Anti-unscrewing device for crank pin assembly of oil pumping unit

Abstract

The invention discloses an anti-unscrewing device for a crank pin assembly of an oil pumping unit, which comprises a crank pin, the crank pin is provided with a free end, a first section and a second section are sequentially formed on the crank pin along the direction far away from the free end, and external threads in opposite directions are arranged on the outer side walls of the first section and the second section; the external threads of the second section are in threaded fit with internal threads of a crown-shaped nut arranged on the outer side of the second section in a sleeving mode, the external threads of the first section are in threaded fit with internal threads of a standby nut arranged on the outer side of the first section in a sleeving mode, and the bottom end face, facing the crown-shaped nut, of the standby nut abuts against the top end face, facing the standby nut, of the crown-shaped nut. When the crank pin is used, the crown-shaped nut is tightened firstly, then the standby nut is tightened, when the crown-shaped nut is unscrewed, the reversely-buckled standby nut rotates synchronously with the crown-shaped nut, the standby nut abuts against the crown-shaped nut, the standby nut rotates more and more tightly, and therefore the function of preventing the crank pin from being unscrewed is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of an anti-backlash device for a crank pin of an oil pumping unit, and in particular to an anti-backlash device for a crank pin assembly of an oil pumping unit. Background Art

[0002] The method used by the Northwest Oilfield Branch to prevent the crank pin of the 14-type and 16-type beam pumping units from buckling is to fix them with baffle bolts. The more common pumping unit accidents are mostly caused by the loosening of the crown nut, which eventually causes the crank pin to come out. In the lightest case, the single arm is damaged and the beam is damaged. In the worst case, the pumping unit flips over. In the most serious case, the wellhead is damaged, causing a well control incident. It is common to draw a safety line (the crown nut and the pin end face are in the shape of a "one"), and observe whether the safety line is flush and without misalignment during inspections. If necessary, stop the machine for inspection. In recent years, there have been frequent incidents in our region where the crank pin bearing baffle fixing bolts are broken, causing the crank pin bearing to escape.

[0003] The crank pin is a key connecting component of the pumping unit, and it is also a weak link. The transmission connection between the crank and the connecting rod is completed by the crank pin assembly. The crank pin assembly is fixed to the crank by the crown nut and the spare cap (baffle). Since the pumping unit is subjected to a large alternating load, the crown nut and the spare cap (baffle) as the parts bearing the alternating load are prone to buckling. In field applications, since the thread directions of the crown nut and the spare cap are consistent, once the crown nut is loose and buckled, the spare cap and the crown nut are bound to buckle at the same time under the action of the circumferential force, eventually causing the crank pin to come out, resulting in deformation of the connecting rod, damage to the tail shaft and the middle shaft, and in severe cases, causing the pumping unit to flip, smashing the oil wellhead equipment, causing oil and gas leakage and pollution, and endangering the personal safety of the operator.

[0004] Therefore, how to provide a pumping unit crank pin assembly anti-backoff device that can avoid the above-mentioned disadvantages becomes an urgent problem that needs to be solved. Summary of the invention

[0005] The technical problem to be solved by the present invention is to develop a "device to prevent the crank pin assembly of a pumping unit from buckling out and the bearing from slipping out" in response to the causes of the crank pin buckling out and the bearing from slipping out, and to avoid the single arm damage and crossbeam damage caused by the crank pin buckling out and the bearing from slipping out, and even the pumping unit tipping over, damaging the oil wellhead equipment and other well control hazards and safety hazards. The specific technical solution is as follows:

[0006] A device for preventing the back-off of a crank pin assembly of an oil pump comprises a crank pin having a free end. The crank pin is sequentially formed with a first section and a second section in a direction away from the free end. The outer walls of the first section and the second section are provided with external threads with threads in opposite directions. The external threads of the second section are threadedly matched with the internal threads of a crown nut sleeved on the outer side of the second section. The external threads of the first section are matched with the internal threads of a spare nut sleeved on the outer side of the first section. The bottom end surface of the spare nut facing the crown nut abuts against the top end surface of the crown nut facing the spare nut.

[0007] Preferably, the end of the first section away from the second section is the free end.

[0008] Preferably, a plug-in hole is provided on the crank pin, which extends along the axial direction of the crank pin and passes through the free end. The plug-in hole is provided with an internal plug-in thread, and also includes screws of the same number as the plug-in holes, each screw is provided with an external plug-in thread matching the internal plug-in thread, the free end of each screw is plugged into the plug-in hole, and a screw head limiting structure is provided at the position of the screw head at the top of each screw corresponding to the spare nut.

[0009] Preferably, the spare nut includes a small-diameter threaded section and a large-diameter cavity section connected to each other, the chamber of the small-diameter threaded section is connected to the chamber of the large-diameter cavity section, the small-diameter threaded section is close to the crown-shaped nut and the inner thread of the spare nut is arranged on the inner side thereof, the inner diameter of the large-diameter cavity section is larger than the inner diameter of the small-diameter thread, a first inner step is formed at the intersection of the two, and a pad is also included, which is abutted against the first inner step, the pad forms the screw head limiting structure, and a number of through holes equal to the number of the screw are opened on the pad.

