JP7339883B2 - Air bubble content adjustment system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a bubble content adjustment system for adjusting the content of bubbles in a liquid.

Patent Document 1 discloses a bubble separator that separates the oil into a first oil from which bubbles have been removed and a second oil containing bubbles by using a swirling flow of oil flowing in from a main tank; Disclosed is a liquid bubble separation/removal circulation system having a sub-tank that incorporates a plurality of partition plates and a plurality of filters, and captures, binds, and releases bubbles contained in the inflowed second oil. In this system, the oil in the main tank is pressurized by a pump through the first pipe and supplied to the air separator, and the first oil separated by the air separator is sent through the second pipe. Return it to the main tank, let the second oil flow into the sub-tank via the third pipe, and return the third oil from which air bubbles have been removed in the sub-tank to the main tank via the fourth pipe. there is

JP 2013-192990 A

In general, if the hydraulic fluid used to operate the hydraulic equipment contains a large amount of air bubbles, cavitation and deterioration of the hydraulic fluid tend to occur, resulting in a decrease in the operating performance of the hydraulic equipment. . Therefore, it is desirable to remove air bubbles in the working fluid using an air bubble removing device such as that disclosed in Japanese Unexamined Patent Application Publication No. 2002-200012.

On the other hand, some hydraulic devices are used in an environment where air bubbles are likely to be mixed in the hydraulic fluid or in an environment where it is difficult to remove air bubbles with a bubble removing device. Therefore, in evaluating the performance of such hydraulic equipment, it is desirable to evaluate the performance in a state in which air bubbles are mixed to some extent in accordance with the environment in which the equipment is used.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bubble content adjustment system capable of adjusting the content of bubbles in a liquid.

The present invention is an air bubble content adjustment system comprising a circulation passage for circulating liquid between a tank and a pump, a bubble removal device provided in the circulation passage for removing air bubbles in the liquid, and a liquid flowing through the circulation passage. a bubble mixing device for introducing bubbles into the liquid flowing through the circulation passage, a measuring device for measuring the content of bubbles in the liquid flowing through the circulation passage, and a controller for adjusting the content of bubbles in the liquid; a discharge passage for guiding the liquid discharged from to the bubble removing device, a discharge passage for guiding the liquid from which bubbles have been removed by the bubble removing device, and a discharge passage for discharging the bubbles removed by the bubble removing device; The bubble removing device has a control valve for controlling the flow rate of at least one of the liquid passing through the lead-out passage and the liquid passing through the discharging passage, and the controller controls the control valve of the bubble removing device and the It is characterized by controlling the operation of the bubble mixing device.

In the present invention, the air bubble content in the liquid is increased or decreased by controlling the operation of the air bubble mixing device for increasing the air bubble content in the liquid and the air bubble removing device for decreasing the air bubble content in the liquid. can be done.

Moreover, in the present invention, the control valve is provided in each of the lead-out passage and the discharge passage.

In the present invention, since both the flow rate of the liquid with bubbles removed and passing through the lead-out passage and the flow rate of the liquid containing the removed bubbles and passing through the discharge passage are controlled, The degree of freedom in adjusting the amount is improved.

Also, in the present invention, the measurement device measures the air bubble content of the hydraulic oil discharged from the pump, passed through the air bubble removal device, and led to the tank.

In the present invention, the measuring device measures the bubble content of the liquid drawn into the pump through the bubble eliminator, rather than the liquid discharged from the pump and directed to the bubble eliminator. Therefore, even if air bubbles are generated inside the pump, the air bubbles are removed from the liquid by the air bubble removing device accordingly. The content can be controlled to a desired value.

According to the invention, the content of air bubbles in the liquid can be adjusted.

1 is a hydraulic circuit diagram showing an air bubble content adjustment system according to an embodiment of the present invention; FIG. 1 is a block diagram showing the configuration of a bubble content adjustment system according to an embodiment of the present invention; FIG. FIG. 4 is a cross-sectional view showing the pipe line portion of the bubble removing device according to the embodiment of the present invention; FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3; FIG. 4 is a hydraulic circuit diagram showing a modified example of the air bubble content adjustment system according to the embodiment of the present invention;

A bubble content adjustment system 100 according to an embodiment of the present invention will be described below with reference to the drawings.

The air bubble content adjustment system 100 is used, for example, in a performance evaluation system 1 that performs a performance evaluation test of a hydraulic device (hydraulic device) to be evaluated.

