Liquid recovery device

Abstract

To provide a liquid recovery device capable of recovering liquid discharged from a liquid discharge part and storing the liquid in a storage tank without using a liquid pump.SOLUTION: The first return passage part 21 extends so as to communicate a discharge port 113 of the spindle unit 11 with a lower part of the intermediate tank 22, and a predetermined part 211 adjacent to the discharge port 113 extends above the discharge port 113 to constitute a liquid passage through which the oil L flows. The intermediate tank 22 is provided above the storage tank 12 and serves as a Melmo for storing the oil L in an internal airtight space. The second return passage section 23 extends so as to communicate the lower part of the intermediate tank 22 with the lower part of the storage tank 12, and constitutes a liquid passage through which the oil L flows. The ejector 24 is connected to the upper portion of the intermediate tank 22 and reduces the internal pressure of the intermediate tank 22 by discharging gas from the inside of the intermediate tank 22 to the outside.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a liquid recovery device. [Background technology]

[0002] Patent Document 1 describes a machine tool equipped with a spindle unit. In this machine tool, an oil passage is formed inside the spindle unit. When the machine tool is in operation, oil, a cooling liquid, is supplied to the oil passage. After being used to cool the spindle unit, this oil is discharged from an outlet of the spindle unit. The discharged oil is then collected and stored in a storage tank. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-190150 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned machine tool, it is conceivable to provide a pump to pump the oil discharged from the spindle unit and send it to the storage tank. By providing a pump, the oil can be smoothly sent to the storage tank. However, in this case, a large amount of air may enter the pump, causing poor discharge, or cavitation, which may lead to increased vibration and noise.

[0005] This situation is not limited to liquid recovery devices that recover oil discharged from a spindle unit and store it in a storage tank, but is generally common to liquid recovery devices that recover liquid (oil or cooling water) discharged from some kind of equipment and store it in a storage tank. [Means for solving the problem]

[0006] A liquid recovery device that solves the above-mentioned problems is a liquid recovery device that recovers liquid discharged from a discharge port of a liquid discharge unit and stores it in a storage tank, and is equipped with a first return passage section, an intermediate tank, a second return passage section, and a pressure reduction section, wherein the first return passage section extends to communicate between the discharge port and a lower part of the intermediate tank and extends at least partially above the discharge port to form a liquid passage through which the liquid flows, the intermediate tank is provided above the storage tank and stores the liquid in an airtight space therein, the second return passage section extends to communicate between a lower part of the intermediate tank and a lower part of the storage tank to form a liquid passage through which the liquid flows, and the pressure reduction section is connected to an upper part of the intermediate tank and reduces the internal pressure of the intermediate tank by discharging gas from inside the intermediate tank to the outside.

[0007] According to the above configuration, the pressure reduction unit can reduce the internal pressure of the intermediate tank to a pressure lower than atmospheric pressure (hereinafter referred to as negative pressure). This negative pressure can then be used as a suction force to suck the liquid discharged from the discharge port of the liquid discharge unit toward the intermediate tank via the first return passage, allowing the liquid to be sent to the intermediate tank. Furthermore, the liquid in the intermediate tank can be sent to a storage tank located below the intermediate tank via the second return passage by utilizing gravity. Thus, according to the above configuration, the liquid discharged from the liquid discharge unit can be collected and stored in the storage tank by utilizing the negative pressure generated by the pressure reduction unit without using a liquid pump. [Effects of the Invention]

[0008] According to the present invention, the liquid discharged from the liquid discharge portion can be collected and stored in the storage tank without using a liquid pump. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a schematic diagram of a liquid recovery device according to one embodiment. [Figure 2] FIG. 2 is an explanatory diagram illustrating the operation of the liquid recovery device of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the liquid recovery device will be described below. 1 and 2, a liquid recovery device 20 according to this embodiment is applied to a machine tool 10. The machine tool 10 includes a spindle unit 11. The spindle unit 11 has a spindle (not shown) that is a rotating shaft that rotates at high speed. A rotating tool such as a grinding wheel is attached to the spindle.

[0011] A hydrostatic bearing is used in the spindle unit 11. An oil passage 111 is provided inside the spindle unit 11. The oil passage 111 constitutes a part of the hydrostatic bearing. Oil L is supplied to the oil passage 111 when the machine tool 10 is in operation.

