JPS6333593B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to exhaust valves for use in hydraulic systems.

Many hydraulic systems have problems with air and other gases accumulating within the system. When a portion of a volume containing oil or other liquid is filled with air or other gas, the compressibility and elasticity of the air will prevent the system from operating if the system is pressurized. descend. This air typically enters the system when the system is depressurized, particularly when the fluid in the system is brought to a pressure below atmospheric pressure, creating a negative pressure through its airtight seal. Become. This situation is particularly problematic in telescoping hydraulic cylinders because of their multiple sliding seals, but air can also enter from other areas such as the sump and return passage.

Since these air and gases collect at the highest point of the hydraulic system, an exhaust valve is generally located at the highest point. This valve is manually opened when the hydraulic system is pressurized at the beginning of operation, and manually closed after the air has been expelled to begin passing liquid within the hydraulic system. Because the valve is located at the highest point in the hydraulic system, it is difficult and cumbersome to access it for manual operation, and it is necessary to visually confirm when air is vented and fluid leaks through the valve. They tend to leak excess liquid, and as this liquid is always led into the liquid reservoir, they tend to introduce dirt, etc., and therefore the area around them has to be cleaned regularly. It was hot. Furthermore, since the exhaust valve operation must be done on a daily basis and requires at least two people to do it effectively, it is possible to eliminate the operation and remove some air in the system. There is a tendency to operate the system while it is present, which tends to reduce the efficiency of the system and cause significant wear and tear on certain parts of the system.

In this regard, valve systems have been developed that automatically vent gases such as air within hydraulic systems.

One typical example is to allow gas, such as air, within the hydraulic system to escape when the system is started to pressurize at the beginning of operation, and to When the liquid is about to be discharged, the pressure of the liquid moves the valve member of the valve device to close the discharge opening, thereby preventing the liquid from being discharged.

However, such a device has the following problems. That is, if the pressure in the hydraulic system decreases, the valve member will be displaced accordingly, thus opening the discharge opening, so that even if a temporary pressure drop occurs, the discharge will not occur. If the opening is released and the fluid pressure increases again,
There is a risk that the liquid may leak outside through the discharge valve.

In view of the above points, the present invention automatically discharges the gas in the hydraulic system when it starts operating, and once the gas is discharged, the pressure in the system increases. An object of the present invention is to provide an exhaust valve for a hydraulic system that will not be released even if the pressure temporarily decreases.

That is, the exhaust valve according to the present invention is an exhaust valve for exhausting gas such as air from a pressurized hydraulic system and preventing liquid from being discharged from the system, and the exhaust valve comprises: a valve member; A first hole provided from one end of the valve member toward the center, and a second hole provided from the opposite end of the valve member toward the center, the inner surface of which is threaded. a second hole that is connected to the first hole; an intermediate hole that communicates the first and second holes; a valve seat provided at a connecting portion between the first and second holes and the intermediate hole; provided on the first end side of the hole;
an orifice that restricts the flow of fluid entering the hole; and a spherical first valve body that is provided between the valve seat and the orifice in the first hole and has a higher density than the liquid; a first valve element that is movable between the seat and the orifice by a distance equal to at least the diameter of the valve element; a second spherical valve body that can be fitted together; a plug that is threadedly engaged with the screw in the second hole; a second valve body that is provided between the plug and the second valve body; It has a spring that presses the valve body against the valve seat of the second hole, and a passage that communicates the second hole with the atmosphere.

The exhaust valve according to the present invention has the above configuration, and if the exhaust valve is set at an appropriate location in the hydraulic system, the hydraulic system starts operating and its internal pressure increases. Even if the gas in the system is passed through the valve, thereby
The first valve body never engages its seat, allowing gas to pass around the second valve body and out, and liquid within the system being forced out following the gas. When this occurs, the first valve body is displaced by the viscosity of the liquid and engages the valve seat, closing the discharge valve and preventing discharge of the liquid.

In such a situation, even if the pressure in the hydraulic system decreases, the second valve body engages with its valve seat, preventing gas such as air from entering the system from outside. be done. However, depending on the degree of pressure drop, the first valve body may separate from the valve seat. Therefore, in such a state, if the hydraulic pressure in the system increases, there is a risk that the second valve element will be separated from its valve seat and the liquid will be discharged to the outside through the valve. In response to such a situation, the exhaust valve according to the present invention has the following features:
After automatic gas evacuation as described above, the plug is rotated and displaced into the second hole, thereby increasing the pressure of the spring between the plug and the second valve body. Such situations can be avoided.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

FIG. 1 shows a typical usage example of the exhaust valve according to the present invention. Shown here in cross section is the upper end of the hydraulic cylinder 10. This cylinder has a cavity 11 which is normally filled with operating fluid, but since it is located at the upper end of the hydraulic system, air in the system has a tendency to collect and stagnate. There is.

The illustrated hydraulic cylinder has a hole 1 opening into a cavity 11.
2, and is adapted to receive an exhaust valve 13. Externally of the bore 12 is a conical seat 14, a threaded bore 16, and an end surface that provides an evacuation clearance when the valve is assembled in the operating position. 1st
Exhaust valve 13 in the operating position as shown in the figure
is tilted at an angle from the vertical position, but the axis of the exhaust valve is within 60 degrees in order to properly operate the exhaust valve as an automatic valve, as will be explained in more detail below.

