CN217002448U

CN217002448U - Hydraulic feeding system

Info

Publication number: CN217002448U
Application number: CN202220524466.1U
Authority: CN
Inventors: 翟勇; 高燕
Original assignee: Mcc Mike Tianjin Hydraulic Technology Co ltd
Current assignee: Mcc Mike Tianjin Hydraulic Technology Co ltd
Priority date: 2022-03-11
Filing date: 2022-03-11
Publication date: 2022-07-19
Anticipated expiration: 2032-03-11

Abstract

The utility model relates to the field of hydraulic control and discloses a hydraulic feeding system. The utility model provides a nursing bed, which comprises a motor, oil, an oil tank, a plunger pump, a constant delivery pump, a servo electromagnetic valve and a servo cylinder, wherein the motor is connected with the oil tank; the oil is arranged in the oil tank, the oil tank is communicated with the plunger pump to form the plunger pump passage, the oil tank is communicated with the constant delivery pump to form the constant delivery pump passage, the motor can convey the oil to the plunger pump passage and the constant delivery pump passage, the constant delivery pump passage and the plunger pump passage are mutually independent, and the plunger pump passage and the constant delivery pump passage are both communicated with the servo cylinder through the servo solenoid valve; the fixed displacement pump passage is provided with a cut-off valve which can close the fixed displacement pump passage; the problem of current hydraulic system need install many sets of independent hydraulic system, cause the cost to rise is solved.

Description

Hydraulic feeding system

Technical Field

The utility model relates to the field of hydraulic control, in particular to a hydraulic feeding system.

Background

Under the background of present automatic mechanical control, a large number of servo cylinders are required to be used for automatic operation, and the servo cylinders are required to make complex automatic actions such as rapid stretching out or slow stretching out of accurate parameters.

In order to control a telescopic rod in a servo cylinder to extend in the prior art, a plunger pump is generally connected to an oil way of a hydraulic system communicated with the servo cylinder, and the servo cylinder is rapidly extended through a servo proportional valve connected to the hydraulic system; similarly, when the servo cylinder is required to slowly extend and give consideration to accurate extending distance, a constant delivery pump is required, and the extending action is also completed through the control of a servo proportional valve in the process;

however, the application scenarios that the servo cylinder needs to face are complex, the servo cylinder in one system corresponds to a single action and does not meet the requirement of diversification nowadays, when two different actions, namely quick extension and accurate extension positioning, are needed, two sets of independent hydraulic systems and two sets of servo proportional valves and motors are needed to be prepared and are respectively connected with the same servo cylinder, the servo cylinder is controlled to extend and retract by starting and stopping the motors under respective channels, or two servo levers in different motion states are directly used for control, and therefore the construction cost of the hydraulic systems can be increased.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a hydraulic system, so that the problem of cost increase caused by the fact that a plurality of sets of independent hydraulic systems need to be installed in the existing hydraulic system is solved.

In order to achieve the purpose, the utility model adopts the following technical scheme:

the utility model provides a hydraulic feeding system, which comprises a motor, an oil tank, a plunger pump, a fixed displacement pump, a servo electromagnetic valve and a servo cylinder, wherein the motor is connected with the oil tank;

the oil tank is used for respectively supplying oil to the plunger pump and the fixed displacement pump, the motor is used for driving the plunger pump and the fixed displacement pump to rotate, and the plunger pump and the fixed displacement pump both supply oil to the servo cylinder through the servo electromagnetic valve;

the hydraulic feeding system further comprises a cut-off valve, and the cut-off valve is used for communicating or disconnecting the output end of the fixed displacement pump with the oil tank.

Preferably, the servo cylinder comprises a cylinder body and a telescopic rod, the telescopic rod is inserted into the cylinder body, an accommodating cavity is formed in the cylinder body, and the telescopic rod divides the accommodating cavity into a rodless cavity and a rod cavity;

the servo electromagnetic valve comprises an oil inlet, an oil return opening, a first oil outlet and a second oil outlet, the oil inlet can be in switching communication with the first oil outlet and the second oil outlet, the oil return opening can be in switching communication with the first oil outlet and the second oil outlet, the output end of the constant delivery pump and the output end of the plunger pump are both communicated with the oil inlet, and the oil return opening is communicated with the oil tank;

the first oil outlet is communicated with the rodless cavity, and the second oil outlet is communicated with the rod cavity.