[0012] The machine tool 10 includes a storage tank 12, a supply passage section 13, and a pump 14. Oil L is stored in the storage tank 12. The storage tank 12 is open to the atmosphere. Therefore, the internal pressure of the storage tank 12 is approximately equal to atmospheric pressure. The supply passage section 13 constitutes a liquid passage through which the oil L flows, and extends so as to communicate between the storage tank 12 and the oil passage section 111. The pump 14 is provided midway along the supply passage section 13, and serves to pump the oil L in the storage tank 12 toward the spindle unit 11.

[0013] In this embodiment, the oil L pumped by the pump 14 flows into the oil passage portion 111 through the inlet 112 of the spindle unit 11. After passing through the oil passage portion 111, the oil L is discharged to the outside of the spindle unit 11 through the outlet 113 of the spindle unit 11. In this embodiment, the oil L corresponds to the liquid, and the spindle unit 11 corresponds to the liquid discharge portion.

[0014] The liquid recovery device 20 of this embodiment is for recovering the oil L discharged from the discharge port 113 of the spindle unit 11 and storing it in the storage tank 12. Liquid recovery device 20 includes a first return passage section 21, an intermediate tank 22, and a second return passage section 23. In liquid recovery device 20, outlet 113 of spindle unit 11 is connected to storage tank 12 via first return passage section 21, intermediate tank 22, and second return passage section 23. In liquid recovery device 20, first return passage section 21, intermediate tank 22, and second return passage section 23 are arranged in this order from the spindle unit 11 side.

[0015] <First return passage> The first return passage 21 constitutes a liquid passage through which the oil L flows. The first return passage 21 extends to communicate between the discharge port 113 of the spindle unit 11 and a lower portion of the intermediate tank 22 (more specifically, a portion below the liquid level of the oil L in the intermediate tank 22). For convenience of arrangement, a portion of the first return passage 21 (more specifically, a predetermined portion 211 adjacent to the discharge port 113) extends above the discharge port 113. In this embodiment, the discharge port 113 of the spindle unit 11 is located above the liquid level of the oil L in the storage tank 12, specifically above the storage tank 12.

[0016] <Intermediate tank> An airtight space is partitioned and formed inside the intermediate tank 22. The intermediate tank 22 stores oil L in the airtight space inside the intermediate tank 22. The intermediate tank 22 is provided above the storage tank 12.

[0017] <Second return passage> The second return passage 23 constitutes a liquid passage through which the oil L flows. The second return passage 23 extends so as to communicate between the intermediate tank 22 and the storage tank 12. Specifically, the end of the second return passage 23 on the intermediate tank 22 side is connected to the lower part of the intermediate tank 22, more specifically, to a part below the liquid level of the oil L in the intermediate tank 22. The second return passage 23 extends downward from the lower part of the intermediate tank 22. The end of the second return passage 23 on the storage tank 12 side is connected to the lower part of the storage tank 12, more specifically, to a part below the liquid level of the oil L in the storage tank 12.

[0018] <Ejector> The liquid recovery device 20 includes an ejector 24. In this embodiment, the ejector 24 is used to discharge gas from the inside of the intermediate tank 22 to the outside, thereby reducing the internal pressure of the intermediate tank 22. In this embodiment, the ejector 24 corresponds to a pressure reduction unit.

[0019] The ejector 24 is provided as follows: A vacuum port 241 of the ejector 24 is connected to the upper part of the intermediate tank 22, more specifically, to a portion above the liquid level of the oil L in the intermediate tank 22. A supply port 242 of the ejector 24 is connected to the compressor 15. An exhaust port 243 of the ejector 24 is connected via an exhaust passage 244 to the upper part of the storage tank 12, more specifically, to a portion above the liquid level of the oil L in the storage tank 12.

[0020] In this embodiment, when the machine tool 10 is in operation, compressed air is supplied from the compressor 15 to the ejector 24. When the compressed air entering through the supply port 242 passes through the interior of the ejector 24, the ejector 24 generates a space with a pressure lower than atmospheric pressure (hereinafter referred to as negative pressure). The ejector 24 uses this negative pressure as a suction force to suck in gas from the intermediate tank 22 through the vacuum port 241. The ejector 24 discharges the sucked gas together with the air to the outside of the ejector 24, specifically to the storage tank 12, through the exhaust port 243 and the exhaust passage 244.

[0021] <Operation of this embodiment> The operation of this embodiment will be described. 2, when the machine tool 10 is in operation, oil L is supplied to the oil passage portion 111 of the spindle unit 11. After passing through the oil passage portion 111, the oil L is discharged from the discharge port 113 of the spindle unit 11 to the first return passage portion 21.

