JPS61159129A - Detecting device for oil leak of shaft seal - Google Patents

Abstract

PURPOSE:To detect a leak of oil automatically without malfunction by providing a shaft seal which prevents working oil from flowing out, an oil pocket, an oil reservoir, and a detecting means. CONSTITUTION:A hydraulic pump 1 sucks the working oil and discharges high- pressure oil according to the rotation of its main driving shaft 3. An oil leak in the process of the suction, compression, and discharge is prevented by the shaft seal 5, but when its sealing performance deteriorates in long-time use, the working oil flows out to the oil pocket 11. The working oil is reserved in the reservoir 13 through an oil conduit 12 and the float 16 in the oil reservoir 13 rises according to the amount of the reserved oil. A magnetic plate 17 is stuck on the top surface of the float 16 nearby a proximity switch 14, so a current supplies through part of a cable 19 varies. The electric signal based upon the current is outputted through another cable and sent to a control unit, etc. Consequently, the oil leak is detected automatically.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an oil leak detection device for a shaft seal.
The present invention relates to a device for detecting hydraulic oil flowing out of a shaft seal through a main drive shaft. This is used in the field of hydraulic equipment, such as hydraulic pumps, in which hydraulic fluid under pressure flows.

[Prior art]

In hydraulic pumps driven by electric motors or engines, the most common problem, other than failures inside the main body such as bearing damage or damage around the piston, is oil leakage from the shaft seal. Conventionally, oil leakage from the casing was first detected visually, so the discovery of the problem was delayed, making repairs time-consuming, reducing the operating efficiency of vehicles equipped with it, and causing damage to the hydraulic pump itself or There is a problem of contamination of surrounding car bodies and roads.

By the way, hydraulic power excavators equipped with hydraulic pumps are becoming larger year by year, and various devices and parts are being used. There are growing demands for longer lifespans, improved reliability, no need for maintenance, prevention of malfunctions, etc. of various operating devices. For this reason, it is desired to reduce the occurrence rate of failures in each device and to automate detection to enable early detection.

Although improvements in technology have extended the lifespan of the hydraulic pumps described above, their durability is limited. Shaft seals such as oil seals are no exception, and from the standpoint of maintenance, it is necessary to automatically detect oil leaks. Furthermore, the detection device itself is required to have a longer lifespan, improved reliability, requires no maintenance, and prevents malfunctions than other devices.
It must be able to resist problems even when mounted on something that moves in a variety of ways and is subject to strong vibrations, such as a hydraulic power shovel.

[Purpose of the invention]

The present invention was made in view of the above-mentioned problems, and its purpose is to automatically detect oil leakage from the shaft seal of a hydraulic pump, etc., and to ensure that the components necessary for the detection have a long life, high reliability, and It is an object of the present invention to provide an oil leakage detection device for a shaft seal that does not require maintenance and is not affected by tilting or vibration of a vehicle body and does not malfunction.

[Structure of the invention]

The features of the shaft seal oil leak detection device of the present invention will be explained with reference to FIGS. 1(a) and 1(b).
A shaft seal 5 that prevents the hydraulic oil in the casing from flowing out through the main drive shaft 3 and a dust seal member 10 provided on the outermost side of the main drive shaft 3 that prevents dust from entering. In between, an oil pocket 11 is formed, and an oil reservoir 13 is installed in which leaked oil from the shaft seal 5 drips to the lower part of the oil pocket 11 and remains therein. The detection means 14 for detection is arranged so as to face the oil sump 13.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below using examples of devices to which the present invention is applied.

Figure 2 shows the appearance of a typical hydraulic pump 1, with the pump body 2
is provided with a main drive shaft 3, a bearing 4, a shaft seal 5, etc. A coupling 7 is attached to the pump body 2 at the tip of a main drive shaft 3 that passes through a flange 6 that closes the body, and power is supplied from a drive source such as an electric motor or an engine (not shown). ing. A hydraulic oil inlet or discharge port 8 is opened in the main body casing, and the hydraulic oil pumped up from the oil tank is pressurized and supplied to each predetermined hydraulic actuator. A tilting motion is to be performed. Incidentally, the main body 2 of the hydraulic pump is mounted at a predetermined position on a hydraulic power shovel or the like using a support 9 as shown by the chain line.

FIG. 1(a) is an enlarged view of the part that supports the main drive shaft 3.
A shaft seal 5 that prevents hydraulic oil in the main body casing from flowing out through the main drive shaft 3 is provided adjacent to the bearing 4 on its outer side. This shaft seal 5 is a commonly used and well-known oil seal, and is a ring-shaped coil that is fitted onto the outside of the main drive shaft 3 and inserted into the annular space to reduce the diameter of the inner lip 5a. The spring 5M ensures oil tightness around the shaft. On the other hand, a dust seal member 10 is provided on the outermost side of the main drive shaft 3 to prevent dust from entering the casing.

An oil pocket 11 is formed in the casing between this dust seal member and the above-mentioned shaft seal 5. This oil pocket is an oil guide path 12 formed in the casing.
At the lower tip of the oil guide path, there is an oil reservoir 13 in which leaked oil from the shaft seal 5 drips and accumulates, as shown in Figure 1 (b).
), it is installed inside the casing, etc. Note that the oil pocket 11 only needs to guide the leaked oil that has leaked beyond the shaft seal 5 toward the dust seal member 10 to the oil guide path 12 without leaking it outside the casing, so its shape and dimensions are determined according to the inside of the casing. Any arrangement can be made depending on the space available and the arrangement of the shaft seal 5 and dust seal member 10. Oil pocket 1 of main drive shaft 3
It is convenient if a flange-shaped oil cutter or the like is attached to one part, since leakage to the dust seal member 10 side can be almost eliminated.