Preferably, the hydraulic feed system further includes a first check valve, the second oil outlet is communicated with the rod chamber through the first check valve, and the first check valve can prevent oil in the rod chamber from flowing back to the second oil outlet.

Preferably, the hydraulic feeder system further comprises a pressurizing passage capable of communicating the oil inlet and the rod chamber;

and a second check valve is arranged on the pressurizing passage and can prevent oil of the fixed displacement pump passage or the plunger pump from flowing to the rod cavity.

Preferably, the hydraulic feed system further comprises a third check valve configured to allow oil to flow only from the plunger pump to the oil inlet.

Preferably, the hydraulic control system further comprises a fourth check valve arranged between the third check valve and the oil inlet, and an accumulator arranged between the third check valve and the fourth check valve;

the fourth check valve rod chamber is configured to allow oil to flow only from the third check valve and the accumulator to the oil inlet.

Preferably, a fifth check valve is provided between the output end of the fixed displacement pump and the pressurizing passage;

the fifth check valve can prevent the rod chamber oil from flowing back to the fixed displacement pump from the pressurizing passage.

Preferably, the hydraulic feed system further comprises a first relief valve and a second relief valve; the output end of the plunger pump is communicated with the oil tank through the first overflow valve; and the output end of the constant delivery pump is communicated with the oil tank through the second overflow valve.

Preferably, the hydraulic feed system further comprises a filter, and the oil return port is communicated with the oil tank through the filter.

Preferably, the hydraulic feed system further comprises a hydraulic control check valve, one end of the hydraulic control check valve is connected with the rod cavity, and the other end of the hydraulic control check valve is connected with the first check valve and the second check valve respectively.

Has the advantages that: according to the utility model, two independent constant delivery pump passages and plunger pump passages are arranged in one hydraulic system, and the oil passages entering the servo electromagnetic valve are controlled by the cut-off valve, so that the action of slow and accurate extension or quick extension is realized.

Drawings

FIG. 1 is a schematic diagram of a hydraulic system of the present invention;

FIG. 2 is an enlarged view of the servo solenoid valve of the present invention.

In the figure: 1-an electric motor; 2-oil liquid; 3-an oil tank; 4-a plunger pump; 5-a fixed displacement pump; 6-servo electromagnetic valve; 61-oil inlet; 62-oil return port; 63-a first oil outlet; 64-a second oil outlet; 7-a servo cylinder; 71-a telescopic rod; 72-rodless cavity; 73-rod cavity; 8-a shut-off valve; 9-a first one-way valve; 10-a second one-way valve; 11-a third one-way valve; 12-a fourth one-way valve; 13-a fifth one-way valve; 14-an accumulator; 15-a first overflow valve; 16-a second overflow valve; 17-a filter; 18-a first pressure relay; 19-a second pressure relay; 20-a liquid level meter; 21-a hydraulic relay; 22-a temperature sensor; 23-air filter; 24-a pilot operated check valve; 25-air cooler; 26-a reversing valve; 27-exhaust start valve.

Detailed Description

The present invention will be described in further detail with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the utility model and are not limiting of the utility model. It should be further noted that, for the convenience of description, only some structures related to the present invention are shown in the drawings, not all of them.

In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the present invention, unless expressly stated or limited otherwise, the recitation of a first feature "on" or "under" a second feature may include the recitation of the first and second features being in direct contact, and may also include the recitation that the first and second features are not in direct contact, but are in contact via another feature between them. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

In the description of the present embodiment, the terms "upper", "lower", "right", etc. are used in an orientation or positional relationship based on that shown in the drawings only for convenience of description and simplicity of operation, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used only for descriptive purposes and are not intended to have a special meaning.

