Tuning screw assembly
View Patent ↗The present invention relates to a tuning screw assembly comprising a sleeve ( 100 ) with internal threads for engaging a tuning screw ( 200 ) having external threads. The sleeve comprises a first threaded portion ( 32 ) which is axially displaced in relation to a second threaded portion ( 34 ) for frictionally locking said screw body in said sleeve. The invention also relates to a method of manufacturing said friction locking sleeve and to a resonator comprising said friction locking sleeve.
1. A tuning screw assembly in combination with a resonator having a resonator cavity inside a frame or housing ( 400 ), comprising a stationary, internally threaded sleeve member ( 100 ) being in threaded engagement with a central, externally threaded tuning screw member ( 200 ), which extends into said resonator cavity and is rotatable within said sleeve member against a frictional locking force exerted between the mutually engaging threads so as to adjust the resonating frequency of said resonator, characterized in that
the sleeve member ( 100 ) comprises a first axial part ( 1 ) provided with a first threaded portion ( 32 ), an unthreaded intermediate axial part ( 2 ), and a second axial part ( 3 ), which is provided with a second threaded portion ( 34 ), wherein said sleeve member ( 100 ) has a substantially uniform cylindrical outer shape, is formed of a single integral piece, and is provided with at least one tapered slot ( 10 , 12 ) through the wall thereof in said unthreaded intermediate axial part ( 2 ), so as to make the unthreaded intermediate axial part ( 2 ) resilient in the axial direction,
said first and second threaded portions ( 32 , 34 ) of the sleeve member ( 100 ) are axially misaligned relative to each other in such a way that they do not fit exactly with the external thread ( 23 ) of the tuning screw ( 200 ),
said first axial part ( 1 ) of the sleeve member ( 100 ) is attached to said resonator frame or a housing ( 400 ), whereas
said second axial part ( 3 ) of the sleeve member is resiliently movable in the axial direction, because of the resiliency of the intermediate axial part ( 2 ), so as to engage with the external thread ( 230 ) of the screw member ( 200 ) and achieve said frictional locking force upon adjustment of the resonating frequency of said resonator.
2. The tuning screw assembly in combination with a resonator according to claim 1 , wherein a frictional reducing agent is applied to any of the mutually engaging threads.
3. The tuning screw assembly in combination with a resonator according to claim 1 , wherein said unthreaded intermediate axial part ( 2 ) comprises an internal recess ( 40 ) in the wall of the sleeve member ( 100 ).
4. The tuning screw assembly in combination with a resonator according to claim 1 , wherein said slot ( 10 , 12 ) extends substantially circumferentially in said wall.
5. The tuning screw assembly in combination with a resonator according to claim 1 , wherein the sleeve member ( 100 ) is axially shorter than the central screw member ( 200 ).
6. The tuning screw assembly in combination with a resonator according to claim 1 , wherein said first axial part ( 1 ) of the sleeve member ( 100 ) is shaped so as to enable mounting thereof in said frame or housing ( 410 ) with a press fit.
7. The tuning screw assembly of claim 1 , wherein the sleeve member ( 100 ) is provided with more than one slot ( 10 , 12 ).
8. A resonator comprising a tuning screw assembly ( 100 , 200 ) as defined in claim 1 , said sleeve member ( 100 ) being securely fastened to a said frame or housing ( 400 ) of the resonator.
9. The resonator according to claim 8 , wherein said sleeve member ( 100 ) is fastened to a wall ( 410 ) of said housing ( 400 ) by a press fit.
10. The tuning screw assembly in combination with a resonator according to claim 1 , wherein said intermediate axial part ( 2 ) of the sleeve ( 100 ) is permanently deformed axially.
11. The tuning screw assembly in combination with a resonator according to claim 10 , wherein said intermediate axial part ( 2 ) is permanently compressed axially.
12. The tuning screw assembly in combination with a resonator according to claim 10 , wherein said intermediate axial part ( 2 ) is permanently expanded axially.
13. A method for manufacturing an internally threaded sleeve member ( 100 ) forming a part of a tuning screw assembly ( 100 , 200 ) in combination with a resonator having a resonator cavity inside a frame or housing ( 400 ), said assembly also including an externally threaded tuning screw member ( 200 ) for adjusting the resonating frequency of said resonator, said screw member extending into said resonator cavity, characterized by the steps of
providing first and second axial parts ( 1 , 3 ) of said sleeve member ( 100 ) with first and second internally threaded portions ( 32 , 34 ),
providing the sleeve member ( 100 ) formed of a single integral piece with an unthreaded intermediate resilient axial part ( 2 ) between said first and second internally threaded portions ( 32 , 34 ) and having at least one tapered slot ( 10 , 12 ) through the wall thereof in said unthreaded intermediate axial part ( 2 ) so as to make the unthreaded intermediate axial part resilient in the axial direction,
providing a relative axial misalignment of said first and second internally threaded portions ( 32 , 34 ) in such a way that they do not fit exactly with the external thread ( 230 ) of said tuning screw member ( 200 ), whereby a frictional locking of said tuning screw member is achieved when being in threaded engagement with said sleeve member, because of the resiliency of said intermediate axial part ( 2 ) of the sleeve member ( 100 ) and the axial deformation of said intermediate part, and
mounting said first axial part ( 1 ) of said sleeve member in said resonator frame or housing ( 400 ) so that said tuning screw member extends into said resonator cavity and enables a sustainable adjustment of the resonating frequency of said resonator.
14. The method of claim 13 , wherein the sleeve member ( 100 ) is provided with more than one slot ( 10 , 12 ).
15. The method according to claim 13 , wherein
said sleeve member ( 100 ) is first provided with a uniform internal thread, whereupon
said intermediate, resilient axial part ( 2 ) of the sleeve member ( 100 ) is permanently deformed axially so as to displace said first and second internally threaded portions ( 32 , 34 ) relative to each other.
16. The method according to claim 15 , wherein at least one slot ( 10 , 12 ) is made in said intermediate axial part ( 2 ) of the sleeve member ( 100 ) before it is deformed axially.
17. The method according to claim 13 , wherein said first and second threaded portions ( 32 , 34 ) are formed separately.
18. The method according to claim 17 , wherein said misalignment is provided when forming said first and second threaded portions ( 32 , 34 ).