JPH04303188A - Diaphragm pump device - Google Patents

Abstract

PURPOSE:To mix two liquids to be mixed at a high ratio with high accuracy by providing the second pump unit in which the diameter of a piston is made smaller than the diameter of a diaphragm, and connecting the respective rod ends of pistons to each one end of connecting means, the other ends of which are oscillated centering round a supporting point with the reciprocating movement of a pump shaft. CONSTITUTION:A diaphragm pump device in the title comprises the first pump unit 2 having a pair of case bodies 5a, 6a with a diaphragm 6 in the interior thereof and the second pump unit 3 having a pair of case bodies 12a, 12b with a diaphragm 13 and a piston 14 for operating the diaphragm through the pressure of a liquid in the interior thereof. Rods 14a,14b of pistons 14 are connected to the other ends of connecting means 19 for transmitting the movement of a pump shaft 7 for connecting two diaphragms 6,6 of the first pump unit 2, and the outside diameter of the piston 14 is made smaller than the diameter of the diaphragm 13, so that the reciprocating motion of the piston 14 is reduced and transmitted to the diaphragm 13 through a fluid.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention enables two pump bodies using diaphragms to operate smoothly at an accurate stroke ratio, thereby dispensing two paint materials at an appropriate ratio and even at a high ratio. The present invention relates to a diaphragm pump device that can be extracted with high accuracy even when the pump is in use.

0002

[Prior Art] For example, when using a two-component mixed type coating agent that is cured by mixing a main agent and an auxiliary agent, the two coating agents must be mixed in a stable and accurate ratio due to constraints such as curing time. Moreover, it is required to mix quickly depending on the amount used.

[0003] Therefore, the applicant of the present invention
In Publication No. 468, as shown in FIG. 12, the pump shafts a of two diaphragm pumps whose pump shafts a are parallel to each other are connected by a connecting means b, and the pump shafts a are interlocked to move back and forth. proposed to devise a diaphragm pump device that could be used to generate a diaphragm pump, and to connect the device to a stirrer.

[0004] Also, the present applicant has partially disclosed a lever-shaped member that swings about a fulcrum K as the connecting means b, and the fulcrum K is configured so that its position can be changed in the longitudinal direction. are doing. As a result, each of the pump shafts a, a can freely change its movement stroke ratio according to the fulcrum position, and the paint can be continuously supplied from each pump body at an appropriate ratio.

[0005]

[Problem to be Solved by the Invention] However, although it is possible to change the stroke ratio by moving the position of the fulcrum k, if the two liquids are mixed at a high mixing ratio exceeding 5:1, the mixing ratio It was found that the accuracy decreased significantly. This is due to the fact that the position of the fulcrum part k is biased toward one of the pump bodies, and the smoothness of operation is reduced due to play in the joint part between each pump shaft a, a and the connecting means b, and in the fulcrum part k of the connecting means b. By lowering the. Therefore, it has been found that when mixing two liquids at a high ratio, the problem cannot be solved simply by moving the position of the fulcrum k.

[0006] As a result of intensive research in order to solve the above-mentioned problem, the inventor provided the pump shaft of one pump body with a piston having a diameter smaller than the diameter of the diaphragm, thereby allowing the pump shaft of the pump body to move through the liquid. They focused on the fact that the diaphragm can be operated by further decelerating the engine speed, and completed the present invention.

The object of the present invention is to provide a diaphragm device that can mix two liquids at a high ratio with high precision by operating two pump bodies using diaphragms at a high ratio and with high precision. There is.

[0008]

[Means for Solving the Problems] The present invention provides a pair of case bodies each having a cavity inside and a hole communicating with the cavity, which are spaced apart from each other and arranged with the holes facing inward from each other. a case, a diaphragm that divides each of the cavities into an inner working chamber and an outer pump chamber; a pump shaft that fixes the diaphragm at both ends and that is sealed and inserted through the hole; and a pump shaft that is electrically connected to the pump chamber and inserted through the hole; A valve body comprising a check valve that allows fluid to freely flow into the pump chamber and a check valve that allows fluid to freely flow out from the pump chamber, and which is capable of supplying and discharging working fluid to and from each of the working chambers. A first pump body provided with a working hole for reciprocating the pump shaft by alternately supplying and discharging the working fluid, and a pair of case bodies each having a cavity therein and a hole communicating with the cavity are spaced apart from each other. a diaphragm that divides each of the cavities into an inner fluid chamber and an outer pump chamber; A valve consisting of a piston that applies pressure to the diaphragm, a check valve that communicates with the pump chamber and allows fluid to flow into the pump chamber, and a check valve that allows fluid to flow freely from the pump chamber. The second pump body has a second pump body having a piston having an outer diameter smaller than the diameter of the diaphragm, and one end of the second pump body engages with the pump shaft to move the pump shaft back and forth about the fulcrum. This is a diaphragm pump device in which each rod end of the piston is connected to the other end of a swinging lever-like connecting means.

