JPH03289530A - Apparatus for feeding contaminant mixed oil in hydraulic circuit - Google Patents

Abstract

PURPOSE:To supply oil having the intended contamination concentration into a sample without contaminating a tank and a pump by controlling the opening degree of a pilot operating valve, mixing detergent oil and contaminated oil, and supplying the mixture into the sample. CONSTITUTION:When a flow-rate control valve 4 is opened and a control valve 7 is closed, clean oil flows into a sample 5 from a hydraulic pump 2. The oil returns into an oil tank 1 through a filter 9. When the flow rates in the valves 4 and 7 are controlled, detergent oil and contaminant mixed oil from a contaminant tank 8 join, and both oils are mixed. The mixture flows into the sample 5. Therefore, the contaminant mixed oil having the intended concentration can be supplied into the sample 5 by controlling the opening degrees of the valves 4 and 7. The oil in the oil tank 1 and the pump 2 can be kept clean by passing the returned oil from the sample 5 through the filter 9. In this way, the mixed oil having the intended concentration can be supplied into the sample without contaminating the oil pump.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a hydraulic circuit contaminant mixed oil supply device,
In particular, the present invention relates to an improvement in a hydraulic circuit contaminant mixed oil supply device used in tests to confirm the limit of contamination resistance of hydraulic equipment used in construction machinery and the like.

(Prior Art) Conventionally, contaminants are mixed into hydraulic circuits used for testing the limits of contamination resistance of hydraulic equipment used in construction machinery, etc., and these contaminants include metals normally generated in hydraulic circuits. Wear particles (several microns to several millimeters) and oil deterioration products can be used. As shown in Fig. 2, this hydraulic circuit includes a hydraulic pump 2 that sucks up oil from a tank I that has been mixed with contaminants in advance, sends it to the actuator 3 of the sample, and returns it from the actuator of the sample. Contamination limits are tested by circulating oil into the tank and operating the actuator. Further, the test conditions such as actuator speed and load pressure at this time are such that the pressure is controlled by the pressure regulating valve 4 and the speed is also controlled.

(Problems to be Solved by the Invention) However, in the conventional hydraulic circuit described above, (1) the hydraulic pump itself also has problems in order to inject pollutants into the tank;
Due to the influence of pollutants, the lifespan may be shortened or breakdowns may occur.

(2) The concentration of pollutants cannot be reduced below the current level while the pump is operating. Furthermore, if a contaminant is added to the tank, the concentration will increase, but the concentration will be discontinuous, making it difficult to change the contaminant during the test.

(3) It is difficult to adjust the actuator speed and load pressure using the ml pressure valve. Furthermore, if a variable pump, flow rate control valve, etc. are used to control the actuator speed and load pressure, failures will occur even more due to the effect of (1).

There are other problems.

The present invention focuses on the above-mentioned problem, and relates to a hydraulic circuit contaminant mixed oil supply device, and particularly relates to an improvement of a hydraulic circuit contaminant mixed oil supply device used for contamination resistance limit confirmation tests and the like.

(Means for Solving the Problems) In order to achieve the above object, the present invention relates to a hydraulic circuit contaminant mixed oil supply device for testing the durability of a test sample, which comprises a hydraulic pump, an oil tank, and the like. , a flow control valve provided in a flow path between the pump and the sample, and a flow control valve provided between a flow path branched from the upstream of the flow control valve and a flow path downstream of the flow control valve. It consists of a pollutant tank and a pilot operated valve that controls the flow rate of the flow control valve.

(Function) According to the above configuration, if the flow rate control valve between the hydraulic pump and the specimen allows the flow to flow, and the flow rate control valve in front of the contaminant tank does not allow the flow to flow, the oil tank in the specimen Cleaner oil flows. If the flow rate is controlled by the pilot operated valve of the flow control valve, the oil from the hydraulic pump and the oil with the contaminant concentration from the contaminant tank are mixed according to the flow rate of each pilot operated valve, and the sample is mixed. is supplied to Therefore, by controlling the opening degree of the pilot operated valve, oil having a contaminant concentration as required can be supplied to the sample. In addition, by passing the oil returned from the sample through a filter, the oil in the oil tank can be maintained clean, and the oil flowing to the hydraulic pump will be clean, thereby preventing a reduction in the life of the hydraulic pump and failure. I can do it.

