Universal joint with high repeat positioning accuracy and engineering surveying instrument using the same

Abstract

The application relates to a universal joint with high repeated positioning accuracy and an engineering measuring instrument applying the same. The universal joint comprises an upper yoke and a lower yoke connected with each other through a cross shaft. The cross shaft comprises a center block. A through hole is formed in the left side of the center block. A first bearing is fixedly matched in the through hole. A first annular raceway and a second annular raceway are respectively formed on the outer side of the inner ring of the first bearing and the inner side of the outer ring of the first bearing. The cross sections of the first annular raceway and the second annular raceway are V-shaped. The balls of the first bearing are arranged between the first annular raceway and the second annular raceway. A first shaft is arranged in the inner ring of the first bearing. The lower yoke comprises two first yoke ears arranged at intervals. The first shaft is arranged between the two first yoke ears. The engineering measuring instrument applying the universal joint has the characteristics of high repeated positioning accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to a universal joint for engineering surveying instruments and an engineering surveying instrument using the same. BACKGROUND

[0002] As Figures 4-5 , the prior art universal joint for engineering surveying instruments (including laser leveling instruments, total station positioning instruments, range finders, theodolites, levels, automatic leveling instruments, mapping instruments, laser measuring instruments, projectors, photographic instruments, etc.) comprises an upper yoke 29 and a lower yoke 30 connected to each other by a cross shaft 28, the upper yoke 29 is adapted to be rotatably arranged on a base of the engineering surveying instrument, the lower yoke 30 is adapted to be fixedly connected with a laser assembly, the cross shaft 28 comprises a first shaft 31 and a second shaft 32 arranged perpendicularly to each other, the lower yoke 30 comprises two spaced apart yoke ears 33, mounting holes 34 are formed in the yoke ears 33, bearings 35 for supporting rotation of the second shaft 32 are fixedly fitted in the mounting holes 34; the rotation accuracy of the bearings 35 will directly affect the positioning accuracy of the engineering surveying instrument.

[0003] The prior art universal joint has the following problems: since the bearings 35 necessarily have radial play, the existence of the radial play will cause the lower yoke 30 to displace along the axial direction of the second shaft 32 (i.e. axial play) and produce a center of gravity offset, the lower yoke 30 will affect the positioning accuracy of the engineering surveying instrument after the center of gravity offset, the positioning accuracy of the same engineering surveying instrument is often not the same each time, and the repeated positioning accuracy is poor; in order to ensure that the engineering surveying instrument can obtain good positioning accuracy, the bearings with small axial play are usually manually selected by using a tool and assembled on the lower yoke 30, this method cannot fundamentally solve the problem and cannot achieve the expected effect. SUMMARY

[0004] The technical problem solved by the present application is to provide a universal joint with high repeated positioning accuracy and an engineering surveying instrument using the same, the engineering surveying instrument using the universal joint of the present application has the characteristic of high repeated positioning accuracy.

[0005] To solve the above technical problem, the present application provides a universal joint with high repeated positioning accuracy, comprising an upper yoke and a lower yoke connected to each other by a cross shaft, the cross shaft comprises a center block, a through hole is formed in the left side of the center block, a first bearing is fixedly fitted in the through hole, first and second annular raceways are respectively formed on the outer side of the inner ring of the first bearing and the inner side of the outer ring of the first bearing, the cross sections of the first and second annular raceways are V-shaped, the rolling balls of the first bearing are arranged between the first and second annular raceways, a first shaft is arranged in the inner ring of the first bearing, the lower yoke comprises two spaced apart first yoke ears, and the first shaft is arranged between the two first yoke ears.

[0006] Further, the front and rear sides of the center block are respectively provided with counterbores, and the counterbores are matched with second bearings; the upper yoke comprises two second yoke ears arranged at intervals, and second shafts are arranged through the second yoke ears; the inner ends of the two second shafts are respectively supported to rotate by the front and rear second bearings.

[0007] Further, the cross sections of the first and second annular raceways are respectively in the shape of isosceles trapezoids without a bottom side, and the included angle between the two inclined sides of the isosceles trapezoid without a bottom side is 115°-125°; the axial play of the first bearing of the structure is small, and the structure is more stable.

[0008] Further, the left end of the through hole is internally screwed with a locking nut, the right end of the through hole is internally provided with a limiting ring, and the outer ring of the first bearing is located between the locking nut and the limiting ring; the locking nut and the limiting ring realize axial fixation of the outer ring of the first bearing.