The rotary motion of the motor 1 is converted into the linear motion of the telescopic rod 71 in the servo cylinder 7 by the servo cylinder 7 through the conduction of the pump body and hydraulic oil, a hydraulic feeding system in the prior art can only meet one action requirement of the servo cylinder 7, the plunger pump 4 is arranged in the hydraulic feeding system in the servo cylinder 7, the telescopic rod 71 in the servo cylinder 7 can be rapidly extended, and similarly, if the plunger pump 4 is replaced by the fixed displacement pump 5, due to the self characteristics of the fixed displacement pump 5, the telescopic rod 71 in the servo cylinder 7 can be flexibly positioned at an accurate distance, and the accurate distance control of the telescopic rod 71 is realized.

However, such a hydraulic feeding system can only control one action of the telescopic rod 71 in the servo cylinder 7, and because the current corresponding working condition is more complicated, the telescopic rod 71 is often required to perform a plurality of working conditions, so that the plunger pump 4 and the fixed displacement pump 5 respectively form an independent hydraulic system, and the extension mode of the telescopic rod 71 in the servo cylinder 7 is controlled by starting and stopping the two motors 1 in the respective systems; when two independent hydraulic systems are provided, the same parts are used for building the system, for example, two servo electromagnetic valves 6 and two groups of motors 1 are needed to control the servo cylinders 7 respectively, so that the cost for building the hydraulic feeding system is increased, and the difficulty of subsequent maintenance is increased.

As shown in fig. 1, in the utility model, by improving the hydraulic feeding system, the plunger pump 4 and the constant delivery pump 5 are simultaneously controlled by the servo solenoid valve 6 and the single motor 1 to control the hydraulic telescopic rod 71 in the single hydraulic feeding system, so that the practical number of hydraulic components is reduced, and the use cost for building the hydraulic system is reduced.

Optionally, the motor 1 is connected in series with the plunger pump 4 and the fixed displacement pump 5, when the motor 1 rotates, the plunger pump 4 and the fixed displacement pump 5 are driven to rotate simultaneously, and then the plunger pump 4 and the fixed displacement pump 5 which are communicated with the oil tank 3 can input hydraulic oil into a pipeline, because the oil pressure of the fixed displacement pump 5 under the working condition is far higher than that of the plunger pump 4, when hydraulic oil on the plunger pump 4 and the fixed displacement pump 5 is collected to a pipeline at the front end of the oil inlet 61, the oil inlet 61 is pushed out by a low-pressure oil way through a high-pressure oil way, so that the hydraulic oil entering the oil inlet 61 is all high-pressure oil on the fixed displacement pump 5.

Optionally, when the oil 2 requiring the passage of the plunger pump 4 enters the oil inlet 61, the block valve 8 on the passage of the fixed displacement pump 5 needs to be opened to prevent the hydraulic oil of the passage of the fixed displacement pump 5 from flowing to the oil inlet 61, and at this time, the oil 2 flowing to the oil inlet 61 only comes from the low-pressure oil 2 on the passage of the plunger pump 4.

The quantitative pump 5 passage and the plunger pump 4 passage are communicated with the servo cylinder 7 through the servo solenoid valve 6, and compared with a traditional hydraulic passage, the hydraulic control system can save the servo solenoid valve 6 and a matched pipeline, and reduce the assembly cost and the later maintenance cost.

As shown in fig. 1, the servo cylinder 7 comprises a cylinder body and an expansion rod 71, the expansion rod 71 is inserted into the cylinder body, an accommodating cavity is formed in the cylinder body, and the expansion rod 71 divides the cylinder body into a rodless cavity 72 and a rod cavity 73; the servo solenoid valve 6 comprises an oil inlet 61, an oil return port 62, a first oil outlet 63 and a second oil outlet 64, the oil inlet 61 is respectively communicated with the first oil outlet 63 and the second oil outlet 64, the first oil outlet 63 and the second oil outlet 64 are respectively communicated with the oil return port 62, and the oil return port 62 is communicated with the oil tank 3; said first outlet port 63 communicates with said rodless chamber 72 and said second outlet port 64 communicates with said rod chamber 73.