The exhaust valve 13 is shown in detail in FIG. As shown, the valve is constructed from a single rod;
A valve member 20 having a cylindrical outer circumferential surface 21 that fits tightly within the hole 12 is provided at its lower end. This outer circumferential surface 21 is provided with a groove 22 in which an O-ring 23 and a support ring 24 are received to provide a proper sealing engagement with the bore 12. A conical shoulder 26 is provided above the outer circumferential surface 21, which rests on the seat 14 in the hydraulic cylinder and acts as an additional seal and stop. A screw portion 27 is provided above the shoulder portion 26, and this screw portion is screwed into the screw hole 16 described above. Further above, there is a small diameter exhaust groove 28.
and a hexagonal head 31 for engaging a wrench. An end surface 32 is provided at the top end of the valve member 20 and has a chamfer 33.

The valve member 20 has in its intermediate portion a central axial hole or passageway 35 coaxial with the outer circumferential surface, which hole acts as a flow path between the two exhaust sections of the exhaust valve. At the lower end of the hole 35 is a conical valve seat (or first valve seat) 36, and below it is a large diameter hole or first chamber 37. The hole has a length approximately twice its diameter for reasons detailed below. A second larger diameter hole 38 is provided at the lower end of the hole 37, and the hole 38 has a lip 4 provided at the end of the valve member.
An orifice plate 40 is housed therein, which is held in place by 1. The orifice plate has an orifice 43 provided in the center and a substantially conical seat 44 provided on the inner surface. A first or spherical valve body 45 is disposed within the bore 37 and is positioned at a seat 44 on the orifice plate 40.
and the valve seat 36. Orifice plate 40 includes first chamber or hole 37
forming a restricted entrance.

Valve member 20 has at its upper end an upper bore or second chamber 48 which is connected to central bore 35 at a second or conical seat 49 . Directly above the valve seat 49 are a plurality of radial exhaust passages or second passages 51 extending from the upper hole 48 to the exhaust grooves 28 on the outer surface of the valve member. The exhaust channels are arranged symmetrically around the hole, and their number and diameter are selected to provide a predetermined flow restriction, as will be explained in more detail below.

The upper end of the upper hole 48 is connected to a screw hole 53 extending to the end surface 32, and a second valve element, that is, a spherical valve element 55 is housed in the upper hole, and the valve seat 4
9 in sealing engagement. plug 56
is provided in the bore 53 and is movable in the axial direction towards and away from the valve body 55. The plug 56 is provided with a socket 57 to be rotated by a wrench, and
It has a conical portion 58 and a central projection 60.
The central projection 60 has a flat end surface 61 and a spring 6
3 is set around this protrusion 60 and abuts the conical part 58 of the plug at one end and the valve body 5 at the other end.
5, thereby causing the valve body 55 to engage with the valve seat 49.
biased into a position of sealing engagement. Axial movement of plug 56 adjusts the force applied by spring 63 and determines the opening force required to move valve body 55 from valve seat 49. Further, the exhaust valve can be reliably closed by screwing the plug 56 inward so that the end face 61 of the central protrusion 60 presses the valve body 55 against the valve seat 49.

The operation of the valve according to the invention is best illustrated in FIGS. 3 and 4. The exhaust valve is operated in a nearly vertical position (not tilted more than 60° from vertical position). However, this valve has been found to operate at an angle of up to 90 degrees from the vertical position. Normally, when the hydraulic system is not pressurized, the valve is in the state shown in FIG.
Prevent air flow to and prevent air from entering.
The lower valve body 45 normally engages the conical seat 44 of the orifice 40, but no sealing is required at this point. The valve is connected to the seat 44 by means such as a notch in the seat 44 or by making the orifice 43 non-circular.
4 and the valve body 45, it would be practical. However, the presence or absence of a seal at this point does not affect the operation of the valve. This is because only the force of gravity holds the valve body 45 in its lower position.

When the hydraulic system is pressurized, liquid or gaseous fluid moves the valve body 45 toward the seat 44 as shown in FIG.
lift it from Then, for example, about 3.52Kg/cm ²
When the predetermined pressure of (50psi) is reached, the upper valve body 5
5 is separated from the valve seat 49 and the fluid is passed through the exhaust passage 51 into the atmosphere. As the pressure within the hydraulic system increases, the velocity of the air or gas flow increases linearly and the valve body 45 is held between the orifice plate and the valve seat 36. However, as soon as liquid begins to enter the valve through orifice 43, the viscosity of the liquid, which is greater than that of the gas, causes valve body 45 to move into sealing engagement with valve seat 36, as shown in FIG. This prevents liquid from leaking from the valve after the valve body 55 is brought into sealing engagement with the valve seat 49 by the spring 63. Therefore, as long as a certain pressure is maintained within the system, the exhaust valve will remain in the state of FIG. 4 and no fluid or gas will escape from the hydraulic system.