(Example) Hereinafter, an example of a hydraulic circuit contaminant mixed oil supply device according to the present invention will be described in detail with reference to the drawings. FIG. 1 is an overall configuration diagram of one embodiment of the present invention. The oil tank 1 and the hydraulic pump 2 are connected by a conduit 3, and the hydraulic pump 2 is connected to a specimen 5 by a flow conduit 6 via a flow control valve 4. The flow rate control valve 4 is provided with a pilot operated valve 4a that controls the flow rate. A flow control valve 7 is provided in a flow path 6a branched from the flow path 6 between the hydraulic pump 2 and the sample 5.
and a contaminant tank 8 are connected, and a flow path 6b from the contaminant tank 8 is returned to the flow path 6 between the flow rate control valve 4 and the specimen 5. The flow rate control valve 7 is also provided with a pilot operation valve 7a that similarly controls the flow rate. Returned oil from the sample 5 and the like is returned to the oil tank 1 via a filter 9. In the pollutant tank 8, a free piston 13 separates clean oil 0 and oil 11 having a pollutant concentration.

In the above configuration, the operation will be explained next. When the flow control valve 4 is open and the flow control valve 7 is closed, the entire amount of oil from the hydraulic pump 2 flows through the flow path 6 to the specimen 5, and the oil returning from the specimen 5 is passes through the filter 9 and returns to the oil tank l. Since the oil tank 1 contains clean oil, the oil flow at this time is clean oil. Next, the pilot operating valve 4a of the flow control valve 4 is operated to throttle the flow a little, and the pilot operating valve 7a of the flow rate control valve 7 is operated to open the pilot operating valve 7a slightly to allow the flow to flow, and some of the oil from the hydraulic pump 2 becomes contaminated. It flows into the left side of the free piston 13 of the material tank 8, pushes the free piston 13 to the right side, and pushes out a part of the large amount of highly concentrated contaminant mixed oil that was previously filled on the right side. Clean oil coming from channel 6 and channel 6
The highly concentrated contaminant mixed oil from b is joined and mixed in front of the sample 5 to produce a contaminant mixed oil with a constant concentration. When the flow control valve 4 is completely closed and the flow control valve 7 is opened, the entire amount of oil from the hydraulic pump 2 enters the contaminant tank 8, and only the highly concentrated contaminant mixed oil flows into the sample 5.

By setting the pilot operating valve 4a of the flow rate control valve 4 and the pilot operating valve 7a of the flow rate control valve 7 to appropriate opening degrees, it is possible to easily apply the contaminant mixed oil of the desired concentration to the sample 5 even when the hydraulic pump 2 is operating. I can send it.

An example of the structure of the flow control valve 4.7 will be explained with reference to FIG. Flow control valve main body 41 (hereinafter referred to as main body 41).

) is provided with a port 42 from the hydraulic pump 2, a port 43 for passing a flow rate to the next sample, etc., and a port 44 to the pilot operating valve 4a or 7a. Also,
A valve 46 having a slit 45 cut therein is tightly inserted into the main body 41 . A spring 47 and a bottle 48 are inserted inside the valve 46, and the spring 47 presses the valve 46 to the left in the drawing. The bottle 48 has one end in contact with a spring 47 and the other end in contact with a cover 49, and is pressed toward the cover 49 by the spring 47. The cover 49 is fixed to the main body 41 with bolts 50. The pilot operated valve 4a or 7a is connected to port 4.
Piping 51 from 4 and port 4 through which the flow rate flows to the sample, etc.
3 and the piping 52 to 3.