The passage of the fixed displacement pump 5 and the passage of the plunger pump 4 can respectively convey the oil 2 to an oil inlet 61 of the servo solenoid valve 6, and the oil inlet 61 in the servo solenoid valve 6 can enable a first oil outlet 63 of the oil inlet 61 to be communicated or be communicated with a second oil outlet 64 through an electric control system carried by the oil inlet 61; in the process of extending the telescopic rod 71 in the servo cylinder 7, the oil inlet 61 needs to be communicated with the first oil outlet 63, so that the oil liquid 2 can be conveyed into the rodless cavity 72 communicated with the first oil outlet 63, and when the rodless cavity 72 is filled with the oil liquid 2, the oil liquid 2 can push the telescopic rod 71 to move outwards, so that the extending effect is achieved;

both the fixed displacement pump 5 passage and the plunger pump 4 passage need to deliver the oil 2 into the rodless cavity 72 to achieve the effect of extending the telescopic rod 71 in the servo cylinder 7.

When the telescopic rod 71 needs to retract inwards, the oil inlet 61 is communicated with the second oil outlet 64 to convey hydraulic oil in the oil tank 3 to the rod cavity 73, so that the hydraulic oil in the rod cavity 73 is increased, the oil 2 pushes the telescopic rod 71 to be retracted, and meanwhile, the oil 2 in the rod-free cavity 72 is communicated with the oil return port 62 to convey the extruded oil 2 to the oil tank 3.

As shown in fig. 1, the hydraulic feed system further includes a first check valve 9, the second oil outlet 64 communicates with the rod chamber 73 through the first check valve 9, and the first check valve 9 can prevent the oil 2 from flowing back to the second oil outlet 64.

When the telescopic rod 71 extends outwards, the oil 2 flowing out of the rod cavity 73 cannot pass through the first check valve 9, so that all the oil 2 flowing out of the rod cavity 73 can enter a pressurizing passage, the oil 2 entering the oil inlet 61 is supplemented, and the extending action of the telescopic rod 71 is quicker.

As shown in fig. 1, the rod chamber 73 is further communicated with the oil inlet 61 to form a pressurizing passage, a second check valve 10 is disposed on the pressurizing passage, and the second check valve 10 can prevent the oil 2 in the fixed displacement pump 5 and the oil 2 in the plunger pump 4 from flowing to the rod chamber 73.

When first check valve 9 will have fluid 2 shutoff in the pole chamber 73 to block up, second check valve 10 can let above-mentioned fluid 2 pass through to because the pressurized access is direct to be connected with oil inlet 61, will be extruded have fluid 2 backward flow in pole chamber 73 to be carried to oil inlet 61, make the fluid 2 that gets into oil inlet 61 come from having pole chamber 73 and oil tank 3 respectively, the entering has the 2 volumes of fluid in pole chamber 73 to be big more, the projecting speed of telescopic link 71 is faster.

As shown in fig. 1, the plunger pump 4 on the hydraulic feeding system is further connected to the accumulator 14, when the hydraulic feeding system is powered off, the accumulator 14 can release the oil 2 stored inside the accumulator 14, so that the hydraulic feeding system can continue to work to cope with sudden situations, and the oil 2 in the accumulator 14 can make the telescopic rod 71 in the servo cylinder 7 retract or extend once, so that the instrument connected to the telescopic rod 71 of the servo cylinder 7 can be restored to a safe working state.

As shown in fig. 1, the hydraulic feeding system further includes the third check valve 11, when the hydraulic feeding system is powered off, the accumulator 14 starts to operate, and the third check valve 11 can prevent the oil 2 flowing from the accumulator 14 to the oil inlet 61 from flowing back to the plunger pump 4.

Optionally, the third check valve 11 can also prevent the oil 2 in the passage of the plunger pump 4 from flowing back to the plunger pump 4, so as to protect the plunger pump 4 from being damaged, and control the oil 2 in the passage of the energy accumulator 14 and the plunger pump 4 to flow to the oil inlet 61 completely.

