WO2009033323A1

WO2009033323A1 - Lubricating sight dome and method of operating the sight dome

Info

Publication number: WO2009033323A1
Application number: PCT/CN2007/002711
Authority: WO
Inventors: Qiongyu Zhang; Jun Ni
Original assignee: Norgren LLC
Current assignee: Norgren LLC
Priority date: 2007-09-13
Filing date: 2007-09-13
Publication date: 2009-03-19
Anticipated expiration: 2010-03-13

Abstract

A lubricating sight dome and a method of operating the sight dome are disclosed. The sight dome (200) comprises an inner body (202), an outer body (204), an adjusting screw (206), a lower sealing member (208) and an upper sealing member (210). The sight dome (200) has multiple control features that control the flow rate of the lubricant. A first control feature controls the rate of flow of the lubricant over a first adjustment range and a second control feature controls the rate of flow of the lubricant over a second adjustment range.

Description

LUBRICATING SIGHT DOME AND METHOD OF OPERATING THE SIGHT DOME

BACKGROUND OF THE INVENTION Lubricators are typically used to add lubricant to a flowing stream of fluid. One type of lubricant is oil and one type of fluid is compressed air. Other types of lubricants and fluids may be used. Figure 1 is a cross sectional view of a typical lubricator. Compressed air flows into the lubricator at inlet port 116. The compressed air pressurizes the bowl 113 and forces oil 112 up through siphon tube 114. The oil 112 flows from siphon tube 114 into sight dome 108. Oil 104 drips from orifice 118,

' typically a needle valve, through an opening 110 in the bottom of sight dome 108, and into the flow of air 102. The lubricated fluid exits the lubricator through outlet port 118. An adjustment knob 106 is used to change the size of orifice 118 to control the rate of oil flowing into the air stream. Sight dome 108 is typically made from a transparent material that allows a user to see into sight dome 108 to visually confirm the flow rate of ¹ oil through sight dome 108.

There are a number of problems with using a needle valve as the orifice that controls the flow rate of lubricant through the sight dome. One problem is that needle valves may not be able to completely shut off the flow of lubricant through the sight dome. Another problem is that the tip of the needle valve and the mating body need to

■ be manufactured with close tolerances for the needle valve to work properly. This increases the cost of the sight dome. Another problem with needle valves is that it may take many turns of the valve adjusting knob to go from the completely closed position to the fully opened position.

■ ASPECTS

One aspect of the invention includes a sight dome having a hollow inner body with a top and a bottom where the top and bottom are open ended, characterized by: the open ended top of the inner body forming a bore where the bore has a top end and a main section and the top end of the bore has a larger diameter than the main section and where the main section is threaded and where at least part of the top end has a tapered surface; an adjustment screw having a top section and a bottom section and where the bottom section is threaded and configured to be screwed down into the threaded main section of the bore in the inner body, from the top of the inner body; an opening formed into the threads in the bottom section of the adjustment screw and coupled to an inner bore formed into a bottom end of the adjustment screw; a lower sealing member attached to the adjustment screw above the threaded bottom section and configured to seal against the tapered surface when the adjustment screw is screwed into a fully closed position, and where a gap is formed between the lower sealing member and the tapered surface when the adjustment screw is unscrewed from the fully closed position thereby allowing a fluid to flow from the top of the inner body, past the lower sealing member, through the opening and into the inner bore.

Preferably, a top edge of the opening is below a top edge of the threaded main section when the adjustment screw is screwed into the fully closed position.

Preferably, a top edge of the opening remains below a top edge of the threaded main section over a range of motion of the adjustment screw and where the range of motion starts at the fully closed position.

Preferably, the range of motion is selected from the group: 1/16 turn, 1/8 turn, ¹A turn, 3/8 turn, ^ιλ turn, ³A turn.

Preferably, a bottom edge of the opening is at least level with a top edge of the threaded main section when the adjustment screw is screwed into a completely opened position.

Preferably, the adjustment screw has a completely opened position and the adjustment screw moves from the fully closed position to the completely open position with a predetermined amount of rotation. Preferably, the predetermined amount of rotation is selected from the group: 1 turn, 1.5 turns, 1.75 turns, 2 turns, 2.25 turns, 2.5 turns, 3 turns.

Preferably, the sight dome further characterized by: a hollow outer body having a top and a bottom where the top and bottom are open ended and where the inner body is configured to fit inside the outer body forming a gap between the inner body and outer body; an upper sealing member attached to the top section of the adjustment screw above the lower sealing member and configured to form a seal against the hollow outer body.