[0010] Preferably, the pad has three through holes, which are respectively located at three vertices of a triangle.

[0011] Preferably, the diameter of the first section is smaller than the diameter of the second section.

[0012] Preferably, the crown nut is concave on one side toward the spare nut to form a concave chamber, the inner diameter of the concave chamber is larger than the inner diameter of the crown nut where its internal thread is set, and a second inner step is formed at the intersection of the two, and the bottom end face of the spare nut abuts against the second inner step.

[0013] The technical effects of the device provided are:

[0014] When in use, tighten the crown nut first and then the backup nut. When the crown nut is buckled, the reversed backup nut will rotate synchronously with it, and the backup nut will rotate tighter and tighter against the crown nut, thereby preventing the crank pin from buckling. It can prevent the crank pin from buckling, thereby avoiding the bearing from running out, effectively avoiding the risk of rollover, and ensuring the safe and stable operation of the pumping unit. While ensuring the safe and stable production of the oil well, it maximizes the service life of the equipment. From the previous passive human defense to active machine defense, it completely eliminates safety hazards from the source and avoids the accident of the pumping unit flipping over; avoids the occurrence of well control events and large-scale environmental pollution caused by the pumping unit rolling over and injuring the wellhead, causing damage to the wellhead equipment; ensures the safe and stable operation of the oil well, improves the production timeliness; extends the service life of the pumping unit and saves production costs.

[0015] Preferably, a plug hole and a screw rod are provided to further strengthen the strength of the nut coupled to the crank pin.

[0016] Preferably, the diameter of the first section is limited to be smaller than the diameter of the second section, so that the thickness of the spare nut can be increased as much as possible within a limited space, thereby increasing its strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention is a schematic structural diagram of a specific implementation of the anti-backoff device for the crank pin assembly of an oil pumping unit provided by the present invention.

[0018] Figure 1 The accompanying drawings are denoted as follows:

[0019] 1 crank, 2 crank pin, 3 first section, 4 second section, 5 crown nut, 6 spare nut, 7 screw rod, 8 small diameter thread section, 9 large diameter cavity section, 10 pad, 11 second inner step. DETAILED DESCRIPTION

[0020] The present invention will be described in further detail below.

[0021] The present invention will be described in more detail below with reference to the accompanying drawings, in which preferred embodiments of the present invention are shown, and it should be understood that those skilled in the art can modify the present invention described herein and still achieve the beneficial effects of the present invention. Therefore, the following description should be understood as being widely known to those skilled in the art, and not as a limitation of the present invention.

[0022] For the sake of clarity, not all features of the actual embodiments are described. In the following description, well-known functions and structures are not described in detail because they would obscure the present invention with unnecessary details. It should be recognized that in the development of any actual embodiment, a large number of implementation details must be made to achieve the specific goals of the developer.

[0023] In order to make the purpose and features of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise ratios, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0024] Combination Figure 1 , which is a structural schematic diagram of a specific implementation of the anti-backoff device of the crank pin assembly of the oil pump provided by the present invention.

[0025] In a specific implementation manner, Figure 1 As shown, a pumping unit crank pin assembly anti-backoff device includes a crank pin 2 connected to a crank 1, which has a free end. The crank pin 2 is sequentially formed with a first section 3 and a second section 4 in a direction away from the free end. The outer walls of the first section 3 and the second section 4 are provided with external threads with threads in opposite directions. The external threads of the second section 4 are matched with the internal threads of a crown nut 5 sleeved on the outer side of the second section 4. The external threads of the first section 3 are matched with the internal threads of a spare nut 6 sleeved on the outer side of the first section 3. The bottom end face of the spare nut 6 facing the crown nut 5 abuts against the top end face of the crown nut 5 facing the spare nut 6.

[0026] When in use, tighten the crown nut 5 first and then tighten the spare nut 6. When the crown nut 5 is unfastened, the reversed spare nut 6 will rotate synchronously with it, and the spare nut 6 will rotate tighter and tighter against the crown nut 5, thereby preventing the crank pin 2 from being unfastened. It can prevent the crank pin 2 from being unfastened, thereby avoiding the bearing from running out, effectively avoiding the risk of rollover, and ensuring the safe and stable operation of the pumping unit. While ensuring the safe and stable production of the oil well, the service life of the equipment is extended to the maximum. From the previous passive human defense to active machine defense, the safety hazards are completely eliminated from the source, avoiding the accident of the pumping unit turning over; avoiding the occurrence of well control events and large-scale environmental pollution well control accidents caused by the pumping unit rolling over and injuring the wellhead, causing damage to the wellhead equipment; ensuring the safe and stable operation of the oil well, improving the production time efficiency; extending the service life of the pumping unit, and saving production costs.

[0027] In a specific implementation manner, Figure 1 As shown, the end of the first section 3 away from the second section 4 is the free end.

