl is smaller than 90 degrees. In other words, the end 102a of the first passage (cleaning liquid supply passage) 102 extends obliquely with respect to the circumferential surface of the piston 42 and opens into the cleaning space S through the cleaning liquid supply port Pt(su). By inclining the extension direction of the end 102a of the first passage (cleaning liquid supply passage) 102 in this way, as shown by the arrow in FIG. 4, the cleaning liquid discharged from the single cleaning liquid supply port Pt(su) creates a flow oriented in one direction, that is, counterclockwise. This flow of cleaning liquid rotates counterclockwise in the cleaning space S, which has a circular cross section, and reaches the single cleaning liquid discharge port Pt(ex). That is, by inclining the end 102a of the first passage (cleaning liquid supply passage) 102, a flow of cleaning liquid discharged from the cleaning liquid supply port Pt(su) into the cleaning space S can be created that swirls in one direction, and the inner wall surface of the cylinder 40 can be cleaned by the swirling flow generated in the cleaning space S.

Regarding the swirling flow of the cleaning liquid in the cleaning space S, it is better for the intersection angle θ1 to be small. Figure 5 shows a modified example of Figure 4. In Figure 4, the end 102a of the first passage (cleaning liquid supply passage) 102 is configured as a straight hole, but instead, by configuring the end 102a as a curved hole, the intersection angle θ2 between the passage axis Cl and the tangent line Tl of the end 102a can be made smaller than the intersection angle θ1 in Figure 4.

Referring to Figures 4 and 5, the cleaning liquid discharge port Pt(ex) is preferably located on the same side of the circumferential surface of the piston 42 as the cleaning liquid supply port Pt(su). In addition, the cleaning liquid discharge port Pt(ex) is preferably located at a position overlapping the cleaning liquid supply port Pt(su) when the piston 42 is viewed in a plan view. This allows the inner wall surface of the cylinder 40 to be thoroughly cleaned by the swirling flow generated in the cleaning space S. In addition, all of the cleaning liquid filling the cleaning space S can be discharged through the cleaning liquid discharge port Pt(ex) and the second passage (cleaning liquid discharge passage) 104 without remaining in the cleaning space S.

Furthermore, as shown in Figures 4 and 5, it is preferable to arrange the end 104a of the second passage (cleaning liquid discharge passage) 104 at an incline in the opposite direction to the end 102a of the first passage (cleaning liquid supply passage) 102. This allows the cleaning liquid to be smoothly received by the cleaning liquid discharge port Pt(ex) that opens toward the cleaning liquid swirling in the cleaning space S.

In the above-described embodiment, a configuration is adopted in which one cleaning liquid supply port Pt(su) is opened to the cleaning space S. As a modified example, the cleaning liquid may be discharged under pressure through multiple holes (these holes are called "nozzle holes") into the cleaning space S to assist the swirling flow of the cleaning liquid in the cleaning space S.

A specific example of supplying the cleaning liquid under pressure to the cleaning space S through multiple nozzle holes will be described with reference to Figures 6 and 7. The piston 42 is provided with a circumferential ring 200 at a position corresponding to the cleaning liquid supply port Pt(su). The circumferential ring 200 is coaxial with the piston 42. The circumferential ring 200 has a recess 200a that cooperates with the peripheral surface of the piston 42 to form an intermediate groove 202. The intermediate groove 202 is continuous in the circumferential direction. The circumferential ring 200 has the groove 202 that both extend continuously in the circumferential direction and multiple nozzle holes 204 that communicate with the cleaning space S, and the nozzle holes 204 are preferably arranged at equal intervals in the circumferential direction of the circumferential ring 200.

In FIG. 6, reference symbol O indicates the center of the circumferential ring 200. The center line L2 of each nozzle hole 204 is inclined with respect to the imaginary line L1 connecting the center O and each nozzle hole 204. In the example shown in FIG. 6, the nozzle holes 204 are inclined at an angle α in the counterclockwise direction. As a result, in the cleaning space S, the cleaning liquid ejected under pressure from each nozzle hole 204 swirls in the counterclockwise direction.

If the circumferential ring 200 having a plurality of nozzle holes 204 arranged at equal intervals in the circumferential direction is regarded as one component constituting the piston 42, the piston 42 shown in Figures 6 and 7 can be understood as having a plurality of nozzle holes 204 arranged at intervals in the circumferential direction facing the cleaning space S. In other words, the example shown in Figures 6 and 7 shows a cleaning liquid supply port Pt(su) composed of a plurality of nozzle holes 204.

The multiple nozzle holes 204 that actually constitute the cleaning liquid supply port Pt(su) are inclined in one direction, and the cleaning liquid is ejected under pressure from these inclined multiple nozzle holes 204 toward the cleaning space S, thereby assisting the swirling flow in the cleaning space S by the multiple nozzle holes 204.