Preferably, the sight dome further characterized by: a lubricator, where the bottom of the hollow outer body is attached to the lubricator capturing the inner body and adjustment screw inside the hollow outer body. Preferably, the inner body, the outer body and the adjustment screw are injection molded.

Preferably, the inner body, the outer body and the adjustment screw are fabricated from plastic.

Another aspect of the invention comprises a method of operating a sight dome, characterized by: controlling a flow rate of a lubricant flowing through the sight dome using a first control feature when an adjustment screw is in a first adjustment range; controlling the flow rate of the lubricant using a second control feature when the adjustment screw is in a second adjustment range.

Preferably, the method further comprises the first adjustment range partially overlaps with the second adjustment range.

Preferably, the method further comprises the first control feature is an interaction between a lower sealing member installed on the adjustment screw and a tapered surface formed in a bore in an inner body, and where the second control feature is a relationship between a top edge of an opening in a threaded end of the adjustment screw and a top edge of a threaded bore in the inner body.

Preferably, the method further comprises controlling the flow rate of the lubricant using the first control feature and a third control feature when the adjustment screw is in a third adjustment range.

Preferably, the method further comprises the third control feature is a torturous ^' path between threads on the adjustment screw and threads in a bore in an inner body.

Preferably, the method further comprises the third adjustment range is a subset of the first adjustment range. Preferably, the method further comprises the first control feature completely stops the flow of lubricant through the sight dome when the adjustment screw is at a first end of the first adjustment range.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a typical lubricator.

FIG. 2 is an exploded view of sight dome 200 in an example embodiment of the invention.

FIG. 3 is a cross sectional view of sight dome 200 in an example embodiment of the invention.

FIG. 4 is a cross sectional detailed view of sight dome 200 with adjustment screw 206 located in the fully closed position in an example embodiment of the invention.

FIG. 5 is a cross sectional detailed view of sight dome 200 with adjustment screw 206 located in a partially open position in an example embodiment of the invention.

FIG. 6 is a cross sectional detailed view of sight dome 200 with adjustment screw 206 located in the fully open position in an example embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 2 - 6 and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents.

Figure 2 is an exploded view of sight dome 200 in an example embodiment of the invention. Sight dome 200 comprises inner body 202, outer body 204, adjusting screw 206, lower sealing member 208 and upper sealing member 210. In one example embodiment of the invention, sealing members 208 and 210 may be O-rings, but in other example embodiments sealing members 208 and 210 may take other shapes. Sealing members 208 and 210 are made from a resilient material, for example rubber, silicon or the like. Adjusting screw 206 has a threaded end 212 that mates with a threaded inner bore 214 in inner body 202. Adjusting screw 206 has opening 216 , formed into the threaded end 212. In one example embodiment of the invention, both inner body 202 and outer body 204 are made from a transparent material, for example clear plastic. In some example embodiments of the invention, adjusting screw 206 may also be made from a transparent material. In one example embodiment of the invention, the inner body 202, the outer body 204 and the adjustment screw 206 may be injection , molded.

Figure 3 is a cross sectional view of sight dome 200 in an example embodiment of the invention. Inner body 202 is installed inside outer body 204. Sealing members 208 and 210 are installed onto adjusting screw 206. Adjusting screw 206 is threaded into inner body 202. Both the inner body 202 and outer body 204 are generally hollow , shapes with an open ended top and bottom. The open ended top of the inner body forms a bore where the bore has a top end and a threaded main section 214. The top end of the bore has a larger diameter than the main section and at least part of the top end has a tapered surface 338. During operation, a lubricant is forced up through a siphon tube (not shown) into a gap 324 between inner body 202 and outer body 204 and into chamber 326 at the top of inner body 202. Upper sealing member 210 forms the top side of chamber 326 by forming a seal between adjusting screw 206 and outer body 204. When adjusting screw 206 is threaded down into a fully closed position, lower sealing member 208 forms a seal between adjusting screw 206 and inner body 202, thereby sealing the lower side of chamber 326. Using a sealing member fabricated from a resilient material creates a seal that completely stops the flow of lubricant through the sight dome without the requirement of close tolerances between the mating parts. Adjusting screw 206 has an inner bore 320 coupled to opening 216. When adjusting screw is in an open position, lubricant flows through opening 216 into inner bore 320 and then drips down to the bottom of the sight dome where the lubricant is fed into the passing air or fluid stream. Opening 216 is shown shaped as a rectangle, but any other shape may be used and include: circles, squares, triangles, rounded rectangles, ovals and the like. In one example embodiment of the invention, adjusting screw 206 has a socket 322 formed into the top end and is configured to be turned using a tool, for example an Allen wrench. In other example embodiments of the invention, an adjustment knob may be installed or formed onto the end of adjusting screw 206. During operation, adjustment screw 206 can be raised upward with respect to inner and outer body (202 and 204) by un-screwing adjustment screw 206. As adjusting screw 206 is raised, a passageway is opened between adjusting screw 206 and inner body 204, allowing lubricant to flow through sight dome 200 and into the air stream.

