JPH0147675B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fluid check valves, and more particularly to fluid check valves suitable for use in compressor bleed systems in gas turbine engines.

It is common practice to bleed compressor power from the compressor of a gas turbine used as propulsion power for jet aircraft. Air bled from the compressor can be used to prevent engine surge during start-up or acceleration conditions, to heat the aircraft cabin, or to blow air onto aircraft wings or other surfaces to prevent icing. used for heating. Systems for bleeding compressor output typically include check valves to prevent backflow through the bleed system in the event of a failure of one of the engines, for example when a multi-engine bleed system is used. Without this backflow prevention feature, air bled from the operating engine could flow into the failed engine, thereby interfering with the operation of the auxiliary heating devices described above. Check valves used in such air bleed systems must be capable of withstanding air flows at pressures of around 20 bar and temperatures of around 430°C, and must be able to close quickly in the event of backflow. .

Known check valves used in compressor bleed systems have typically been of the flapper type. However, the flap type valve is characterized in that the supporting area of the valve body is small relative to the area of the flow path. A small support area tends to cause the valve seat to wear out over a short period of time due to repeated impacts between the valve body and the valve seat, impairing the durability of the check valve. An example of a known flapper type check valve for use in compressor bleed systems is disclosed in US Pat. No. 2,925,825. Although various types of check valves are known, many have constricted or tortuous flow paths that create undesirable pressure drops. US Patent No.
No. 2927604 and No. 2928417 disclose check valves that take such points into consideration. Further, while U.S. Pat. No. 3,134,394 discloses a check valve that generates a smaller pressure drop than the one described above, the check valve based on the present invention has a significantly smaller pressure drop and backflow. It is believed that this can be prevented more quickly.

In view of the above, the main object of the present invention is to provide an improved check valve in which the valve body is supported by a substantially large support surface so that wear due to flapping and its impact is reduced. It is in.

A second object of the present invention is to provide an improved check valve in which the degree of constriction of the flow path is small and the flow path is not tortuous.

A third object of the invention is to provide an improved check valve with low pressure drop.

A fourth object of the present invention is to provide an improved check valve capable of rapid and controlled closure of a flow path under backflow conditions.

The check valve according to the invention comprises an aerodynamic perforated guide body defining a streamlined central body supported in the housing by struts capable of absorbing thermal stresses adequately, as well as an aerodynamic poppet type. It is equipped with a valve body. The valve body and housing define a flow path having a generally constant cross-sectional area over its entire length. The forward flow within the check valve opens the valve body, which abuts the front face of the perforated guide body. The flow in the opposite direction in the check valve flows into the hole in the perforated guide body and then hits the concave surface of the valve body and immediately brings it into contact with the valve seat, so that the flow in the check valve is blocked. . A diving cylinder and a sleeve are provided inside the perforated guide body, and since the valve body is fixed to either the cylinder or the sleeve, the valve body is preferably moved for damping movement between the cylinder sleeves. vibration and shock loads are kept to a minimum. Holes are drilled in the cylinder to reduce the spring constant between cylinder and sleeve, thereby preventing the valve body from jumping when the valve opens.
The holes in the cylinder also have the function of reducing the negative pressure generated within the cylinder and preventing the closing movement of the valve from being inhibited. In the preferred embodiment described below, the sleeve is closely fitted to the cylinder so that the cylinder and sleeve provide a large support surface for movement of the valve body within the check valve. Undesirable bouncing or other vibrations are prevented.

In the drawings, the check valve according to the invention is generally designated by the reference numeral 1.
0 and has a housing 15 with flanges 20, 25 at both ends for mechanically coupling the check valve between two opposing ducts. The housing also has an annular valve seat 30 in its interior against which a poppet-type valve body 35 abuts for closing the check valve under backflow conditions. This reverse flow refers to the flow from left to right in Figure 1.

The aerodynamic perforated guide body 45 has a streamlined shape so as to have a low resistance to forward flow, and the strut 40
is supported within the housing 15 by. Second
As clearly shown in the figures, the struts extend between the housing and the perforated guide in an orientation that includes both radially outward and tangential components from the perforated guide. Because the struts are oriented in this manner, distortions due to thermal expansion and fluid loads are absorbed by bending deformation of the struts, and excessive stress is generated in the portions where the struts are connected to the housing and the perforated guide body. Never.

The perforated guide body 45 has a front face 50 and a rear face 55 for forward flow which can be secured at a portion 58 by suitable fasteners such as welding, brazing or riveting.
are connected at. The front surface 50 and the rear surface 55 have holes 60 and 65, respectively, and are configured to receive flow in the opposite direction so as to bring the valve body 35 into contact with the valve seat 30 in the case of reverse flow. Valve body 35
The state in which the valve is in contact with the valve seat 30 is shown by phantom lines in FIG. Hole 6 as shown
The hole 5 is smaller than the hole 60, and is arranged approximately at the center of the front or rear surface, respectively. Although this selection of hole placement and dimensions is appropriate for a check valve for a compressor bleed system in a gas turbine engine, the check valve embodiments of the present invention are not limited thereto. Rather, it should be understood that the arrangement and size of the holes are appropriately selected depending on the operating temperature and pressure of the fluid of interest and the type of fluid.