As shown in fig. 1, the plunger pump 4 is provided with the fourth check valve 12, and the fixed displacement pump 5 is provided with the fifth check valve 13; the fourth check valve 12 prevents the pressurized path oil 2 from flowing back to the accumulator 14, and the fifth check valve 13 prevents the pressurized path oil 2 from flowing back to the fixed displacement pump 5.

The fourth check valve 12 and the fifth check valve 13 are arranged in opposite directions on two sides of the oil inlet 61 and the pressurizing passage, so that the oil 2 passing through the pressurizing passage has only one inlet of the oil inlet 61, and the fourth check valve 12 and the fifth check valve 13 can enable the oil 2 in the rod chamber 73 to completely flow back to the rodless chamber 72, so that the input amount of the oil 2 in the rodless chamber 72 is ensured to be maximum, and the extending speed of the telescopic rod 71 is also ensured to be maximum.

As shown in fig. 1, the hydraulic feed system further includes a first overflow valve 15 and a second overflow valve 16, the first overflow valve 15 is connected to the plunger pump 4 passage, when the metering pump 5 passage delivers the oil 2 to the oil inlet 61, the pressure in the plunger pump 4 passage will continuously rise, in order to prevent the passage from breaking, the first overflow valve 15 is arranged on the plunger pump 4 passage, and when the pressure in the plunger pump 4 passage reaches a set value, the first overflow valve 15 will open, so that the oil 2 in the plunger pump 4 is maintained at a lower level; when the cut-off valve 8 closes the passage of the fixed displacement pump 5, the pressure in the passage of the fixed displacement pump 5 also increases with time, the second overflow valve 16 is connected to the passage of the fixed displacement pump 5, and when the pressure in the passage of the fixed displacement pump 5 reaches a set value, the second overflow valve 16 is opened, so that the pressure of the oil 2 in the passage of the fixed displacement pump 5 can be prevented from increasing.

Optionally, a first pressure relay 18 is further installed on a passage where the first oil outlet 63 is connected to the rodless chamber 72, the first pressure relay 18 may detect whether the pressure in the rodless chamber 72 is within a normal range, and correspondingly, a second pressure relay 19 is also installed on a passage where the rod chamber 73 is connected, and may also detect the pressure in the rod chamber 73, thereby ensuring that the pressure in the rod chamber 73 is within a normal range of values.

Optionally, before the oil liquid 2 flows back to the oil tank 3 from the oil return port 62, the oil liquid 2 needs to pass through the filter 17, and the filter 17 can filter out impurities in the oil liquid 2, so that the oil liquid 2 flowing back to the oil tank 3 is kept clean.

Optionally, still be provided with level gauge 20 and hydraulic relay 21 on the lateral wall of oil tank 3, level gauge 20 can let the staff directly observe the 2 height of fluid in the oil tank 3 from 3 lateral walls of oil tank, and hydraulic relay 21 can observe the 2 liquid level positions of fluid in the oil tank 3, makes fluid 2 maintain within reasonable scope.

Optionally, a temperature sensor 22 and an air filter 23 are further arranged in the oil tank 3, when the hydraulic system works, the temperature of the oil 2 rises, so that the temperature sensor 22 is needed to feed back the height of the oil 2 in the oil tank 3, and after the temperature rises abnormally, the air cooler 25 is opened to reduce the temperature of the oil 2.

Optionally, a pilot check valve 24 is further connected to the outer side of the rod chamber 73, and the pilot check valve 24 has one more pilot oil path, and when the pilot oil path is not connected to the pressure oil 2, the pilot oil path cannot flow in the reverse direction, so that the telescopic rod 71 does not extend, and the pipeline rupture pressure is generally insufficient in this case. When the pressure in the pipeline is within a normal range, the oil inlet and the oil outlet are communicated, the hydraulic control one-way valve 24 is opened, the telescopic rod 71 can normally extend out, the hydraulic system controls the hydraulic control one-way valve 24 to be opened and closed through the reversing valve 26, the exhaust starting valve 27 is further arranged, and the exhaust starting valve 27 can exhaust redundant gas in the pipeline of the system in the process of switching the hydraulic feeding system from closing to running, so that the gas is prevented from entering the rod cavity 73 or the rodless cavity 72.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Numerous obvious variations, adaptations and substitutions will occur to those skilled in the art without departing from the scope of the utility model. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A hydraulic feeding system comprises a motor (1), an oil tank (3), a plunger pump (4), a fixed displacement pump (5), a servo electromagnetic valve (6) and a servo cylinder (7);