A proximity switch 14, which is a means for detecting the presence or absence of leaked oil stagnant therein or the amount of stagnant oil, faces the oil sump 13. This is supported, for example, by a holder 15 that fits into a hole drilled in the casing as shown, and the holder is attached by threaded engagement. The sensing part of the proximity switch 14 protrudes from the tip of the holder 15, and an oil reservoir 1 is located below it.
A float 16 is floating on the oil surface of 3. If the proximity switch 14 is of a magnetic type, eddy current type, capacitance type, etc., magnetic plates 17 are attached above and below the float 16. Note that the magnetic plate may be used only on the top surface, but the float 1
It is recommended that oil reservoirs 13 be provided on both sides in case the vehicle falls over.Although the oil reservoir 13 is relatively shallow in the illustration, it is recommended to make it deep in consideration of the rocking of the vehicle body. Preferably, a plug 18 is attached to the bottom of the oil reservoir 13,
By removing it, the accumulated leaked oil can be disposed of if necessary.

According to the embodiment having such a configuration, the presence or absence of oil leaking from the shaft seal 5 and the amount thereof are detected as described below.

The hydraulic pump 1 sucks hydraulic oil, and discharges high-pressure oil from a discharge port 8 as the main drive shaft 3 rotates. Its inhalation, compression,
During the discharge process, oil leakage always occurs, albeit a very small amount. The leaked oil once flows into the casing and is returned to the drain line or suction line. At this time, the line pressure is higher than atmospheric pressure, and oil leakage from the main drive shaft 3 is prevented by the shaft seal 5. However, when the sealing performance deteriorates due to long-term use, the hydraulic oil flows through the bearing 4 and flows out from the lip 5a of the shaft seal 5 into the oil pocket 11. The leaked oil passes through the oil guide path 12 and is stored in the oil reservoir 13. Since a float 16 is disposed in the oil reservoir, it rises in accordance with the amount of retained oil. Since the magnetic plate 17 is attached to the upper surface of the float that approaches the sensing part of the proximity switch 14, the current supplied through a part of the cable 19 changes. The resulting electrical signal is output via another cable and transmitted to a control unit (not shown) or the like. Since the strength of the signal varies depending on the degree of proximity of the magnetic plate 17, it is also possible to detect the amount of retained oil. It should be noted that even if the proximity switch 14 is detected by the other electrical method described above, qualitative on/off detection or quantitative detection of the oil amount is performed in the same manner.

This proximity switch has a simple structure and no moving parts.
Since the float that changes depending on the amount of oil may have a simple shape, its detection life is extremely long. What's more, it requires almost no maintenance, and there are almost no malfunctions caused by tilting, shaking, or vibration of the vehicle body, dramatically improving its reliability.

FIG. 3 shows a different embodiment, in which an ultrasonic sensor 20 is employed as the detection means. This sensor takes advantage of the fact that the transmitted ultrasonic signal has poor permeability in the air compared to oil, and the attenuation in the air is large, weakening the reflected waves from the facing wall and causing the stagnation. The amount of oil can be detected. Therefore, as the amount of oil on the sensor surface increases, the amount of reflected waves increases.

As described above, in any of the examples, the presence or absence and amount of oil leaking from the shaft seal can be automatically and remotely detected by the detection means. Normally, the main drive shaft of a hydraulic pump mounted on a hydraulic excavator is narrow and often dirty (
Although visual inspection and other inspections are difficult, this is no longer necessary, and the amount of maintenance work for vehicles equipped with it can be greatly reduced.

〔Effect of the invention〕

As can be seen from the detailed description of the embodiments above, the present invention forms an oil pocket between the shaft seal and the dust seal member, causes leaked oil from the shaft seal to stay in an oil reservoir communicating with the oil pocket, and Since this can be detected by the detection means, oil leakage from the hydraulic pump can be known in advance, and various troubles caused by leakage can be avoided. Furthermore, the structure of the device itself is simple, maintenance and inspection work is unnecessary or reduced, and maintenance of the entire vehicle such as a hydraulic power shovel becomes easy. In addition, the detection device is almost unaffected by tilting, shaking, and four vibrations of the vehicle body, thus preventing malfunctions and generation of false signals.

[Brief explanation of drawings]

FIG. 1(a) is a sectional view of the main parts of a hydraulic pump equipped with the shaft seal oil leakage detection device of the present invention, and FIG. 1(b) is the same figure (
FIG. 2 is an example of an overall external view of a hydraulic pump, and FIG. 3 is a sectional view of a different embodiment. 3-Main drive shaft, 5-Axis seal, 10-Dust seal member, 11-Oil pocket, 13-Oil reservoir, 14.20
- detection means (proximity switch, ultrasonic sensor); Agent Patent attorney Katsutoshi Yoshiso (one idiot) Figure 1 (a) ■ Figure 9J1 (b)

Claims (1)

[Claims] (1) Between the shaft seal that prevents the hydraulic oil in the casing from flowing out through the main drive shaft and the dust seal member provided on the outermost side of the main drive shaft that prevents dust from entering. An oil pocket is formed in the shaft seal, and an oil reservoir is installed in which leaked oil from the shaft seal drips and stays at the bottom of the oil pocket, and a detection method is installed to detect the presence or absence of leaked oil accumulated in the oil reservoir or the amount of accumulated oil. An oil leak detection device for a shaft seal, characterized in that the means is arranged so as to face an oil reservoir.