The perforated guide body 45 has a generally conical front and rear surface, and is adapted to allow a diving cylinder 70 to be attached along the central axis inside thereof. The cylinder has a bore 75 at its downstream end and a sleeve 85 fitted therein generally closely. This cylinder and sleeve constitute a damping device for alleviating the vibration and impact of the valve body.
The hole 75 also has the function of weakening the spring constant between the cylinder sleeves and preventing the valve body from jumping when the valve is opened. The hole 75 also promotes air flow into the cylinder when the flow path is closed and prevents negative pressure from being generated in the cylinder that would prevent the valve from closing.

The valve body 35 has a generally conical shape and is secured to the end of the sleeve 85 by bolts 90 and nuts 95 or the like in any suitable manner. In a preferred embodiment, the cylinder and sleeve both extend substantially the entire length of the check valve, and these members slide against each other to provide a very large support surface for the valve disc. It can be seen that bouncing or other vibrations are prevented.

The outer periphery of the valve body 35 is aligned with the valve seat 30 as shown by phantom lines in FIG. 1 when the check valve is closed.
in close contact with. As clearly shown in FIG. 1, the valve body 35 forms a concave shell body toward the downstream, and the forward flow within the check valve hits the convex surface on the outside of the valve body and prevents the non-return. When the valve is opened, the inner concave surface of the valve body covers the front surface of the perforated guide body. The flow in the opposite direction inside the check valve flows through the holes 65 and 60 of the perforated guide body, hits the concave surface inside the valve body 35, and pushes the valve body against the valve seat 3.
0 to close the check valve. 1st
As clearly shown in the figure, the rear surface 55 of the perforated guide body and the valve body 35 are generally conical so that when the check valve is open, a generally conical center body is formed within the check valve. Determine. This center body and housing 1
5 defines a flow path 100 having a generally constant area from one end to the other end of the check valve. It can be seen that the pressure drop in the check valve according to the present invention is small because the flow is uniform along the streamlined central body formed by the perforated guide body and the valve body.

One of the features of the check valve according to the present invention is that the pressure drop is small. The entire opening and closing movement is damped by the sleeve and cylinder mechanism, which provides a large support surface for the reciprocating movement of the valve body. A hole 75 in the cylinder prevents the valve body from jumping and prevents negative pressure from building up in the cylinder and interfering with the closing action of the check valve. Since the sliding surface between the cylinder and the sleeve is disposed within the perforated guide body, its entire length is protected against intrusion of foreign matter and other contamination. The holes drilled in the front and rear surfaces of the perforated guide body 45 enable the check valve to close quickly even under relatively small backflow. Furthermore, since the valve body is made of a concave shell body and can effectively catch backflow, it becomes possible to quickly close the check valve against backflow.

The check valve according to the present invention described above is operated only by the flow of fluid inside the check valve without using any special actuator or other auxiliary means, but it may be operated using a spring, actuator or other auxiliary means as desired. It goes without saying that auxiliary means can also be used.

Although the present invention has been described above with reference to its preferred embodiments, it will be apparent to those skilled in the art that various modifications and changes can be made without departing from the concept of the present invention as set forth in the claims.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of a check valve according to the present invention;
1 is an end view of the check valve shown in FIG. 1, and FIG. 3 is a sectional view showing the other end of the check valve shown in FIG. 10...Check valve, 15...Housing, 20,
25...flange, 30...valve seat, 35...valve body, 40...strut, 45...perforated guide body, 50...front surface, 55...rear surface, 58...portion, 60, 65... Hole, 70... Cylinder, 75
...hole, 85 ... sleeve, 90 ... bolt, 9
5...Natsuto, 100...Flow path.

Claims (1)

[Claims] 1. A housing 15 defining the outer surface of the flow path;
A valve seat 30 disposed within the housing is configured to close the flow path by engaging with the valve seat under reverse flow conditions and open the flow path by moving away from the valve seat under forward flow conditions. a valve body 35 displaceable within the housing by fluid flow; a front face 50 and a rear face 55 having holes 60, 65; a stationary guide configured to cooperate with the inner surface of the flow passage to define the inner surface of the flow passage, to receive backflow through the holes 60, 65, and to engage the valve body with the valve seat to close the flow passage; body 45
and, wherein the valve body 35 includes a concave shell with an open inner side, and when the valve body is in the open position, fluid flowing downstream through the valve is allowed to pass through the valve. The guide body is configured to impinge on an outer surface of the valve body that is not engaged with the valve seat, such that a front surface 50 of the guide body is received within at least a portion of the interior of the valve body, thereby placing the valve body in an open position. 1. A fluid check valve characterized in that the valve body is supported near the front face of the valve body so that the valve body does not displace radially when the valve body is in position.