[0009] Further, the first shaft comprises a left half shaft and a right half shaft, the right half shaft comprises a supporting section, the left end of the supporting section is provided with a connecting section, the diameter of the connecting section is smaller than that of the supporting section, the right end of the left half shaft is provided with a first threaded hole, and the left end of the connecting section passes through the inner ring and is screwed in the first threaded hole; the first shaft and the inner ring are relatively fixed and have no axial play.

[0010] Further, the first yoke is provided with supporting holes matched with the two ends of the first shaft, the first yoke is provided with a second threaded hole communicating with the supporting holes, a stud screw is screwed in the second threaded hole, and the inner end of the stud screw abuts against one end of the corresponding first shaft; the first shaft and the lower yoke are relatively fixed and have no axial play.

[0011] An engineering surveying instrument, wherein the base is arranged on the upper yoke of the universal joint.

[0012] The beneficial effects of the present application are as follows: since the lower yoke and the first shaft are relatively fixed, the axial play of the first bearing will directly affect the positioning accuracy of the engineering surveying instrument, the cross sections of the first and second annular raceways are both in the shape of V, the balls of the first bearing are arranged between the first and second annular raceways, and thus the axial play of the first bearing is very small, and the repeated positioning accuracy of the engineering surveying instrument using the universal joint is guaranteed; the engineering surveying instrument using the universal joint of the present application has the characteristic of high repeated positioning accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to clearly illustrate the innovative principles of the application and the advantages thereof compared with the prior art, possible embodiments will be described below by means of non-limiting examples with reference to the accompanying drawings. In the drawings:

[0014] Figure 1 a cross-sectional view of the joint of the present application;

[0015] Figure 2 a cross-sectional view on the center line of Figure 1

[0016] Figure 3 a cross-sectional view of the first bearing;

[0017] Figure 4 a cross-sectional view of the joint of the prior art;

[0018] Figure 5 a cross-sectional view on the center line of Figure 4 DETAILED DESCRIPTION

[0019] The technical solutions of the present application will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments.

[0020] Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor under the premise that the embodiments in the present application belong to the scope of protection of the present application.

[0021] It should be noted that all directional indications, such as upper, lower, left, right, front, back, etc., in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly.

[0022] In the present application, unless otherwise explicitly specified and limited, the terms "connection", "fixation", etc. should be understood broadly, for example, "fixation" can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be direct connection, or indirect connection through an intermediate medium; can be internal connection of two elements or interaction relationship between two elements, unless otherwise explicitly limited. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0023] Embodiment 1

[0024] As Figures 1-3 ​​The universal joint of the embodiment comprises an upper yoke 2 and a lower yoke 3 connected with each other through a cross shaft, the cross shaft comprises a center block 4, a through hole 5 is formed in the left side of the center block 4, a first bearing 6 is fixedly fitted in the through hole 5, a first annular raceway 1 and a second annular raceway 7 are respectively formed in the outer side of an inner ring 10 of the first bearing 6 and the inner side of an outer ring 11 of the first bearing 6, the cross sections of the first annular raceway 1 and the second annular raceway 7 are both V-shaped, a plurality of rolling balls 12 of the first bearing 6 are arranged between the first annular raceway 1 and the second annular raceway 7, a first shaft 8 is arranged in the inner ring 10 of the first bearing 6, the lower yoke 3 comprises two first yoke ears 9 arranged at intervals, and the first shaft 8 is arranged between the two first yoke ears 9.

[0025] Preferably, a counterbore 13 is formed in the front side and the rear side of the center block 4 respectively, a second bearing 14 is fitted in the counterbores 13, the upper yoke 2 comprises two second yoke ears 15 arranged at intervals, a second shaft 16 is arranged through the second yoke ears 15, and the inner ends of the two second shafts 16 are respectively supported to rotate through the front and rear second bearings 14.

[0026] Preferably, the cross sections of the first annular raceway 1 and the second annular raceway 7 are both isosceles trapezoids without a bottom side, and the included angle B between the two inclined sides of the isosceles trapezoid without a bottom side is 120°; the axial play of the first bearing with the structure is small, and the structure is more stable.

[0027] A locking nut 17 is threadedly fitted in the left end port of the through hole 5, a limiting ring 18 is arranged in the right end port of the through hole 5, and the outer ring 11 of the first bearing 6 is located between the locking nut 17 and the limiting ring 18; the locking nut and the limiting ring realize the axial fixation of the outer ring of the first bearing.