the oil tank (3) is used for respectively supplying oil to the plunger pump (4) and the fixed displacement pump (5), and the motor (1) is used for driving the plunger pump (4) and the fixed displacement pump (5) to rotate, and the oil pump is characterized in that the plunger pump (4) and the fixed displacement pump (5) supply oil to the servo cylinder (7) through the servo electromagnetic valve (6);

the hydraulic feeding system further comprises a cut-off valve (8), and the cut-off valve (8) is used for communicating or disconnecting the output end of the constant delivery pump (5) with the oil tank (3).

2. The hydraulic feed system according to claim 1, characterized in that said servo cylinder (7) comprises a cylinder body and an expansion rod (71), said expansion rod (71) being inserted in said cylinder body, said cylinder body forming a housing chamber, said expansion rod (71) dividing said housing chamber into a rodless chamber (72) and a rod chamber (73);

the servo electromagnetic valve (6) comprises an oil inlet (61), an oil return port (62), a first oil outlet (63) and a second oil outlet (64), the oil inlet (61) can be communicated with the first oil outlet (63) and the second oil outlet (64) in a switching mode, the oil return port (62) can be communicated with the first oil outlet (63) and the second oil outlet (64) in a switching mode, the output end of the quantitative pump (5) and the output end of the plunger pump (4) are communicated with the oil inlet (61), and the oil return port (62) is communicated with the oil tank (3);

the first outlet port (63) is in communication with the rodless chamber (72), and the second outlet port (64) is in communication with the rod chamber (73).

3. The hydraulic feed system according to claim 2, characterized in that it further comprises a first non-return valve (9), said second outlet port (64) communicating with said rod chamber (73) through said first non-return valve (9), said first non-return valve (9) being able to prevent the oil (2) inside said rod chamber (73) from flowing back to said second outlet port (64).

4. The hydraulic feed system according to claim 2, characterized in that it further comprises a pressurized passage able to communicate the oil inlet (61) and the rod chamber (73);

and a second check valve (10) is arranged on the pressurizing passage, and the second check valve (10) can prevent the oil (2) of the fixed displacement pump (5) passage or the plunger pump (4) from flowing to the rod cavity (73).

5. The hydraulic feed system of claim 4, further comprising a third check valve (11), the third check valve (11) being configured to allow oil to flow from the plunger pump (4) to the oil inlet (61) only.

6. The hydraulic feed system according to claim 5, further comprising a fourth check valve (12) disposed between the third check valve (11) and the oil inlet (61), and an accumulator (14) disposed between the third check valve (11) and the fourth check valve (12);

the fourth check valve (12) has a rod chamber configured to allow oil to flow only from the third check valve (11) and the accumulator (14) to the oil inlet (61).

7. Hydraulic feed system according to claim 4, characterized in that a fifth non return valve (13) is arranged between the output of the fixed displacement pump (5) and the pressurizing passage;

the fifth check valve (13) prevents oil in the rod chamber (73) from flowing back from the pressurizing passage to the fixed displacement pump (5).

8. The hydraulic feed system according to claim 1, characterized in that it further comprises a first overflow valve (15) and a second overflow valve (16);

the output end of the plunger pump (4) is communicated with the oil tank (3) through the first overflow valve (15);

the output end of the fixed displacement pump (5) is communicated with the oil tank (3) through the second overflow valve (16).

9. Hydraulic feed system according to claim 2, characterised in that it further comprises a filter (17), the return (62) being in communication with the tank (3) through the filter (17).

10. The hydraulic feed system according to claim 2, characterized in that it further comprises a pilot operated check valve (24), one end of the pilot operated check valve (24) being connected to said rod chamber (73) and the other end being connected to the first check valve (9) and the second check valve (10), respectively.