Figure 4 is a cross sectional detailed view of sight dome 200 with adjustment screw 206 located in the fully closed position in an example embodiment of the invention. In the fully closed position, lower sealing member 208 contacts and forms a seal against the tapered surface 338. The seal prevents lubricant from flowing through sight dome 200. In one example embodiment of the invention, the top edge of opening

¹ 216, formed in the threaded end 212 of adjusting screw 206, is below the top edge 440 of threaded inner bore 214 when adjustment screw 206 is in the fully closed position.

As adjusting screw 206 is raised, lower sealing member 208 moves upward with respect to tapered surface 338, forming a gap between lower sealing member 208 and tapered surface 338 that allows lubricant to flow past sealing member 208. Figure 5 is a ■ cross sectional detailed view of sight dome 200 with adjustment screw 206 located in a partially open position in an example embodiment of the invention. Tapered surface 338 is shown having a constant slope, but other shapes may be used. For example a bell shaped curve may be used such that the distance between the sealing member 208 and tapered surface 338 increases non-linearly as adjustment screw 206 is moved upward.

In one example embodiment of the invention, when the gap between lower sealing member 208 and the tapered surface 338 first opens, the top surface of opening 216 is below the top edge 440 of threaded bore 214. This causes the lubricant to flow through a torturous path between the threads 212 on the lower end of adjustment screw 206 and the threaded inner bore 214 formed in inner body 202 before entering opening , 216 in adjustment screw 206. Once the lubricant has flowed down the threads and entered opening 216, the lubricant flows into inner bore 320 and then drips down to the bottom of the sight dome where the lubricant is fed into the passing air or fluid stream. In one example embodiment of the invention, the top surface of the opening may remain below the top surface of threaded bore 214 over a range of motion of the adjustment screw, starting from the fully closed position, for example 1/16 turn, 1/8 turn, ¹A turn, 3/8 turn, ¹A turn, ⁷A turn or the like. In other example embodiments of the invention, the amount of rotation of the adjustment screw needed to bring the top surface of the opening above the top surface of threaded bore 214 may be undetermined. In another example embodiment of the invention, the top surface of opening 216 may be above the ' top surface of threaded bore 214 when the gap between lower sealing member 208 and the tapered surface 338 first opens.

Figure 6 is a cross sectional detailed view of sight dome 200 with adjustment screw 206 located in the fully open position in an example embodiment of the invention. In this example embodiment of the invention, the bottom surface of opening 216 is level ¹ with, or above, the top surface 440 of threaded bore 214, allowing the lubricant to flow directly through opening 216 and into inner bore 320. Sealing member 208 has completely cleared the top edge of tapered surface 338 and offers no resistance to the flow of lubricant (shown by arrow 650) through the sight dome. In other example embodiment of the invention, the bottom surface of opening 216 may be below the top

^■ surface 440 of threaded bore 214 in the fully open position and sealing member 208 may still be partially within the bore formed by tapered surface 338.

The flow rate of lubricant through the sight dome of the current invention is controlled using a number of different control features or control zones. The control features or control zones include the space between lower sealing member 208 and the

■ tapered surface 338, the gap between the threads on the threaded end 212 of the adjustment screw 206 and the threaded inner bore in the inner body 202, and the relationship between the top edge of opening 216 and the top edge 440 of threaded inner bore 214. The different control features have a variable affect on the flow rate dependent on the position of the adjustment screw 206 in its adjustment range. For example, the . control zone between lower sealing surface 208 and tapered surface 338 has more of an effect on the lubricant flow rate when the adjustment screw 206 is closer to the fully closed position than when the adjustment screw 206 is near the completely opened position. Once the sealing member is above the top edge of the tapered surface, the effect on the flow rate of lubricant from this control feature is greatly reduced or even , eliminated. The tortuous path between the threads helps control the flow rate when the adjustment screw is near the fully closed position. Once the top surface of opening 216 is above the top surface 440 of threaded inner bore 214, the lubricant can flow directly into opening without traveling along the tortuous path between the threads. This greatly reduces or eliminates the effect that the tortuous path between the threads has on the ^■ flow rate of the lubricant through the sight dome. As the adjustment screw is raised even further and more of opening 216 is above the top surface 440 of threaded inner bore 214, the flow rate is fully dependent on the opening 216 control feature.