[0022] Furthermore, as shown by arrow B1 in Fig. 2, when machine tool 10 is in operation, compressed air is supplied from compressor 15 to ejector 24. Therefore, as shown by arrow B2 in Fig. 2, part of the gas in intermediate tank 22 is sucked by ejector 24 and discharged to the outside of intermediate tank 22. This reduces the internal pressure of intermediate tank 22 to a negative pressure. Then, as shown by arrow B3 in Fig. 2, the gas sucked by ejector 24 is discharged to storage tank 12 via exhaust port 243 and exhaust passage 244.

[0023] Here, the oil L supplied to the spindle unit 11 is pressure-fed by the pump 14. Therefore, the pressure of the oil L discharged from the outlet 113 of the spindle unit 11 to the first return passage portion 21 is higher than atmospheric pressure (hereinafter referred to as positive pressure). In contrast, the internal pressure of the intermediate tank 22 is negative. Therefore, the internal pressure (negative pressure) of the intermediate tank 22 acts as a suction force that draws the positive-pressure oil L discharged from the spindle unit 11 to the first return passage portion 21 toward the intermediate tank 22. In this embodiment, this suction force causes the oil L discharged from the spindle unit 11 to be sucked into the intermediate tank 22 via the first return passage portion 21, as shown by arrows A2 and A3 in FIG. 2. The sucked oil L then flows into the airtight space inside the intermediate tank 22 and accumulates there.

[0024] In the present embodiment, a predetermined portion 211 of the first return passage portion 21 adjacent to the discharge port 113 extends above the discharge port 113. Therefore, the oil L passing through the first return passage portion 21 is temporarily lifted upward in the predetermined portion 211 before reaching the intermediate tank 22. In the present embodiment, the oil L in the first return passage portion 21 is sucked toward the intermediate tank 22 due to the negative pressure generated in the intermediate tank 22. Then, due to this suction force, the oil L in the first return passage portion 21 is lifted by the predetermined portion 211 as shown by arrow A2 in FIG. 2 and passes through the predetermined portion 211, and flows toward the intermediate tank 22 as shown by arrow A3 in FIG. 2.

[0025] Furthermore, in this embodiment, the storage tank 12 is disposed below the intermediate tank 22. Therefore, as shown by an arrow A4 in FIG. 2, the oil L in the intermediate tank 22 flows out into the storage tank 12 via the second return passage portion 23 due to gravity.

[0026] In this embodiment, the internal pressure of the storage tank 12 is approximately atmospheric pressure, while the internal pressure of the intermediate tank 22 is negative. This pressure difference generates a force that pulls the oil L in the second return passage 23 toward the intermediate tank 22, specifically, a force that pulls up the liquid level of the oil L in the intermediate tank 22. In this embodiment, the oil L flows through the second return passage 23 toward the storage tank 12 against this pulling force. Specifically, the vertical positional relationship between the storage tank 12 and the intermediate tank 22 and the shapes of the storage tank 12, the intermediate tank 22, and the second return passage 23 are determined so that an appropriate amount of oil L flows through the second return passage 23 against the pulling force.

[0027] <Effects of this embodiment> The effects of this embodiment will be described. (1) The liquid recovery device 20 includes a first return passage 21, an intermediate tank 22, a second return passage 23, and an ejector 24. The first return passage 21 extends to communicate between the discharge port 113 of the spindle unit 11 and the lower part of the intermediate tank 22, and a predetermined portion 211 adjacent to the discharge port 113 extends above the discharge port 113, thereby forming a liquid passage through which the oil L flows. The intermediate tank 22 is provided above the storage tank 12 and stores the oil L in an airtight space therein. The second return passage 23 extends to communicate between the lower part of the intermediate tank 22 and the lower part of the storage tank 12, thereby forming a liquid passage through which the oil L flows. The ejector 24 is connected to the upper part of the intermediate tank 22 and discharges gas from the inside of the intermediate tank 22 to the outside, thereby reducing the internal pressure of the intermediate tank 22.

[0028] If a liquid pump were provided to pump the oil L discharged from the spindle unit 11 to the storage tank 12, air entrapment and cavitation could occur, resulting in increased vibration and noise. Furthermore, if no device were provided to pump the oil L discharged from the spindle unit 11 to the storage tank 12, the oil L would likely accumulate in the oil passage 111. Therefore, in some cases, the internal pressure of the oil passage 111 could increase, causing the oil L to leak to the outside of the spindle unit 11 through a seal (not shown) of the spindle unit 11. Even if such a device were provided, if the amount of oil L pumped (e.g., the pump pumping amount) becomes too large, the internal pressure of the oil passage 111 could decrease, resulting in air being sucked into the oil passage 111 through the seal.