[0028] Furthermore, a plug-in hole is provided on the crank pin 2, which extends along the axial direction of the crank pin 2 and penetrates to the free end. The plug-in hole is provided with an internal plug-in thread, and also includes screws 7 of the same number as the plug-in holes. Each screw 7 is provided with an external plug-in thread matching the internal plug-in thread. The free end of each of the screws 7 is plugged into the plug-in hole, and a screw head limiting structure is provided at the position of the screw head at the top of each screw 7 corresponding to the spare nut 6.

[0029] The insertion hole and the screw rod 7 are provided to further strengthen the strength of the nut 6 being coupled to the crank pin 2 .

[0030] like Figure 1 As shown, in a specific embodiment, the spare nut 6 includes a small diameter threaded section 8 and a large diameter cavity section 9 connected to each other, the chamber of the small diameter threaded section 8 is connected to the chamber of the large diameter cavity section 9, the small diameter threaded section 8 is close to the crown nut 5 and the inner side of the spare nut 6 is provided with an internal thread, the inner diameter of the large diameter cavity section 9 is larger than the inner diameter of the small diameter thread 8, and a first inner step is formed at the intersection of the two, and also includes a pad 10, which is abutted against the first inner step, and the pad 10 forms the screw head limiting structure, and a number of through holes equal to the number of the screw 7 are opened on the pad 10.

[0031] There are three through holes on the pad 10 , and the three through holes are respectively located at three vertices of a triangle.

[0032] In a specific implementation manner, the diameter of the first section 3 is smaller than the diameter of the second section 4 .

[0033] By limiting the diameter of the first section 3 to be smaller than the diameter of the second section 4, the thickness of the spare nut 6 can be increased as much as possible within a limited space, thereby increasing its strength.

[0034] like Figure 1 As shown, in a specific embodiment, the crown nut 5 is concave on one side toward the spare nut 6 to form a concave chamber, the inner diameter of the concave chamber is larger than the inner diameter of the crown nut 5 where its internal thread is set, and a second inner step 11 is formed at the intersection of the two, and the bottom end surface of the spare nut 6 abuts against the second inner step 11.

[0035] The above shows and describes the basic principles, main features and advantages of the present invention, so the above is only an embodiment of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the above embodiments, and the above embodiments and descriptions only describe the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention also includes various equivalent changes and improvements, which will fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A pumping unit crank pin assembly anti-backlash device, characterized in that: It includes a crank pin, which has a free end. The crank pin is sequentially formed with a first section and a second section in a direction away from the free end. The outer walls of the first section and the second section are provided with external threads with threads in opposite directions. The external threads of the second section are matched with the internal threads of a crown nut arranged on the outer side of the second section. The external threads of the first section are matched with the internal threads of a spare nut arranged on the outer side of the first section. The bottom end surface of the spare nut facing the crown nut abuts against the top end surface of the crown nut facing the spare nut.

2. The anti-backlash device for the crank pin assembly of the oil pumping unit according to claim 1 is characterized in that: An end of the first section away from the second section is the free end.

3. The anti-backlash device for the crank pin assembly of the oil pumping unit according to claim 2 is characterized in that: The crank pin is provided with a plug-in hole, which extends along the axial direction of the crank pin and penetrates to the free end. The plug-in hole is provided with an internal plug-in thread, and also includes screws of the same number as the plug-in holes, each screw is provided with an external plug-in thread matching the internal plug-in thread, and the free end of each screw is plugged into the plug-in hole, and the spare nut is provided with a screw head limiting structure at the position of the screw head corresponding to the top end of each screw.

4. The anti-backlash device for the crank pin assembly of the oil pumping unit according to claim 3 is characterized in that: The spare nut includes a small-diameter threaded section and a large-diameter cavity section connected to each other. The chamber of the small-diameter threaded section is connected to the chamber of the large-diameter cavity section. The small-diameter threaded section is close to the crown-shaped nut and the inner thread of the spare nut is arranged on the inner side. The inner diameter of the large-diameter cavity section is larger than the inner diameter of the small-diameter thread. A first inner step is formed at the intersection of the two. The spare nut also includes a pad, which is abutted against the first inner step. The pad forms the screw head limiting structure, and a number of through holes equal to the number of the screw are opened on the pad.

5. The anti-backlash device for the crank pin assembly of the oil pumping unit according to claim 4, characterized in that: The number of through holes formed on the pad is three, and the three through holes are respectively located at three vertices of a triangle.

6. The anti-backlash device for the crank pin assembly of the oil pumping unit according to claim 5, characterized in that: The diameter of the first section is smaller than the diameter of the second section.

7. The anti-backlash device for the crank pin assembly of the oil pumping unit according to claim 6, characterized in that: The crown nut is concave on one side toward the backup nut to form a concave chamber, the inner diameter of the concave chamber is larger than the inner diameter of the crown nut where its internal thread is set, and a second inner step is formed at the intersection of the two, and the bottom end surface of the backup nut abuts against the second inner step.

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