As shown in FIG. 1 , the air bubble content adjustment system 100 includes a circulation passage 10 in which hydraulic fluid as a liquid circulates, a tank 20 provided in the circulation passage 10 for storing the hydraulic fluid, and an operating fluid stored in the tank 20 . A hydraulic pump 30 as a pump that sucks and discharges oil and circulates the hydraulic oil in the circulation passage 10; a bubble removing device 40 that is provided in the circulation passage 10 and removes bubbles in the hydraulic oil; A bubble mixing device 60 for adding bubbles to the oil, a measuring device 70 for measuring the content of bubbles in the hydraulic oil flowing through the circulation passage 10, and a controller 80 for adjusting the content of bubbles in the hydraulic oil (Fig. 2). See) and

The hydraulic pump 30 is rotationally driven by an electric motor (not shown), sucks hydraulic oil from the tank 20 through the suction passage 11 , pressurizes the sucked hydraulic oil, and discharges it through the discharge passage 12 . Hydraulic pump 30 is, for example, a vane pump. In this embodiment, the hydraulic pump 30 is a hydraulic device to be evaluated in the performance evaluation test. That is, in the present embodiment, the pump as the hydraulic equipment to be evaluated by the performance evaluation system 1 and the pump in the air bubble content adjustment system 100 are used in common. The discharge passage 12 is provided with an evaluation measurement device 2 that collects information for evaluating the performance of the hydraulic pump 30 .

The air bubble removing device 40 includes a discharge passage 12 for guiding hydraulic oil discharged from the hydraulic pump 30, an outlet passage 13 for guiding hydraulic oil from which bubbles have been removed, and a discharge passage 14 for discharging the removed bubbles. , are connected.

The lead-out passage 13 and the discharge passage 14 are each connected to the tank 20 . A measuring device 70 is provided in the lead-out passage 13 . A sub-tank 21 is provided in the discharge passage 14 . A circulation passage 10 is configured by the intake passage 11 , the discharge passage 12 , the discharge passage 13 and the discharge passage 14 .

The air bubble removing device 40 includes a pipeline portion 41 for separating and removing air bubbles from hydraulic oil, and a first control valve 50 (control valve) provided in the lead-out passage 13 for controlling the flow rate of the hydraulic oil passing through the lead-out passage 13. and a second control valve 55 (control valve) that is provided in the discharge passage 14 and controls the flow rate of hydraulic oil passing through the discharge passage 14 .

As shown in FIG. 3, the air bubble removing device 40 generates a swirling flow in the fluid pressure chamber 42 formed by the pipe line portion 41, and utilizes the centrifugal force of the swirling flow to separate and remove the working oil and the air bubbles. It is a so-called cyclone type (centrifugal separation type).

The pipe line portion 41 includes a first pipe line portion 43 having a predetermined first inner diameter D1 and a second pipe portion 44 having a second inner diameter D2 smaller than the first inner diameter D1. , a tapered pipeline portion 45 that connects the first pipeline portion 43 and the second pipeline portion 44 and whose inner diameter gradually decreases from the first inner diameter D1 to the second inner diameter D2; and a communicating vent port 46 . The first pipeline portion 43, the second pipeline portion 44, the tapered pipeline portion 45, and the vent port 46 are formed coaxially with each other. The first pipeline portion 43 and the second pipeline portion 44 are straight pipelines each having a constant inner diameter in the axial direction.

As shown in FIGS. 3 and 4, the first pipeline portion 43 is connected to a pair of inflow ports 47a and 47b for guiding hydraulic fluid along the tangential direction. The pair of inflow ports 47 a and 47 b communicate with the discharge passage 12 and are provided at positions symmetrical to each other with respect to the central axis of the first pipe line portion 43 . In addition, in FIG. 3, one inflow port 47b is schematically represented by a dashed line.

The second pipeline portion 44 communicates with the lead-out passage 13, as shown in FIG. The tapered pipe line portion 45 has an inner peripheral surface formed in a tapered surface shape (conical surface shape). The vent port 46 communicates with the discharge passage 14 and opens inside the first pipe line portion 43 from the side opposite to the tapered pipe line portion 45 in the axial direction. The inner diameter of the vent port 46 is formed smaller than the second inner diameter D2.

Hydraulic oil discharged from the hydraulic pump 30 flows from the discharge passage 12 through the pair of inflow ports 47a and 47b into the first pipe line portion 43 from the tangential direction of the first pipe line portion 43, as shown in FIG. do. As a result, a swirling flow is generated around the central axis of the pipeline portion 41 in the fluid pressure chamber 42 inside the pipeline portion 41 (see the arrow in FIG. 4).