Shifting the control of the flow rate between different control features as the adjustment screw 206 moves from the fully closed to the fully open positions allows ■ fine control over the flow rate with a short travel distance of adjustment screw 206. In one example embodiment of the invention, adjustment screw 206 only needs to make two full revolutions between the fully closed position and the completely open position. For finer adjustments in flow rate the thread pitch on adjustment screw 206 can be increased with a corresponding increase in the number of turns required to move from . the fully closed position to the completely open position. In other example embodiments of the invention the adjustment screw may make a different number of turns between the fully closed and the completely open positions, for example 1 turn, 1.5 turns, 1.75 turns, 2.25 turns, 2.5 turns, 3 turns, or the like.

Claims

We claim:

1. A sight dome having a hollow inner body with a top and a bottom where the top and bottom are open ended, characterized by: the open ended top of the inner body forming a bore where the bore has a top end

^■ and a main section and the top end of the bore has a larger diameter than the main section and where the main section is threaded and where at least part of the top end has a tapered surface; an adjustment screw having a top section and a bottom section and where the bottom section is threaded and configured to be screwed down into the threaded main section of the bore in the inner body, from the top of the inner body; an opening formed into the threads in the bottom section of the adjustment screw and coupled to an inner bore formed into a bottom end of the adjustment screw; a lower sealing member attached to the adjustment screw above the threaded bottom section and configured to seal against the tapered surface when the adjustment screw is screwed into a fully closed position, and where a gap is formed between the lower sealing member and the tapered surface when the adjustment screw is unscrewed from the fully closed position thereby allowing a fluid to flow from the top of the inner body, past the lower sealing member, through the opening and into the inner bore.

2. The sight dome of claim 1 where a top edge of the opening is below a top edge of the threaded main section when the adjustment screw is screwed into the fully closed position.

3. The sight dome of claim 1 where a top edge of the opening remains below a top edge of the threaded main section over a range of motion of the adjustment screw and where the range of motion starts at the fully closed position.

4. The sight dome of claim 3 where the range of motion is selected from the group: 1/16 turn, 1/8 turn, VA turn, 3/8 turn, ¹A turn, % turn.

5. The sight dome of claim 1 where a bottom edge of the opening is at least level with a top edge of the threaded main section when the adjustment screw is screwed into a completely opened position.

6. The sight dome of claim 1 where the adjustment screw has a completely opened position and the adjustment screw moves from the fully closed position to the completely open position with a predetermined amount of rotation.

7. The sight dome of claim 6 where the predetermined amount of rotation is selected from the group: 1 turn, 1.5 turns, 1.75 turns, 2 turns, 2.25 turns, 2.5 turns, 3 turns.

8. The sight dome of claim 1 further characterized by: a hollow outer body having a top and a bottom where the top and bottom are open ended and where the inner body is configured to fit inside the outer body forming a gap between the inner body and outer body; an upper sealing member attached to the top section of the adjustment screw above the lower sealing member and configured to form a seal against the hollow outer , body.

9. The sight dome of claim 8 further characterized by: a lubricator, where the bottom of the hollow outer body is attached to the lubricator capturing the inner body and adjustment screw inside the hollow outer body.

10. The sight dome of claim 8 where the inner body, the outer body and the adjustment screw are injection molded.

11. The sight dome of claim 8 where the inner body, the outer body and the adjustment screw are fabricated from plastic.

12. A method of operating a sight dome, characterized by: controlling a flow rate of a lubricant flowing through the sight dome using a first control feature when an adjustment screw is in a first adjustment range; controlling the flow rate of the lubricant using a second control feature when the adjustment screw is in a second adjustment range.

13. The method of operating a sight dome of claim 12 where the first adjustment range partially overlaps with the second adjustment range.

14. The method of operating a sight dome of claim 12 where the first control feature is an interaction between a lower sealing member installed on the adjustment screw and a tapered surface formed in a bore in an inner body, and where the second control feature is a relationship between a top edge of an opening in a threaded end of the adjustment screw and a top edge of a threaded bore in the inner body.

15. The method of operating a sight dome of claim 12 further characterized by: controlling the flow rate of the lubricant using the first control feature and a third control feature when the adjustment screw is in a third adjustment range.

16. The method of operating a sight dome of claim 15 where the third control feature is a torturous path between threads on the adjustment screw and threads in a bore in an inner body.

17. The method of operating a sight dome of claim 15 where the third adjustment range is a subset of the first adjustment range.

18. The method of operating a sight dome of claim 12 where the first control feature completely stops the flow of lubricant through the sight dome when the adjustment screw is at a first end of the first adjustment range.