In the above configuration, the pressure of the port 42 is Pa, and the pressure of the valve 4 is Pa.
The cross-sectional area of 6 is Ac, the pressure of the port 43 is Pa, the cross-sectional area is Aa, the cross-sectional area of the small diameter part 48a of the bottle 48 is Ab, the pressure between the valve 46 and the large diameter part 48b of the bottle 48 is Pb, the main body 41 and the valve 46 is So, and the restriction area between the slit 45 of the valve 46 and the small diameter portion 48a of the bottle 48 is Sa.

Let the throttle area of the pilot operated valve be sb, the flow rate from the port 43 be Q a s, and the flow rate of the pilot operated valve be Qb1, and the force f1 of the spring 47. Look at the balance of forces in valve 46. The force Fr applied to the valve 46 in the illustrated right direction is Fr=Pa−Aa×Po (Ac−Aa) (I)
The force F1 to the left is F1=Pb (Ac-Ab)+Po-Ab+f...(
2) From left and right balance, Fr=Fl (1), (2)
is Pa-Aa+Po (Ac-Aa) = Pb (AC-Ab) + Po - Ab + f (3), and if the force f of the spring 47 is small, then f″=,0. , (3) is Pa-Aa+Po (
Ac-Ab-Aa)=Pb(Ac-Ab).

By adding minus Pa-Aa to both sides, we get (Pa
-Pb)Aa0Po (Ac-Ab-Aa)=Pb (
Ac-Ab-Aa) (Pb-Pa)/(Po-Pb) = (Ac-Ab-Aa)/Aa=constant=K2.

Next, the main flow rate from port 43 is Qa, the pilot flow rate of the pilot operated valve is Qb, and C is a constant. rY Ding: Lower a = (4) From (4), Sa/Sb = -Pa)/ (Po-Pb)
-FπT-, Qa/Qb=(C-3o-FT) Seal=1 piece/(C-8
a-1 block below-] "[) (So/5a) fl-"π go --- (5) Now, 5O1
Looking at Sa, it is proportional to the stroke X of the valve 46, so if its constant is mn, then So=mx
, 5a=nx.

S o / S a = m / n = constant (5), Q a / Q b = (m / n)
becomes constant, and the main flow rate Qa is the pilot flow JIQb
is proportional to. When the pilot flow iQb is determined, the main flow rate Qa is independent of the pressures of Po and Pa5Pb (determined).Here, the pilot flow ff1Qb is controlled using a pressure-compensated pilot operating valve (Japanese Patent Application No. 6O-268925). For example, since the pilot flow JIQb is constant regardless of the pressures of POlPa and Pb, the main flow rate Qa
also remains constant regardless of the pressures of Po, Pa, and Pb.

It goes without saying that the flow control valve 7 and the contaminant tank 8 may be replaced without being limited to the above embodiment, and that flow control valves having other structures may be used.

(Effects of the Invention) As explained above, according to the present invention, contaminant oil ranging from low concentration to high concentration can be freely produced even during operation of the hydraulic pump. In addition, since no contaminants are put into the tank, the pump will not be affected by contaminants, so there will be no shortening of its life or failure.Furthermore, if the flow rate is controlled by a pilot operated valve, the pump will not be affected by contaminants. Regardless of the pressure of the product, the excellent effect is that the oil from the hydraulic pump and the oil with the contaminant concentration from the contaminant tank are easily mixed and supplied to the test product.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of an embodiment of the present invention. Fig. 2 is a sectional view of a flow control valve according to an embodiment of the invention. Fig. 3 is an overall configuration diagram of a conventional system. 1. Oil tank. 2. Hydraulic pressure. Pump, 4.7...Flow rate control valve, 4a, 7a...Pilot operation valve, Figure 1 Figure 3 Sample, flow path, pollutant tank, filter, ・Free piston,

Claims (1)

[Claims] In a hydraulic circuit contaminant mixed oil supply system that tests the durability of a specimen consisting of a hydraulic pump and an oil tank, a flow control valve installed in the flow path between the pump and the specimen, and a flow control valve. A flow control valve and a contaminant tank are arranged between a flow path branching from the upstream of the flow control valve and a flow path downstream of the flow control valve, and a pilot operated valve that controls the flow rate of the flow control valve. Hydraulic circuit contaminant mixed oil supply device.