Due to the centrifugal force of the swirling flow generated in the fluid pressure chamber 42 , the hydraulic fluid is collected on the inner circumference of the pipeline portion 41 (the inner wall of the fluid pressure chamber 42 ), and the air bubbles contained in the hydraulic fluid are collected at the center of the pipeline portion 41 . Collected near the axis. In this way, air bubbles are separated from the hydraulic fluid. Hydraulic oil collected on the inner periphery of the pipe line portion 41 by the centrifugal force of the swirling flow is guided by the inner peripheral surface of the tapered pipe line portion 45 from the first pipe line portion 43 to the second pipe line portion 44 side. (See Figure 3). Therefore, the hydraulic fluid from which bubbles are separated is guided from the second pipe line portion 44 to the lead-out passage 13 .

Also, since the second inner diameter D2 of the second pipeline portion 44 is smaller than the first inner diameter D1 of the first pipeline portion 43, back pressure is generated in the tapered pipeline portion 45 due to the decrease in the flow path diameter. Due to this back pressure, air bubbles collected near the central axis are discharged from the discharge passage 14 through the vent port 46 together with part of the hydraulic fluid.

In this manner, the air bubble removing device 40 separates air bubbles from the hydraulic oil, guides the air bubble-removed hydraulic oil to the lead-out passage 13, and removes air bubbles (strictly speaking, hydraulic oil containing many air bubbles) from the discharge passage. 14 is discharged.

The first control valve 50 and the second control valve 55 are, as shown in FIG. 1, proportional solenoid valves whose opening areas change proportionally according to the amount of power supplied to the solenoids 51 and 56, respectively.

The first control valve 50 is provided in the lead-out passage 13 between the pipeline portion 41 and the measuring device 70 . The first control valve 50 is switched from a blocking position 50A that blocks the lead-out passage 13 to an open position 50B that opens the lead-out passage 13 as the amount of electricity supplied to the solenoid 51 increases. More specifically, the first control valve 50 moves the valve element (not shown) to a position where the electromagnetic force generated by the energization of the solenoid 51 and the spring force of the spring 52, which is the biasing member, is balanced. The valve is opened to the open position 50B with an opening area (opening degree) according to the position of the body. The first control valve 50 changes the opening area according to the amount of electricity supplied to the solenoid 51, thereby controlling the flow rate of the hydraulic oil passing through, that is, the flow rate of the hydraulic oil passing through the lead-out passage 13 after air bubbles are removed. do. When the solenoid 51 is deenergized, the first control valve 50 assumes a shutoff position 50A that shuts off the lead-out passage 13 by the biasing force of the spring 52 .

A second control valve 55 is provided in the discharge passage 14 between the pipeline portion 41 and the sub-tank 21 . As with the first control valve 50, the second control valve 55 is switched from a blocking position 55A that blocks the discharge passage 14 to an opening position 55B that opens the discharge passage 14 as the amount of electricity supplied to the solenoid 56 increases. . In the second control valve 55, the valve body (not shown) moves to a position where the electromagnetic force generated by the energization of the solenoid 56 and the spring force of the spring 57, which is an urging member, is balanced, and the valve body is adjusted accordingly. The valve is opened so that the opening area (opening degree) is at the open position 55B. The second control valve 55 changes the opening area according to the amount of power supplied to the solenoid 56 , thereby controlling the flow rate of the hydraulic fluid containing the separated air bubbles that is discharged to the sub-tank 21 through the discharge passage 14 . When the solenoid 56 is deenergized, the second control valve 55 also assumes a shutoff position 55A that shuts off the discharge passage 14 by the biasing force of the spring 57 .

The bubble mixing device 60 has a pair of gears 61a and 61b that are provided in the tank 20 and mesh with each other, and an electric motor 62 (see FIG. 2) that drives one gear 61a to rotate. The gears 61 a and 61 b are rotationally driven by the electric motor 62 , thereby agitating the hydraulic oil stored in the tank 20 and containing air bubbles in the hydraulic oil in the tank 20 . The faster the electric motor 62 rotates, the more the hydraulic oil in the tank 20 is agitated and the more air bubbles are contained in the hydraulic oil.

The measuring device 70 measures the bubble content in the hydraulic oil at predetermined time intervals (sampling period). The bubble oil content in the hydraulic oil measured by the measuring device 70 (hereinafter referred to as "actual oil content") is input to the controller 80 (see FIG. 2). Since the measuring device 70 can employ a known device for measuring the air bubble content in the hydraulic oil, a detailed description thereof will be omitted.

The controller 80 is composed of a microcomputer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an I/O interface (input/output interface). The RAM stores data in CPU processing, the ROM stores CPU control programs and the like in advance, and the I/O interface is used to input/output information with connected devices. Controller 80 may be composed of a plurality of microcomputers. The controller 80 is programmed so as to be able to execute at least the processing necessary for the control according to this embodiment and the modification. Note that the controller 80 may be configured as a single device, or may be divided into a plurality of devices so that each control in the present embodiment is distributed and processed by the plurality of devices.