[0009] The fulcrum of the connecting means may be provided on a movable fitting whose position is changed in the length direction of the connecting means.

[0010] Also, the diaphragm of the second pump body is
Preferably, biasing means are provided for biasing the diaphragm pump toward the liquid chamber.

The fluid may be a liquid such as oil or water, or a gas such as compressed air, but is preferably a liquid in order to ensure reliable operation of the diaphragm.

0012

[Operation] The second pump body includes a piston that slides through its hole and causes the fluid pressure in the fluid chamber to act on the diaphragm by advancing, and the outer diameter of the piston is smaller than the diameter of the diaphragm. Therefore, the moving speed of the piston is reduced through the fluid to operate the diaphragm, and the amount of movement of the diaphragm becomes smaller than the stroke of the piston, making it possible to move the diaphragm minutely and adjusting the mixing ratio of the two liquids. It can be blended in a high ratio.

Furthermore, since the piston of the second pump body absorbs play between the piston and the connecting means by the fluid pressure in the fluid chamber, the stroke ratio between the first and second pumps can be maintained accurately and constant. This makes it possible to stabilize the supply ratio between each pump body.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the figure, a diaphragm pump device 1 includes a first pump body 2 with diaphragms 6 attached to both ends of a pump shaft 7.
, a second pump body 3 comprising a piston 14 that acts on the diaphragm 13 through fluid pressure, the pump shaft 7 and each rod 14a, 14b of the pistons 14, 14.
and connecting means 19 for connecting the two.

In this example, the first pump body 2 includes a case 5 consisting of a pair of case bodies 5a and 5b, a diaphragm 6, a pump shaft 7, and a valve body 8, as shown in FIG. The pump shaft 7 is disposed between the upper and lower frame plates 20 and 21 with the pump shaft 7 facing horizontally.

The case 5 consists of a pair of case bodies 5 consisting of an outer case piece 22 and an inner case piece 23 attached inside the outer case piece 22.
a, 5b, and the case 5 is formed by the case body 5a, 5b.
The inner case pieces 23, 23 are arranged inwardly and spaced apart from each other.

The outer case piece 22 has a recess 25 on its inner surface.
and a flange portion 26 around the recess 25, and the upper and lower ends of the flange portion 26 are connected to the upper frame plate 20 and the lower frame plate 21.
bolted to.

The inner case piece 23 has a surrounding flange portion 2.
7 to the outer case piece 22, and by providing a recess 28 on its outer surface, that is, the surface facing the outer case piece 22, each case body 5a, 5b has a recess 2 inside.
5 and 28 dense spaces H1 and H1 are formed, respectively. In addition, the inner case piece 23 has a hole 9 at its center that passes through the recess 28, and the case bodies 5a and 5b have the hole 9, which passes through the recess 28.
9 are arranged concentrically and facing each other.

Furthermore, the case bodies 5a and 5b are mounted with a diaphragm 6 sandwiched between the outer case piece 22 and the inner case piece 23, respectively, so that the diaphragm 6 closes the space H.
1 into an inner working chamber 10 and an outer pump chamber 11, and each diaphragm 6 is connected to an end of a pump shaft 7.

The pump shaft 7 is a long shaft that passes through the two holes 9, 9, and the diaphragm 6 is fixed between the collar plates 30, 31 which are tightened using nuts screwed into both ends of the shaft. . Further, the pump shaft 7 is slidably held by being inserted into the hole 9, and is sealed by a sealing material provided around the hole 9.