[0029] The above configuration achieves the effects of the above-described embodiment, and therefore, by utilizing the negative pressure generated by the ejector 24 without using a liquid pump, the oil L discharged from the spindle unit 11 can be collected and stored in the storage tank 12. The above configuration makes it possible to appropriately collect the oil L discharged from the spindle unit 11 and store it in the storage tank 12 while suppressing leakage of the oil L from the oil passage 111 and intrusion of air into the oil passage 111. Moreover, the above configuration does not use a liquid pump, and therefore it is possible to improve the function of collecting the oil L and suppress deterioration of vibration and noise compared to when a liquid pump is used.

[0030] (2) The pressure reduction unit is the ejector 24 having a vacuum port 241 connected to the intermediate tank 22. According to this configuration, the ejector 24 can realize a structure for reducing the internal pressure of the intermediate tank 22.

[0031] (3) The exhaust port 243 of the ejector 24 is connected to the storage tank 12. The gas sucked out from the inside of the intermediate tank 22 by the ejector 24 may contain mist-like oil L. With the above configuration, such gas can be temporarily returned to the inside of the liquid recovery device 20, specifically to the storage tank 12, without being directly released to the outside of the liquid recovery device 20. This makes it possible to prevent the oil L from leaking outside the liquid recovery device 20.

[0032] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0033] The exhaust port 243 of the ejector 24 may be open to the atmosphere instead of being connected to the storage tank 12. A gas pump may be provided instead of the ejector 24. In this case, the gas pump may be provided so as to discharge gas from the inside of the intermediate tank 22 to the outside. With this configuration, the internal pressure of the intermediate tank 22 can also be reduced by operating the gas pump. In the above configuration, the gas pump corresponds to the pressure reduction unit.

[0034] The extension of the first return passage section 21 can be changed as desired as long as at least a portion of it extends above the discharge port 113. For example, the first return passage section 21 may be extended to have a plurality of portions that extend above the discharge port 113. Alternatively, the first return passage section 21 may be extended so that the entire first return passage section 21 extends above the discharge port 113.

[0035] The discharge port 113 of the spindle unit 11 may be provided so as to be at approximately the same height as the liquid level of the oil L in the storage tank 12. Alternatively, the discharge port 113 of the spindle unit 11 may be provided at a position slightly higher than the liquid level of the oil L in the storage tank 12.

[0036] The liquid recovery device according to the above embodiment is not limited to application to machine tool 10 having spindle unit 11, but can be applied to any device that has some kind of device for discharging liquid. In this case, the device to which the device is applied is not limited to machine tools, and may be devices other than machine tools. Furthermore, the liquid to be recovered is not limited to oil L, but may be lubricating oil, cooling oil, or cooling water. An example of such a device is a bearing device having a cooling passage through which cooling oil is supplied and discharged. [Explanation of symbols]

[0037] 10…Machine tools 11...Spindle unit 111...Oil passage 112...Inlet 113...Exhaust port 12...Storage tank 13...Supply passage section 14...Pump 15...Compressor 20...Liquid recovery device 21...First return passage 211...Predetermined part 22...Intermediate tank 23...Second return passage 24...Ejector 241...Vacuum port 242…Supply port 243...Exhaust port 244...Exhaust passage

Claims

1. A liquid recovery device that recovers liquid discharged from a discharge port of a liquid discharge part and stores it in a storage tank, a first return passage portion, an intermediate tank, a second return passage portion, and a pressure reduction portion; the first return passage portion extends so as to communicate between the discharge port and a lower portion of the intermediate tank, and at least a portion of the first return passage portion extends above the discharge port to form a liquid passage through which the liquid flows, the intermediate tank is provided above the storage tank and stores the liquid in an internal airtight space, the second return passage portion extends so as to communicate between a lower portion of the intermediate tank and a lower portion of the storage tank, and constitutes a liquid passage through which the liquid flows; the pressure reduction unit is connected to an upper portion of the intermediate tank and reduces the internal pressure of the intermediate tank by discharging gas from the inside of the intermediate tank to the outside. Liquid recovery device.

2. the pressure reduction unit is an ejector having a vacuum port connected to the intermediate tank; The liquid recovery device according to claim 1 .

3. The exhaust port of the ejector is connected to the storage tank. The liquid recovery device according to claim 2 .

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