Next, operation of the air bubble content adjustment system 100 will be described.

The hydraulic oil in the tank 20 is stirred by the bubble mixing device 60 and is kept in a state in which bubbles are contained to some extent. Further, the hydraulic pump 30 is rotationally driven at a constant speed, and sucks and discharges hydraulic oil containing air bubbles from the tank 20 . The pressure, flow rate, etc. of the hydraulic oil discharged from the hydraulic pump 30 are measured by the evaluation/measurement device 2 , and the performance of the hydraulic pump 30 is evaluated based on the measurement results of the evaluation/measurement device 2 . A well-known method can be adopted for the performance evaluation method of the hydraulic pump 30, so detailed description thereof will be omitted.

Hydraulic oil discharged from the hydraulic pump 30 is guided to the bubble removing device 40 . A portion of the hydraulic oil guided to the bubble removing device 40 is separated from bubbles by the conduit section 41 and guided to the measuring device 70 through the lead-out passage 13 and the first control valve 50, and the rest is separated by the conduit section 41. It is discharged to the sub-tank 21 through the discharge passage 14 and the second control valve 55 together with the generated bubbles. The ratio of the flow rate of the hydraulic fluid guided to the lead-out passage 13 and the hydraulic fluid guided to the discharge passage 14 is determined according to the opening degrees of the first control valve 50 and the second control valve 55 . That is, the amount of air bubbles separated from the hydraulic fluid and discharged (removed) to the sub-tank 21 is determined according to the opening degrees of the first control valve 50 and the second control valve 55 .

Hydraulic oil that contains air bubbles and is led to the sub-tank 21 is stored in the sub-tank 21 . By storing the hydraulic oil in the sub-tank 21, air bubbles contained in the hydraulic oil are released into the atmosphere. Hydraulic oil from which air bubbles have been released is guided to the tank 20 through the discharge passage 14 .

Hydraulic oil guided from the bubble removing device 40 to the measuring device 70 is measured for bubble content by the measuring device 70 . Hydraulic oil that has passed through the measuring device 70 is led to the tank 20 , stirred by the air bubble mixing device 60 in the tank 20 , and then sucked into the hydraulic pump 30 while containing air bubbles again.

In the air bubble content adjustment system 100 as described above, the air bubble content of the hydraulic oil in the circulation passage 10 is mainly determined by the amount of air bubbles contained by the air bubble mixing device 60 and the amount of air bubbles removed by the air bubble removing device 40. , determined by Therefore, in the present embodiment, the controller 80 controls the operation of the air bubble mixing device 60 that increases the air bubble content in the hydraulic oil and the air bubble removal device 40 that lowers the air bubble content in the hydraulic oil. Adjust the air bubble content of the hydraulic oil in 10 to the desired value. A method for adjusting the bubble content will be described below.

The controller 80 controls the operation of the electric motor 62 of the bubble mixing device 60 and the first control valve 50 and the second control valve 55 of the bubble removing device 40 to adjust the bubble content of the hydraulic oil flowing through the circulation passage 10. do.

The operation of the electric motor 62 of the bubble mixing device 60 is controlled so as to rotate at a constant speed. As a result, a certain amount of air bubbles are contained in the hydraulic oil in the tank 20 by the air bubble mixing device 60 .

The first control valve 50 is feedback-controlled according to the amount of air bubbles in the hydraulic fluid input from the measuring device 70 . The second control valve 55 is controlled to be switched to the open position 55B at a predetermined degree of opening and to maintain that degree of opening.

Feedback control of the first control valve 50 will be described below.

The controller 80 stores a preset target value for the air bubble content in the hydraulic oil (hereinafter referred to as "target content"). When the data of the actual content in the hydraulic oil is input from the measuring device 70, the controller 80 feeds back the operation of the first control valve 50 of the bubble removing device 40 so that the actual content matches the target content. Control. In this way, the measurement time interval of the measuring device 70 and the control time interval of the controller 80 are configured to match.

Specifically, when data of the actual content is input from the measuring device 70, the controller 80 subtracts the actual content from the target content to calculate the deviation between the target content and the actual content. The controller 80 multiplies the calculated deviation by a predetermined gain value to calculate a command current value for the solenoid 51 of the first control valve 50 . The controller 80 increases or decreases the energization amount of the solenoid 51 by the command current value calculated in this way. That is, the larger the absolute value of the deviation, the larger the absolute value of the command current value. The gain value is appropriately adjusted in advance so that the relationship between the deviation and the command current value to the solenoid 51 of the first control valve 50 allows the first control valve 50 to operate as desired.