Referring to FIG. 1, the cleaning liquid pump 120 is preferably controlled by a controller CU. It is preferable to variably control the flow rate of the cleaning liquid pump 120 by presetting desired flow rates of the cleaning liquid pump 120 corresponding to the normal control mode, the second control mode, and the third control mode.

4 Syringe pump 40 Cylinder 42 Piston 44 Paint filling chamber in cylinder 46 Paint receiving passage 48 Paint supply passage 50 Piston rod 52 First opening and closing valve (paint receiving control valve for the filling chamber in the cylinder)
54 Second opening and closing valve (paint filling control valve for the sprayer)
56 First seal ring 58 Second seal ring S Cleaning space 6 Coating machine 8 Liquid paint source 10 Cleaning system 100 Cleaning liquid source 102 First passage (cleaning liquid supply passage)
102a End of cleaning liquid supply passage 104 Second passage (cleaning liquid discharge passage)
104a End of cleaning liquid discharge passage 110 Cleaning liquid supply control valve 112 Cleaning liquid discharge control valve 120 Cleaning liquid pump 150 Memory 204 Nozzle hole
Pt(su) cleaning solution supply port
Pt(ex) Cleaning solution discharge port CU Controller

Claims (10)

A syringe pump in which a filling chamber in a cylinder is defined by a piston inserted into the cylinder, and the syringe pump supplies a liquid in the filling chamber in the cylinder to a coating machine,
a cleaning space defined by first and second seal rings disposed on a circumferential surface of the piston and spaced apart from each other in a moving direction of the piston and an inner wall of the cylinder;
a cleaning liquid supply port provided on a peripheral surface of the piston and opening at a position facing the cleaning space between the first and second seal rings;
a cleaning liquid discharge port provided on a circumferential surface of the piston and opening at a position facing the cleaning space;
a cleaning liquid supply passage provided in a piston rod connected to the piston and connected to the cleaning liquid supply port;
a cleaning liquid discharge passage provided in the piston rod and connected to the cleaning liquid discharge port;
a cleaning liquid supply control valve provided in the cleaning liquid supply passage;
a cleaning liquid discharge control valve provided in the cleaning liquid discharge passage,
By opening and closing the cleaning liquid supply control valve and the cleaning liquid discharge control valve, the cleaning liquid can be pressure-fed into the cleaning space and the cleaning liquid in the cleaning space can be discharged to the outside ,
a cleaning liquid supply port that opens toward the cleaning space is formed on a circumferential surface of the piston by bending an end of the cleaning liquid supply passage inside the piston;
a cleaning liquid discharge port that opens into the cleaning space on a circumferential surface of the piston by bending an end of the cleaning liquid discharge passage inside the piston . 2. The syringe pump according to claim 1 ,
a syringe pump , wherein the cleaning liquid supply port and the cleaning liquid discharge port are disposed opposite to each other in a radial direction when the piston is viewed in a plan view. 2. The syringe pump according to claim 1 ,
The syringe pump, wherein the cleaning liquid discharge port is disposed at a position overlapping with the cleaning liquid supply port when the piston is viewed in a plan view. 4. The syringe pump according to claim 3 ,
A syringe pump, wherein a center line of the end of the cleaning liquid supply passage is inclined with respect to a tangent line of the piston where the end of the cleaning liquid supply passage intersects, thereby forming a swirling flow of the cleaning liquid discharged from the cleaning liquid supply port. 2. The syringe pump according to claim 1,
The cleaning liquid supply port is composed of a plurality of nozzle holes,
The plurality of nozzle holes are circumferentially spaced apart and inclined in one direction. 6. The syringe pump according to claim 1,
a paint receiving passageway opening at an end of said cylinder and communicating with a source of liquid paint;
a paint receiving control valve disposed in the paint receiving passage and controlling the receiving of paint into the cylinder filling chamber;
a paint supply passage opening at an end of the cylinder and communicating with the coating machine;
The syringe pump further comprises a coating machine filling control valve disposed in the paint supply passage for controlling filling of paint into the coating machine. 7. The syringe pump according to claim 6 ,
A syringe pump supplies a cleaning liquid under pressure to the cleaning space through the cleaning liquid supply passage. 8. The syringe pump according to claim 6 ,
a controller for controlling the cleaning liquid supply control valve and the cleaning liquid discharge control valve;
The controller executes a normal control mode;
In the normal control mode, the cleaning fluid supply control valve is opened while the cleaning fluid discharge control valve is closed. 9. The syringe pump according to claim 8 ,
The controller is operable in a second control mode;
In the second control mode, the cleaning liquid supply control valve and the cleaning liquid discharge control valve are both opened. 10. The syringe pump according to claim 8 ,
The controller is operable to implement a third control mode;
In the third control mode, the cleaning liquid supply control valve and the cleaning liquid discharge control valve are both opened to replace the cleaning liquid in the cleaning space, and then the cleaning liquid supply control valve and the cleaning liquid discharge control valve are closed .

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