[0021] The outer case piece 22 has backstops attached to the lower vertical hole 32 and upper vertical hole 33 communicating with the pump chamber 11, respectively, to allow the paint to freely flow into the pump chamber 11. A valve body 8 consisting of a valve 8A and a check valve 8B that allows the paint to freely flow out from inside the pump chamber 11 is arranged. Further, the outer ends of the upper vertical hole 33 and the lower vertical hole 32 are communicated with through holes 35 and 36 provided in the upper frame plate 20 and the lower frame plate 21, respectively. The paint to be applied is the bottom vertical hole 32.
, 32 and flow into the pump chambers 11, 11 provided in the case bodies 5a, 5b, respectively, and pass through the upper vertical holes 33, 33 to join at the through hole 35.

[0022] The case 5 also includes an inner case piece 23.
, 23 have small diameter working holes 37a, 3 communicating with each working chamber 10.
7b is provided, and one end of the operating holes 37a, 37b communicates with, for example, a switching valve V attached to the upper frame plate 20.

As shown in FIG. 11, the switching valve V has a port I that communicates with a high-pressure air source X that pumps a working fluid such as high-pressure air into which the working fluid flows in, and a port O1 that discharges the working fluid.
, O2, ports R1 and R2 for exhaust, a port Q for pilot air outflow, and ports P1 and P2 for pilot air inflow, and the ports O1 and O2 are connected to the operating hole 3.
7a and 37b. Ports R1 and R2 are also connected to a silencer 38. In addition, the switching valve V slides the spool valve in one direction when high-pressure pilot air that is constantly applied from port Q flows into port P1 and returns, thereby switching ports I and O1, and ports O2 and R2. conducts inside it.

[0024] Also, due to the inflow of pilot air into port P2, the spool valve slides to the other side, so that port I and port O2
Also, the port O1 and the port R1 are electrically connected therein. Therefore, the first pump body 2 has a working chamber 10 provided in the case body 5a through which working fluid is supplied to the case body 5a through the port I, the port O1, and the working hole 37a by the inflow of pilot air into the port P1.
The pump shaft 7 can be moved toward the case body 5a by pushing the diaphragm 6 by the supplied working fluid. In such a case, the working chamber 1 provided in the case body 5b
The air inside 0 flows through the operating hole 37b, port O2, and port R2.
and is discharged to the outside air via a muffler 38. Furthermore, the pump shaft 7 can be moved toward the case body 5b by the pilot air flowing into the port P2. Therefore, the working holes 37a, 37b can reciprocate the pump shaft 7 by supplying and discharging the working fluid, and due to the alternating volume change of each pump chamber 11, 11 due to the reciprocating movement, one of the first pump bodies 2 is moved through the through hole. The fluid flowing in from 36 can be continuously discharged from through hole 35 .

[0025] The first pump body 2 has a pump shaft 7.
a controller 39 that detects the end position of the reciprocating movement of the pilot air and alternately switches the pilot air into and out of the ports P1 and P2;
is attached.

As shown in FIG. 3, the controller 39 includes a pair of contact plates 41 attached to the pump shaft 7 via, for example, an H-shaped fitting 40, and a pair of contact plates 41 attached to the upper frame plate 20, for example. A pair of switch valves S1 and S2 are mounted via a holding base 42 parallel to the pump shaft 7, and detect the end position by coming into contact with the abutment plate 41, and also turn on and off the pilot air flow path. I can do it.

The second pump body 3 includes a case 12 with holes 16 facing inward, a diaphragm 13, a piston 14, and a valve body 15.

As shown in FIG. 4, the case 12 is formed from a pair of hollow case bodies 12a and 12b formed by joining inner and outer case pieces 43 and 44, and each case body 12a
, 12b is fitted with a diaphragm 13 that divides the space H2 into an inner fluid chamber 17 and an outer pump chamber 18.

In this embodiment, the cavity H2 of the second pump body 3 is formed to have a smaller diameter and volume than the cavity H1 of the first pump body 2, and the hole 16 is formed in the inner case piece. It is formed to have a length of 43 mm.

The piston 14 has a rod 14a attached to a cylindrical piston ring 14A having a blind hole in the center facing the cavity H1.
(14b), and is airtightly inserted into the hole 16 so that the piston 14 can reciprocate in the hole 16. Further, the outer diameter D1 of the piston ring 14A is smaller than the diameter D2 of the diaphragm 13. Note that the diaphragm 13
In this embodiment, it is formed into a cup shape that bulges toward the fluid chamber side. By forming the diaphragm 13 in such a cup shape, the diaphragm 13 is simply curved in one direction and prevented from reversing.