When the target content is smaller than the actual content, the deviation becomes a negative value, and the controller 80 reduces the amount of power supplied to the solenoid 51 of the first control valve 50 by the command current value. As a result, the degree of opening of the first control valve 50 is reduced. When the degree of opening of the first control valve 50 decreases, the pressure loss caused by the first control valve 50 increases, so that it becomes difficult for the hydraulic fluid to be led from the pipeline portion 41 to the lead-out passage 13 . As a result, the back pressure generated in the pipeline portion 41 increases, and the air bubbles separated in the pipeline portion 41 are easily discharged through the vent port 46 (see FIG. 3). Therefore, when the degree of opening of the first control valve 50 decreases, the amount of air bubbles removed from the hydraulic fluid in the pipeline portion 41 increases, and the air bubble content of the hydraulic fluid guided to the lead-out passage 13 decreases. Therefore, the actual content is reduced, and the deviation from the target content is reduced.

When the target content is larger than the actual content, the deviation becomes a negative value, and the controller 80 increases the amount of power supplied to the solenoid 51 of the first control valve 50 by the command current value. As a result, the degree of opening of the first control valve 50 increases. When the degree of opening of the first control valve 50 increases, the pressure loss generated in the first control valve 50 decreases and the back pressure generated in the conduit section 41 decreases. It becomes difficult to be discharged through the vent port 46 . As a result, the air bubble content of the hydraulic oil led to the lead-out passage 13 increases. Therefore, the actual content increases and the deviation from the target content decreases.

By feedback-controlling the operation of the first control valve 50 at predetermined time intervals in this manner, the content of air bubbles in the hydraulic oil is adjusted so that the actual content matches the target content.

The target content is set such that the content of air bubbles in the hydraulic oil sucked by the hydraulic pump 30 is a value suitable for performance evaluation tests. In this embodiment, the measuring device 70 is provided in the outlet passage 13 instead of the suction passage 11 and measures the bubble content of the hydraulic oil discharged from the hydraulic pump 30 and returned to the tank 20 . Therefore, the target content is set to a value obtained by subtracting the amount of air bubbles contained in the tank 20 by the air bubble mixing device 60 from the air bubble content suitable for the performance evaluation test.

The amount of air bubbles contained in the hydraulic oil by the air bubble mixing device 60 can be obtained based on the rotation speed of the electric motor 62 . In this embodiment, since the electric motor 62 of the air bubble mixing device 60 rotates at a constant speed, the amount of air bubbles contained in the hydraulic oil by the air bubble mixing device 60 is substantially constant and can be easily grasped.

As described above, by controlling the operations of the bubble mixing device 60 and the bubble removing device 40 and adjusting the bubble content so that the actual content matches the target content, the amount of hydraulic oil sucked by the hydraulic pump 30 is reduced. The bubble content can be as desired. Therefore, it is possible to accurately evaluate the performance of the hydraulic pump 30 that is used under conditions where air bubbles are likely to be contained.

Here, in general, inside the hydraulic pump, air bubbles may be generated in the hydraulic oil due to cavitation or the like. Since the amount of air bubbles generated inside the hydraulic pump varies depending on the operating conditions of the hydraulic pump, etc., it is difficult to set the target air bubble amount in consideration of the air bubbles generated inside the hydraulic pump. In such a case, if a measuring device is provided in the discharge passage, the bubble content of the hydraulic oil containing bubbles generated inside the hydraulic pump will be measured as the actual content. The first control valve is feedback-controlled so that the actual content including air bubbles becomes the target content. That is, the amount of air bubbles actually contained in the hydraulic fluid sucked by the hydraulic pump is less than the desired air bubble content by the amount of air bubbles generated inside the hydraulic pump. Therefore, performance evaluation of the hydraulic pump cannot be performed under appropriate conditions, and the accuracy of performance evaluation may deteriorate.

In contrast, in the present embodiment, the measuring device 70 is provided not in the discharge passage 12 but in the lead-out passage 13 . The measuring device 70 measures the bubble content of the hydraulic oil that has passed through the bubble removing device 40 as the actual content, and the first control valve 50 is feedback-controlled based on this actual content. Therefore, even if bubbles are generated inside the hydraulic pump 30, the bubbles are removed by the bubble removing device 40 accordingly. The bubble content of the hydraulic oil led to is controlled to the target content. Therefore, according to the present embodiment, performance evaluation can be performed with high accuracy.

According to the above embodiment, the following effects are obtained.