[0028] The first shaft 8 comprises a left half shaft 19 and a right half shaft 20, the right half shaft 20 comprises a supporting section 21, a connecting section 23 is arranged at the left end of the supporting section 21, the diameter of the connecting section 23 is smaller than the diameter of the supporting section 21, a first threaded hole 24 is formed in the right end of the left half shaft 19, and the left end of the connecting section 23 passes through the inner ring 10 and is threadedly fitted in the first threaded hole 24; the first shaft and the inner ring are relatively fixed, and there is no axial play.

[0029] A supporting hole 25 is formed in the first yoke ear 9, the two supporting holes 25 are respectively fitted with the two ends of the first shaft 8, a second threaded hole 26 is formed in the first yoke ear 9 and communicates with the supporting hole 25, a stud bolt 27 is threadedly fitted in the second threaded hole 26, and the inner end of the stud bolt 27 abuts against one end of the corresponding first shaft 8; the first shaft and the lower yoke are relatively fixed, and there is no axial play.

[0030] Embodiment 2

[0031] An engineering surveying instrument, the base of which is arranged on the upper yoke 2 of the gimbal described in Embodiment 1.

[0032] Since the lower yoke 3 is relatively fixed with the first shaft 8, the rotation accuracy of the first bearing 8 will directly affect the positioning accuracy of the engineering surveying instrument, the cross sections of the first and second annular raceways 1, 7 are V-shaped, the balls 12 of the first bearing 6 are arranged between the first and second annular raceways 1, 7, thus the axial play of the first bearing 6 is very small, the repeated positioning accuracy of the engineering surveying instrument (including: laser leveling instrument, total station positioning instrument, range finder, theodolite, level, automatic leveling instrument, mapping instrument, laser measuring instrument, projector, photographic instrument, etc.) using the gimbal is guaranteed; the engineering surveying instrument using the gimbal of the embodiment has the characteristic of high repeated positioning accuracy.

[0033] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, can make several improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A universal joint comprising an upper yoke (2) and a lower yoke (3) connected to each other by a cross pin, characterized in that: The cross shaft comprises a center block (4), a through hole (5) is formed in the left side of the center block (4), a first bearing (6) is fixedly connected in the through hole (5), a first annular raceway (1) and a second annular raceway (7) are respectively formed in the outer side of an inner ring (10) of the first bearing (6) and the inner side of an outer ring (11) of the first bearing (6), the cross sections of the first annular raceway (1) and the second annular raceway (7) are V-shaped, the first bearing (6) is provided with a first shaft (8) in the inner ring (10), the lower yoke (3) comprises two first yoke ears (9) which are spaced apart, and the first shaft (8) is arranged between the two first yoke ears (9). The first shaft (8) comprises a left half shaft (19) and a right half shaft (20), the right half shaft (20) comprises a supporting section (21), the left end of the supporting section (21) is provided with a connecting section (23), the diameter of the connecting section (23) is smaller than the diameter of the supporting section (21), the right end of the left half shaft (19) is provided with a first threaded hole (24), and the left end of the connecting section (23) penetrates through the inner ring (10) and is threadedly connected in the first threaded hole (24). A supporting hole (25) is formed in the first yoke ear (9), the two supporting holes (25) are respectively matched with the two ends of the first shaft (8), a second threaded hole (26) which is in communication with the supporting hole (25) is formed in the first yoke ear (9), a head screw (27) is threadedly connected in the second threaded hole (26), and the inner end of the head screw (27) abuts against one end of the corresponding first shaft (8). A locking nut (17) is threadedly connected in the left end of the through hole (5), a limiting ring (18) is arranged in the right end of the through hole (5), and the outer ring (11) of the first bearing (6) is located between the locking nut (17) and the limiting ring (18).

2. The universal joint of claim 1, wherein: Front and rear sides of the center block (4) are respectively provided with counterbores (13), the counterbores (13) are matched with second bearings (14), the upper yoke (2) comprises two second yoke ears (15) which are spaced apart, second shafts (16) are arranged in the second yoke ears (15), and the inner ends of the two second shafts (16) are respectively supported to rotate through the front and rear second bearings (14).

3. The universal joint of claim 1, wherein: The cross sections of the first and second annular raceways (1, 7) are respectively isosceles trapezoids without bottom sides, and the included angle (B) between the two inclined sides of the isosceles trapezoid without bottom side is 115°-125°.

4. An engineering surveying instrument characterised in that: The base of the engineering surveying instrument is arranged on the upper yoke (2) of the universal joint in claim 1.

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