The fluid chamber 17 is filled with a liquid such as oil or water or a gas such as air, but in order to smoothly and accurately transmit the movement of the piston 14 to the tire flamm 13, a fluid made of liquid is used. is preferable.

In this embodiment, the diaphragm 13 includes:
A biasing means 24 for biasing the diaphragm 13 toward the pump chamber 18 is provided.

As shown in FIG. 7, the biasing means 24 has a dish shape and has one end attached to the tire flamm 13 and a holding plate 101 which is sandwiched between the inner case and the outer case together with the diaphragm 13 in the liquid chamber 17. is fixed, extends toward the piston 14 through a through hole 102 provided in the center of the retaining plate 101, and has a cap body 103 attached to its tip, and both ends are held between the retaining plate 101 and the cap body. The diaphragm 13 is biased toward the liquid chamber 17 by the spring 105 which is inserted into the support rod 104 . Note that the surface of the holding plate 101 facing the diaphragm 13 is formed along the surface of the tire phragm 13 facing the liquid chamber 17, and determines the retreating position of the diaphragm 13 during the biasing. Note that the holding plate 101
A guide hole 106 through which liquid flows is provided through the hole.

The opposing rods 14a and 14b are oriented parallel to the pump shaft 7 with their lower ends facing toward the lower frame plate 2.
Fixed to 1. Note that the upper end is integrally joined by a frame member 45 below the upper frame plate 20 to increase its rigidity.

The outer case piece 44 also includes the pump chamber 18.
A check valve 15A that allows the paint to flow freely into the lower and upper vertical holes 46 and 47 leading to the , and a check valve 15 that allows the paint to freely flow out.
A valve body 15 consisting of B is arranged.

Furthermore, the outer ends of the upper vertical hole 47 and the lower vertical hole 46 are
Through-holes 4 are provided in the frame material 45 and the lower frame plate 21, respectively.
8 and 49.

The connecting means 19 for connecting the pump shaft 7 of the first pump body 2 and each rod 14a, 14b of the second pump body 3, as shown in FIGS. A screw shaft 55 arranged in a direction perpendicular to the shaft 7 and the rods 14a, 14b, and a movable fitting 56 screwed onto the screw shaft 55, one end of which engages with the pump shaft 7, thereby allowing the pump shaft 7 to move. It is provided with a lever-shaped connecting fitting 57 that swings about a fulcrum K on the movable fitting 56 along with the reciprocating movement, and whose other end is coupled to the rods 14a and 14b.

The screw shaft 55 has a straight shaft shape and is pivoted to the front and rear vertical pieces 72 and 73 rising from the lower frame plate 21 so as not to be able to move back and forth, so that it intersects perpendicularly with the pump shaft 7, etc. It is supported so that it can be rotated forward and backward depending on the direction. Further, the screw shaft 55 has a threaded portion 55A in the center portion located between the vertical pieces 72 and 73.
A handle 58 is provided at the distal end portion which projects forward from the front upright piece 72 and allows the screw shaft 55 to be rotated forward or backward by manual operation.

Note that the screw shaft 55 is attached to the front vertical piece 72.
A stopper 60 screwed into the front plate 59 disposed on the front side is pressed between the stopper 60 and the stopper 60 as the stopper 60 screws forward, thereby preventing rotation of the screw shaft 55 after setting.

Further, the movable fitting 56 has a rectangular block-shaped base body 56A that is screwed into the screw shaft 55, and the base body 56A has a rectangular block shape.
6A is prevented from rotating by a side plate piece 74 connecting between the vertical pieces 72 and 73, and is guided along the screw shaft 55. Therefore, the movable fitting 56 can be moved back and forth according to the rotation of the screw shaft 55, and the base body 56A has a supporting shaft 75 protruding from its upper surface on which a bearing piece 75A is rotatably inserted.