In the bubble content adjustment system 100, the operation of the bubble mixing device 60 for adding bubbles to the hydraulic oil and the bubble removing device 40 for removing bubbles from the hydraulic oil are controlled. Therefore, in a system such as the performance evaluation system 1 of the hydraulic pump 30 that requires a certain amount of bubble content in the hydraulic oil, the bubble content in the hydraulic oil can be adjusted to a desired value.

In addition, in the bubble content adjustment system 100 , the bubble removal device 40 has a first control valve 50 provided in the outlet passage 13 and a second control valve 55 provided in the discharge passage 14 . As a result, both the flow rate of the hydraulic oil that passes through the lead-out passage 13 with bubbles removed and the flow rate of the hydraulic oil that passes through the discharge passage 14 containing the removed bubbles are controlled. The degree of freedom in adjusting the amount of air bubbles to be removed can be improved.

Further, the measuring device 70 measures the bubble content of the hydraulic oil that has passed through the bubble removing device 40 as the actual content, and the first control valve 50 is feedback-controlled based on this actual content. Therefore, even if bubbles are generated inside the hydraulic pump 30, the bubbles are removed by the bubble removing device 40 accordingly. The bubble content of the hydraulic oil led to is controlled to the target content. Therefore, according to the air bubble content adjustment system 100, the performance evaluation in the performance evaluation system 1 can be accurately performed.

Next, a modification of the above embodiment will be described.

First, a modification regarding the control of the operation of the bubble mixing device 60 and the bubble removing device 40 will be described.

In the above embodiment, the electric motor 62 of the bubble mixing device 60 is controlled to rotate at a constant speed and the second control valve 55 of the bubble removing device 40 is controlled to have a constant opening. By feedback-controlling the degree of opening of the first control valve 50 of 40, the air bubble content of the hydraulic oil is adjusted. That is, in the above-described embodiment, the air bubble mixing device 60 controls the amount of air bubbles contained in the hydraulic oil to be constant, and the air bubble removing device 40 controls the amount of air bubbles to be removed from the hydraulic oil to be changed to change the amount of air bubbles to be removed from the hydraulic oil. The bubble content inside is adjusted to the desired value.

On the other hand, in the bubble content adjustment system 100, the control of the operation of the first control valve 50 and the second control valve 55 of the bubble removal device 40 and the electric motor 62 of the bubble mixing device 60 is explained in the above embodiment. It is not limited to control. For example, in the air bubble content adjustment system 100, the amount of air bubbles that the air bubble mixing device 60 causes to be contained in the hydraulic oil may be changed, and the amount of air bubbles that the air bubble removal device 40 removes from the hydraulic oil may be controlled to be constant. Further, control may be performed so that both the amount of air bubbles contained in the hydraulic oil by the air bubble mixing device 60 and the amount of air bubbles removed from the hydraulic oil by the air bubble removing device 40 are changed.

In other words, any one of the rotation speed of the electric motor 62 of the bubble mixing device 60, the opening degree of the first control valve 50 of the bubble removing device 40, and the opening degree of the second control valve 55 of the bubble removing device 40 changes. may be controlled to vary and the others to be constant, any two may be controlled to vary and the others to be constant, or all three may be controlled to vary may be controlled to

For example, the rotation speed of the electric motor 62 of the bubble mixing device 60 and the opening of the first control valve 50 of the bubble removing device 40 are controlled to be constant, and the opening of the second control valve 55 of the bubble removing device 40 is measured by the measuring device 70. may be feedback-controlled based on the measured actual content. In this modification, the amount of bubbles contained in the hydraulic oil by the bubble mixing device 60 is substantially constant. Further, in this modification, when the actual content is larger than the target content, the second control valve 55 is controlled to increase the degree of opening. As the degree of opening of the second control valve 55 increases, the flow rate of hydraulic oil containing air bubbles discharged to the sub-tank 21 through the vent port 46 increases. As a result, the amount of air bubbles removed from the fluid pressure chamber 42 increases, so the amount of air bubbles contained in the hydraulic oil that flows back to the circulation passage 10 after passing through the first control valve 50, that is, the actual content, decreases. and the deviation between the actual content and the target content becomes small. On the contrary, when the actual content is smaller than the target content, the opening of the second control valve 55 is controlled to decrease. When the degree of opening of the second control valve 55 decreases, the flow rate of hydraulic oil containing air bubbles discharged to the sub-tank 21 through the vent port 46 decreases. As a result, the amount of air bubbles removed from the fluid pressure chamber 42 decreases and the amount of air bubbles remaining in the fluid pressure chamber 42 increases. deviation becomes smaller.