It may not be particularly clear why the valve body 45 does not seal against the valve seat 36 even under relatively high air velocities. As a result of experiments, it was found that the size of the valve body 45 is almost the same as that of the hole 37, and the length of the hole 37 is changed from the lower position adjacent to the orifice plate 44 to the upper position adjacent to the valve seat 36 to the diameter of the hole. It turns out that it is important to have a length that allows movement at least a distance equal to . Additionally, it has been found to be important to provide a restriction at orifice 43 and other restrictions downstream of central hole 35. In this experiment, the valve was designed with a 9.5 mm (0.375 inch) diameter valve body and a diameter
11.1 mm (0.437 inch) hole 37.
In addition, four exhaust passages 51 are provided, approximately 3.6 mm (0.14 mm).
(inch) diameter. Under such conditions,
After experimenting with orifices 43 of different diameters, the best results were obtained when the orifice diameter was 4.7 mm (0.187 inch). Further reducing the diameter of the orifice 43 will only result in a reduction in the velocity of air flow at a given pressure level, and enlarging the orifice 43 will cause the valve body 45 to engage the valve seat 36 and close the valve prematurely. result. Therefore, the orifice 43 has been enlarged to the point where it does not provide any restriction, and the biasing force of the spring 63 is such that the upper valve body 55 is approximately 3.52 mm
When adjusted to allow opening at ⁵⁰ psi, air initially flows, but as the pressure increases to 100 psi, the lower valve body 45 seals against the valve seat 36.
This prevents further air from escaping. Furthermore, even with the best flow at an orifice of approximately 4.7 mm (0.187 inch) as described above, if plug 56 and valve body 55 are removed, the flow will enter center hole 35 and proceed straight through threaded hole 53 to the outside. Once again, the valve closes prematurely.

However, if maximum air flow is not required, the embodiment shown in FIG. 5 can also be used. The embodiment of FIG. 5 is substantially the same as the embodiment shown in FIGS. 1-4, except that orifice plate 40 is not provided. In this embodiment, the lower end of the valve has hole 37.
It has a hole 66 with the same diameter. This hole 66 is hole 3
7, it extends to the lower end surface 67 of the valve member 20. In order to hold the spherical valve body 45 in a predetermined position within the bore 66, the valve member is provided with a transverse hole 69 in which a retaining pin 70 abuts the valve body 45 in the lower position. It is stored. Retaining pin 70
The diameter of the valve body 45 is such that it provides some restriction to the flow so that the valve body 45 does not close the valve prematurely. It does not act to provide flow.

FIG. 6 shows a mounting arrangement for an exhaust valve for situations where it is impractical to mount the exhaust valve directly into the cylinder. In this case, the hydraulic cylinder 72 is provided with an exhaust fitting 73, and a flexible hydraulic hose 74 is attached to the fitting. A manifold 75 is attached to a vertical member 76 separate from cylinder 72 by means such as bolts 77. The manifold 75 has a metal fitting 79 at its lower end, and one end of the hose 74 is connected to this metal fitting. The exhaust valve 80 according to the present invention is mounted in the upper opening of the manifold, and its lower end is connected to the hose 74.
through which fluid enters the manifold.

[Brief explanation of the drawing]

Fig. 1 is a partially sectional side view showing the exhaust valve according to the present invention attached to a hydraulic cylinder of a hydraulic system; Fig. 2 shows the exhaust valve of Fig. 1 not yet under pressure; A cross-sectional side view showing the
Figure 4 is a cross-sectional side view showing the exhaust valve in a state where air is exhausted from the hydraulic system; Figure 4 is a cross-sectional side view showing the exhaust valve closed by the pressure of the hydraulic system; Figure 5 is Fig. 6 is a cross-sectional side view of the exhaust valve according to the embodiment; Fig. 6 is a side view showing the exhaust valve installed at a position away from the hydraulic cylinder; 10...Hydraulic cylinder, 11...Vacancy, 13...
...exhaust valve, 35...first passage, 36...first valve seat, 37...first chamber (hole), 45...
... Spherical valve body (first valve body), 48 ... Second chamber (hole), 49 ... Second valve seat, 51 ... Second passage (exhaust path), 55 ... Second chamber Valve body, 63...
Biasing means (spring).

Claims (1)

[Scope of Claims] 1. An exhaust valve for exhausting gas such as air from a pressurized hydraulic system and for preventing liquid from being discharged from the system, comprising: a valve member; the valve member; a first hole provided from one end toward the center; and a second hole provided from the opposite end of the valve member toward the center, the inner surface of which is threaded. a second hole; an intermediate hole that communicates the first and second holes; a valve seat provided at a connecting portion between the first and second holes and the intermediate hole; provided on the first end side, the first
an orifice for restricting the flow of fluid entering the hole of the valve; a first valve body that is movable between the seat and the orifice by a distance equal to at least the diameter of the valve body; a second spherical valve body capable of mating; a plug threadably engaged with the screw in the second hole; a second valve body provided between the plug and the second valve body; An exhaust valve for a hydraulic system, the exhaust valve having: a spring pressing a valve body against the valve seat of the second hole; and a passage communicating the second hole with the atmosphere.