In this example, an indicator 76 is attached to indicate the amount of movement of the movable fitting 56, that is, the amount of position change of the fulcrum K, which is the axis of the support shaft 75. The indicator 76 includes a guide piece 77 having a guide groove 77A extending forward from near the front standing piece 72 and facing upward through the curved part, and a guide piece 77 having one end fixed to the upper surface of the movable fitting 56 and having a guide groove 77A. The guide piece 77 is fixed to the upper surface of the front plate 59, for example. The indicator piece 78 is made of a flexible elastic material such as a spring steel plate, and the other end is exposed from the guide piece 77, so that the amount of position change can be indicated by a change in the height position of the other end. . Note that the guide piece 77 has a scale formed in the exposed portion to quantify the amount of position change.

The connecting fitting 57 includes a pair of side frame pieces 80 that face parallel to the screw shaft 55 and sandwich the bearing piece 75A at the fulcrum K, and a connecting frame piece 81 that connects the vicinity of the front end and the rear end of the side frame pieces 80, respectively. , 82 in the shape of a horizontally long lever. In addition, the outer frame 85 is reinforced by the inner joint frame piece 83 arranged to be offset to the rear side, and the joint frame piece 82,
A support shaft body 87 that rotatably engages with the pump shaft 7 is fixed to a hole 86 surrounded by the side frame piece 83 and the side frame piece 80 .

The support shaft 87 has a support shaft portion inserted into a pivot hole 7A transparently provided at the center of the pump shaft 7 at the upper end of a block-shaped base 87A fitted into the hole 86. 8
7B is provided protrudingly, and the lower end of the base 87A is supported by a bottom plate 89 provided on the lower surface of the outer frame 85.

Therefore, the connecting fitting 57 engages with the pump shaft 7 at one end, which is the rear end, and the side frame pieces 80, 80 sandwich the bearing piece 75A, so that as the pump shaft 7 reciprocates, the support point K It can oscillate around the center.

[0045] The connecting fitting 57 also connects to the previous joint frame piece 81.
Upper and lower protruding pieces 90A and 90B are provided at each tip of the side frame piece 80 that protrudes forward from the upper and lower ends of the rods 14a and 14b, respectively, to sandwich the opposite ends of the rods 14a and 14b. Note that the protruding pieces 90A, 90B are formed by horizontally cutting the side frame piece 80, and in this example, as shown in FIG. 10, the protruding pieces 90A, 90B
The rods 14a, 14b are engaged with and driven by fitting the engagement pins 91, 91 upward and downward, which can come into contact with both sides. Therefore, in this example, the protruding pieces 90A, 90B and the engaging pin 91 form an engaging portion 90 that engages with each rod 14a, 14b.

As the connecting fitting 57 swings, the rods 14a and 14b move forward and backward in opposite directions. As the rod 14a moves forward, the piston 14 presses the liquid in the liquid chamber 17, and the movement of the liquid displaces the diaphragm 13 toward the pump chamber 18. As described above, since the outer diameter D1 of the piston 14 is larger than the diameter D2 of the diaphragm 13, the displacement δ1 of the diaphragm 13 and the displacement δ2 of the cylinder have the following formula: δ1=δ2×{(D1)2/( D
2) The relationship 2 } holds true. That is, the displacement of the diaphragm 13 can be reduced in proportion to the square of the ratio of the diameter D1 of the piston to the diameter D2 of the diaphragm, and therefore the flow rate passing through the pump chamber 18 can be finely adjusted.

Moreover, when the biasing means 24 having the above-mentioned configuration is provided, the diaphragm 13 can retreat without any time lag due to the biasing force when the piston 14 retreats, and the diaphragm 13 can accurately follow the movement of the piston 14. This will further stabilize the supply amount and allocation ratio.

The diaphragm pump device 1 has a stirrer 93 in the upper frame plate 20 that communicates with the through holes 35 and 48.
Paint containers 96A and 96B containing paints A and B, respectively, are connected to the through holes 36 and 49, respectively. Further, the agitator 93 includes a paint pressure regulator 97 having a pressure regulator between the pump body 2 and the agitator 93 to adjust the pressure of the paint A in the pump body 2 to a constant pressure, and one end 63A of which is connected to a first three-way valve 63 communicating with the agent feeder 62;
4A is interposed with a second three-way valve 64 communicating with the meter. Also, between the second pump body 3 on the driven side and the agitator 93, there is a third three-way valve 65 whose one end 65A communicates with the cleaning agent feeder 62, and a fourth valve whose one end 66A communicates with the meter. A three-way valve 66 is interposed between the first and third three-way valves 63,
The switching levers 65 and 65 are connected to each other by an operating handle 69, and the switching levers of the second and fourth three-way valves 64 and 66 are connected to each other by an operating handle 70 so that they can be switched integrally.