Further, for example, the opening degrees of the first control valve 50 and the second control valve 55 of the bubble removing device 40 are respectively controlled to be constant, and the rotation speed of the electric motor 62 of the bubble mixing device 60 is measured by the measuring device 70. Feedback control may be performed based on the amount. In this modification, the amount of bubbles removed from the hydraulic oil by the bubble removal device 40 is substantially constant. In this modification, when the actual content is greater than the target content, the electric motor 62 of the aeration device 60 is controlled to reduce its rotation speed. When the rotation speed of the electric motor 62 decreases, the amount of hydraulic fluid stirred in the tank 20 decreases, and the amount of air bubbles contained in the hydraulic fluid in the tank 20 decreases. Since the amount of air bubbles removed by the air bubble removing device 40 is substantially constant, the amount of air bubbles contained in the hydraulic oil in the tank 20 decreases, the actual content decreases, and the actual content and the target content become different. deviation becomes smaller. Conversely, when the actual content is smaller than the target content, the electric motor 62 is controlled to increase its rotation speed. As the rotation speed of the electric motor 62 increases, the amount of air bubbles contained in the hydraulic oil in the tank 20 increases. This increases the actual content and reduces the deviation between the actual content and the target content.

Also in each of the modifications described above, the bubble content of the hydraulic oil flowing through the circulation passage 10 can be controlled to a desired value.

In this specification, "to control the operation of the control valves of the bubble removing device and the bubble mixing device" means the operating states (opening degree or It includes not only controlling to change the rotational speed), but also controlling to keep any one or two operating states constant.

Next, another modified example will be described.

In the above-described embodiment, the hydraulic pump 30 functions as a pump that circulates hydraulic oil in the circulation passage 10 and is also an evaluation target for performance evaluation in the performance evaluation system 1 . On the other hand, as shown in FIG. 5, the evaluation test circuit system including the hydraulic pump 30 to be evaluated and the bubble content adjustment circuit system including the hydraulic pump 30 different from the evaluation target are provided. Each may be provided. In the modification shown in FIG. 5, in addition to the circulation passage 10 in the air bubble content adjustment system 100, there is a second circulation passage 15 for evaluation that circulates hydraulic oil between the tank 20 and the hydraulic pump P to be evaluated. be provided. The evaluation measuring device 2 is provided in the second circulation passage 15 and measures the pressure and flow rate of the hydraulic oil discharged from the hydraulic pump P. As shown in FIG. Even in such a modified example, the same effects as those of the above-described embodiment can be obtained. Further, the evaluation target of the performance evaluation is not limited to the pump, and may be other hydraulic equipment such as a hydraulic motor.

Further, in the above embodiment, the bubble mixing device 60 has gears 61a and 61b provided in the tank 20 and the electric motor 62 that drives the gears 61a and 61b. On the other hand, the air bubble mixing device 60 is not limited to the configuration of the above-described embodiment, and may be of any other configuration as long as the hydraulic oil flowing through the circulation passage 10 can contain air bubbles. For example, the bubble mixing device 60 may include an air compressor and a nozzle that causes the hydraulic oil in the circulation passage 10 to contain the air discharged from the air compressor. In this case, the controller 80 controls the operation of the drive source (electric motor, etc.) of the air compressor and the operation of the control valve that controls the flow rate of the air passing through the nozzle, and the air bubble mixing device 60 causes the hydraulic oil to contain The amount of air bubbles should be adjusted.

Further, in the above embodiment, the measuring device 70 measures the air bubble content of the hydraulic oil guided from the air bubble removing device 40 to the tank 20 . On the other hand, at which position in the circulation passage 10 the measurement device 70 measures the bubble content of the hydraulic oil can be configured arbitrarily. In addition, as described above, in order to suppress the influence of air bubbles generated in the hydraulic pump 30, the measuring device 70 is designed to measure the hydraulic oil discharged from the hydraulic pump 30 and guided to the air bubble removing device 40 (in other words, the discharge passage 12). The air bubble content of the hydraulic oil that passes through the bubble removing device 40 and is sucked into the hydraulic pump 30 (in other words, the hydraulic oil that passes through the recirculation passage, the tank 20, and the suction passage 11) rather than the hydraulic oil that passes through Measurement is desirable.

Further, in the above-described embodiment, the first control valve 50 and the second control valve 55 are provided in the lead-out passage 13 and the discharge passage 14 connected to the bubble removing device 40, respectively. On the other hand, at least one of the first control valve 50 and the second control valve 55 should be provided to control the operation of the bubble removing device 40 . Further, the first control valve 50 and the second control valve 55 are not limited to proportional solenoid valves, and may be other valves as long as the opening is controlled by the controller 80 .

Configurations, functions, and effects of embodiments of the present invention will be collectively described below.

