BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

The invention pertains to the field of butterfly valve shafts. More particularly, the invention pertains to a flexible member between two butterfly valve shafts on a common axis.

DESCRIPTION OF RELATED ART

Figure 5 shows a sectional view of a conventional dual butterfly valve with two butterfly valve discs attached to one shaft, of a sort which might be used in a manifold on an engine.

The valve has a body 2 with two flow passages connected to the manifold - a first flow passage 3 and a second flow passage 4 - extending there through. A first butterfly valve disc 5 is rotatable and is supported in first flow passage 3 for controlling fluid flow through the first flow passage 3. A second butterfly valve disc 6 is rotatable and is supported in second flow passage 4 for controlling fluid flow through the second flow passage 4.

Each of the valve discs 5, 6 receives a shaft 11. The shaft 11 supports and journals the valve discs 5, 6 for rotation in the body 2. The axis of rotation of the valve discs 5, 6 extends transversely. The shaft 11 is secured to the first disc 5 through a first pin 13 and to the second disc 6 through a second pin 14. The shaft 11 is driven by an electric motor or hydraulic servo actuator (not shown).

Multiple bearings 17, 18, 19 are present within the body 2 to support the shaft 11. Suitable packing 21 is provided at the ends of the shaft 11 for preventing leakage about the shaft 11 and between the openings provided in the body 2 for receiving the shaft 11.

When the shaft 11 is rotated by the electric motor or hydraulic servo actuator (not shown), both of the butterfly valve discs 5, 6 open and close at the same time. With a single shaft 11 controlling two discs 5, 6 extensive processing techniques are required to get both discs 5, 6 to seal at the same time. Also, thermal expansion differences play a role with a single shaft 11

SUMMARY OF THE INVENTION A first disc of a dual butterfly valve is mounted on a first shaft, and a second disc of the dual butterfly valve is mounted to a second shaft coaxial with the first shaft. The first shaft is connected to the second shaft through a flexible member. When the first shaft is rotated, the first shaft rotates the first disc towards a closed position and the rotation of the first shaft is translated to the second shaft through the flexible member, building tension in the flexible member and causing the second disc to rotate to a closed position prior to the first disc. The first disc then rotates to a closed position. The flexible member permits some lag to be present between the first disc and the second disc in moving to the open or closed position.

BRIEF DESCRIPTION OF THE DRAWING Fig. 1 shows a perspective view of a dual butterfly valve.

Fig. 2 shows a perspective cut through of Figure 1 along line 2-2.

Fig. 3 shows the two butterfly shafts coupled together through a flexible connection.

Fig. 4 shows a cross-section of the discs along a shaft.

Fig. 5 shows a sectional view of a conventional dual butterfly valve with one shaft. Fig. 6 shows a two butterfly shafts coupled together through an alternate flexible

connection.

DETAILED DESCRIPTION OF THE INVENTION

Figures 1-4 and 6 show a dual butterfly valve connected to a manifold of an engine. The valve has a body 102 with two flow passages coupled to the passages in manifold - a first flow passage 103 and a second flow passage 104 - extending there through. A first butterfly valve disc 105 is rotatable and is supported in a first flow passage 103 for controlling fluid flow through the first flow passage 103. A second butterfly valve disc 106 is rotatable and is supported in a second flow passage 104 for controlling fluid flow through the second flow passage 104. Each of the valve discs 105, 106 has a central hub portion 107, 108 having an opening 109, 110 for receiving a first shaft 111 or a second shaft 112. The first shaft 111 supports and journals the first valve disc 105 for rotation within the body 102 and the second shaft 112, coaxial with the first shaft 111, supports and journals the second valve disc 106 for rotation in the body 102. The axis of rotation of the valve discs 105, 106 extends transversely. The first shaft 111 is secured to the first disc 105 through a first pin 113. The second shaft 112 is secured to the second disc 106 through a second pin 114. The first shaft 111 is driven by an electric motor or hydraulic servo actuator, or pneumatic actuator (not shown). A second end 11 lb of the first shaft 111 and a first end 112a of the second shaft 112 are connected through a flexible member 120, so that when the electric motor, hydraulic servo actuator, or pneumatic actuator rotates the first shaft 111, the flexible member 120 translates rotational torque from one shaft to the other, and thus the second shaft 112 is driven by the electric motor, hydraulic servo actuator, or pneumatic actuator through the flexible member 120. The flexible member 120 is on a common axis of the first shaft 111 and the second shaft 112. The flexible member 120 is made of a material which is flexible. The geometry of the flexible member 120 is variable and can translate rotational torque from one shaft to the other. The flexible member 120 may be a flat spring as shown in Figures 2-3. In an alternate embodiment, the flexible member 120 may be a keyed round pin as shown in Figure 6.

The shape of the first and second butterfly valve discs 105, 106 is complementary to the configuration of the flow passages 103, 104. The outer perimeter 115, 116 of the first and second butterfly valve discs 105, 106 seats and seals against the flow passages 103, 104 in the body 102.

A first bearing 117 in the body 102 receives a first end 11 la of the first shaft 111. A second bearing 118 is present in the body 102 between the flow passages 103, 104 and receives a second end 11 lb of the first shaft 111 and a first end 112a of the second shaft 112. The second end 112b of the second shaft 112 is received by a third bearing 119. Suitable packing 121 is provided at, at least the first end 111a of the first shaft 111 (not shown) and the second end 112b of the second shaft 112 for preventing leakage about the shafts 111, 112 and between the openings provided in the body 102 for receiving the shafts 111, 112. When the electric motor, hydraulic servo actuator, or pneumatic actuator (not shown) drives the first shaft 111 and the first disc 105 towards seating, the flexible member 120 flexes, and as the first shaft 111 continues to rotate the first disc 105 toward a position in which the first disc 105 closes the first flow passage 103 through seating, the flexing of the flexible member 120 rotates the second shaft 112 and thus the second disc 106, causing the second disc 106 to rotate to a position in which the second disc 106 closes the second flow passage 104 through seating prior to the first disc 105 seating. As the first disc 105 continues to rotate toward the position in which the first disc 105 closes the first flow passage 103 through seating, tension is introduced and stored in the flexible member 120 until the first disc 105 rotates to a position in which the first disc 105 closes the first flow passage 103 through seating of the first disc 105. A slight rotation lag is present between the two discs 105, 106. The lag present is the amount of lag needed to ensure disc seating due to tolerance stack up. The lag would preferably be less than a few degrees of additional rotation. Figure 4 shows the first disc 105 and the second disc 106 relative to the sealing direction. It should be noted that the lag between the first disc 105 and second disc 106 is exaggerated in the drawing.

Similarly, when the electric motor, hydraulic servo actuator, or pneumatic actuator (not shown) drives the first shaft 111 and the first disc 105 to open, the flexible member 120 un-flexes (removes the tension on disc 106), and as the first shaft 111 continues to rotate the first disc 105 to a position in which the first disc 105 opens the first flow passage 103 completely, the flexing of the flexible member 120 rotates the second shaft 112 and thus the second disc 106, causing the second disc 106 to rotate to a position in which the second disc 106 opens the second flow passage 104 completely. A slight rotation lag is present between the two discs 105, 106.

By having two different shafts and connecting the shafts through a flexible member, manufacturing and assembling of the dual butterfly valve discs is easier than affixing two valve discs on one common shaft within the manifold. Accordingly, it is to be understood that the embodiments of the invention herein described are merely illustrative of the application of the principles of the invention. Reference herein to details of the illustrated embodiments is not intended to limit the scope of the claims, which themselves recite those features regarded as essential to the invention.