Therefore, by a combination of operations on the operation handles 69 and 70, the agitator 93 is removed from each pump body 2 and 3.
In addition to feeding the paints A and B into the interior, the paints A and B are taken out of the device from one end 64A and 66A for metering, and the paints A and B are transported from each pump body 2 and 3 to the stirrer 93. Cleaning of the agent flow path, cleaning of the flow path including the inside of the agitator 93, etc. can be conveniently performed with a single touch.

[0050]

Effects of the Invention As described above, the diaphragm device of the present invention, having the above-described configuration, can prevent the diaphragm from reversing, operate smoothly without generating vibration noise, and can operate the two pump bodies. It is possible to operate at an accurate ratio and at a high ratio, and it is possible to mix two liquids at a high ratio, and moreover, it is possible to greatly improve the mixing precision during mixing.

[Brief explanation of drawings]

FIG. 1 is a perspective view illustrating an embodiment of the present invention.

FIG. 2 is a sectional view showing a first pump body.

FIG. 3 is a perspective view showing the controller.

FIG. 4 is a sectional view showing the second pump body.

FIG. 5 is a sectional view showing the case body in a retracted state of the piston.

FIG. 6 is a sectional view showing the case body in a state where the piston is in an advanced state.

FIG. 7 is an exploded perspective view showing an example of a diaphragm biasing means.

FIG. 8 is a sectional view showing the connecting means.

FIG. 9 is an exploded perspective view thereof.

FIG. 10 is a perspective view showing a state in which the connecting fitting and the rod of the piston are connected.

FIG. 11 is a schematic diagram showing a state in which the first and second pump bodies are connected.

FIG. 12 is a sectional view showing a conventional technique.

[Explanation of symbols]

2 First pump body 3 Second pump body 5, 12 Cases 5a, 5b, 12a, 12b Case bodies 6, 13
Diaphragm 7 Pump shafts 8, 15 Valve bodies 8A, 8B, 15A, 15B Check valves 9, 16 Holes 10 Working chambers 11, 18 Pump chamber 14 Pistons 14a, 14b Rod 17 Fluid chamber 19 Connection means 24 Biasing means 56 Movement Metal fitting D1 Piston outer diameter D2 Diaphragm diameter H1, H2 Hole K Fulcrum

Claims (3)

[Claims] 1. A case comprising a pair of case bodies each having a cavity inside and having a hole communicating with the cavity, spaced apart from each other, with the holes facing inwardly, each of the cavities facing inside. a diaphragm that divides the diaphragm into a working chamber and an outer pump chamber; a pump shaft that fixes the diaphragm at both ends and is sealed and inserted through the hole; and a pump shaft that is electrically connected to the pump chamber and allows fluid to freely flow into the pump chamber. and a check valve that allows fluid to freely flow out of the pump chamber; A first pump body provided with an operating hole for reciprocating the pump shaft, and a pair of case bodies each having a cavity therein and a hole communicating with the cavity are spaced apart from each other and the hole is connected to the first pump body. a diaphragm that divides each of the cavities into an inner fluid chamber and an outer pump chamber; a piston that slides in the hole and causes fluid pressure in the fluid chamber to act on the diaphragm when moved forward; , and a valve body consisting of a check valve that communicates with the pump chamber and allows fluid to freely flow into the pump chamber, and a check valve that allows fluid to freely flow out from the pump chamber, a lever-shaped coupling means having a second pump body having a diameter smaller than the diameter of the diaphragm, and one end of which engages with the pump shaft to swing about a fulcrum with the reciprocating movement of the pump shaft; A diaphragm pump device in which each rod end of the piston is coupled to the other end. 2. The diaphragm pump device according to claim 1, wherein the fulcrum of the connecting means is provided on a movable fitting whose position is changed in the length direction of the connecting means. 3. The diaphragm pump device according to claim 1, wherein the diaphragm of the second pump body includes biasing means for biasing the diaphragm toward the liquid chamber.