The bubble content adjustment system 100 includes a tank 20 that stores hydraulic oil, a hydraulic pump 30 that sucks and discharges the hydraulic oil stored in the tank 20, and circulates the hydraulic oil between the tank 20 and the hydraulic pump 30. a circulation passage 10, a bubble removal device 40 provided in the circulation passage 10 for removing bubbles in the hydraulic oil, an air bubble mixing device 60 for adding bubbles to the hydraulic oil flowing through the circulation passage 10, and the hydraulic oil flowing through the circulation passage 10 and a controller 80 for adjusting the air bubble content in the hydraulic oil. It has a discharge passage 12 leading to the device 40, a lead-out passage 13 leading the hydraulic oil from which bubbles have been removed by the bubble removing device 40, and a discharge passage 14 discharging the bubbles removed by the bubble removing device 40. The removal device 40 has a control valve (first control valve 50, second control valve 55) that controls the flow rate of at least one of the hydraulic fluid passing through the lead-out passage 13 and the hydraulic fluid passing through the discharge passage 14, and the controller 80 controls the operation of the control valves (the first control valve 50 and the second control valve 55) of the bubble removing device 40 and the bubble mixing device 60 based on the measurement result of the measuring device 70. FIG.

In this configuration, by controlling the operation of the air bubble mixing device 60 that increases the air bubble content in the hydraulic oil and the air bubble removal device 40 that reduces the air bubble content in the hydraulic oil, the air bubble content in the hydraulic oil is reduced. You can increase or decrease the amount. Therefore, the air bubble content of the hydraulic oil can be adjusted.

Further, in the air bubble content adjustment system 100 , control valves (the first control valve 50 and the second control valve 55 ) are provided in each of the lead-out passage 13 and the discharge passage 14 .

In this configuration, since both the flow rate of the hydraulic oil that passes through the lead-out passage 13 with bubbles removed and the flow rate of the hydraulic oil that contains the removed bubbles and passes through the discharge passage 14 are controlled, the bubble removal device 40 The degree of freedom in adjusting the amount of air bubbles removed by is improved.

In addition, in the air bubble content adjustment system 100 , the measuring device 70 measures the air bubble content of hydraulic oil discharged from the hydraulic pump 30 and guided to the tank 20 through the air bubble removing device 40 .

In this configuration, the measurement device 70 measures the air bubble content of the hydraulic oil that passes through the air bubble removal device 40 and is sucked into the hydraulic pump 30, rather than the hydraulic oil that is discharged from the hydraulic pump 30 and led to the air bubble removal device 40. . Therefore, even if bubbles are generated inside the hydraulic pump 30, the bubbles are removed by the bubble removing device 40 accordingly. The foam content of the oil can be controlled to the desired value.

Although the embodiments of the present invention have been described above, the above embodiments merely show a part of application examples of the present invention, and the technical scope of the present invention is not limited to the specific configurations of the above embodiments. do not have.

Reference Signs List 10 Circulation passage 12 Discharge passage 13 Derivation passage 14 Discharge passage 20 Tank 30 Hydraulic pump (pump) 40 Bubble removing device 50 First control valve (control valve) 55 ... second control valve, 60 ... bubble mixing device, 70 ... measuring device, 80 ... controller, 100 ... bubble content adjustment system

Claims (3)

A bubble content adjustment system for adjusting the content of bubbles in a liquid, comprising:
a tank for storing liquid;
a pump that sucks and discharges the liquid stored in the tank;
a circulation passage for circulating liquid between the tank and the pump;
a bubble removing device provided in the circulation passage for removing bubbles in the liquid;
an air bubble mixing device that causes the liquid flowing through the circulation passage to contain air bubbles;
a measuring device for measuring the content of air bubbles in the liquid flowing through the circulation passage;
a controller for adjusting the content of air bubbles in the liquid;
The circulation passage is
a discharge passage for guiding the liquid discharged from the pump to the bubble removing device;
an outlet passage for guiding the liquid from which bubbles have been removed by the bubble removing device;
a discharge passage for discharging liquid containing bubbles removed by the bubble removing device;
The bubble removing device has a control valve that controls the flow rate of at least one of the liquid passing through the lead-out passage and the liquid passing through the discharge passage,
The air bubble content adjusting system, wherein the controller controls the operation of the control valve of the air bubble removing device and the air bubble mixing device based on the measurement result of the measuring device. 2. The air bubble content adjustment system according to claim 1, wherein the control valve is provided in each of the lead-out passage and the discharge passage. 3. The air bubble content adjustment system according to claim 1, wherein the measuring device measures the air bubble content of the liquid sucked into the pump after passing through the air bubble removing device.

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