Five-section type spiral gear for hydraulic equipment

Abstract

The invention relates to the technical field of gears, in particular to a five-section type spiral gear for hydraulic equipment, which comprises a gear, the single tooth profile of the gear sequentially comprises an arc AB, a transition curve BC, an involute CC ', a transition curve B' C 'and an arc A' B 'from the tooth top to the tooth root, and the slope of the transition curve BC is monotonically decreased; each of the transition curve BC and the transition curve B 'C' comprises one of a Bayes curve, a high-order spline interpolation curve and an elliptic curve. Through the arrangement of the arcs AB and the arcs A 'B', the oil trapping problem can be effectively solved, and no extra influence is caused on gear meshing; through the arrangement of a transition curve BC and a transition curve B 'C', the tooth shape design of the gear can be flexibly adjusted according to actual use requirements; the performance of low vibration and low noise is achieved; and meanwhile, the situation that hydraulic equipment collides with one another can be avoided, and the use efficiency of the gear is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of gears, and in particular to a five-section helical gear for hydraulic equipment. Background Art

[0002] Gear pumps, gear flowmeters, etc. are widely used in the hydraulic field. The most widely used gear tooth profile is the involute tooth profile, but this tooth profile will cause oil trapping during use, causing the gears, shafts and bearings to be subjected to large radial forces, which will have a serious impact on their performance. The improved circular arc gears on this basis, such as the spiral circular arc gear rotor and gear pump disclosed in the Chinese patent application number CN202010498194.8, have solved the oil trapping problem, but their design has great limitations.

[0003] Gear design needs to consider design goals such as strength and overlap. When applied to gear pumps, design goals such as displacement and flow fluctuation also need to be considered. For general arc gears, such as a spiral arc gear rotor and a gear pump disclosed in the Chinese patent with application number CN202010498194.8, the center of the arc segment is located on the pitch line. After the gear tooth height coefficient and the involute tooth profile pressure angle are determined, the tooth shape is determined accordingly, and the tooth shape design adjustment space is extremely limited. This makes it difficult for the designed tooth shape to meet different performance indicators at the same time, and it is impossible to obtain higher comprehensive performance. If the center of the arc segment is not on the pitch line, the design adjustment space of the tooth shape increases, which will make it impossible for the tooth top arc and the tooth root arc to mesh at the same time, and will affect the transmission. At the same time, it will also cause collisions and oil trapping between hydraulic equipment, further leading to vibration, noise, and increased flow fluctuations. Summary of the invention

[0004] The present invention aims at the deficiencies in the prior art and provides the following technical solutions:

[0005] A five-segment helical gear for hydraulic equipment comprises a gear, wherein a single tooth profile of the gear comprises an arc AB, a transition curve BC, an involute CC', a transition curve B'C' and an arc A'B' in sequence from the tooth top to the tooth root, wherein the arc AB, the transition curve BC, the transition curve B'C' and the arc A'B' are symmetrically arranged with the center point O of the involute CC' as the symmetry point; the arc AB is tangent to the transition curve BC, the transition curve BC is tangent to the involute CC', the involute CC' is tangent to the transition curve B'C', and the transition curve B'C' is tangent to the arc A'B'; the slope of the transition curve BC decreases monotonically; and the transition curve BC and the transition curve B'C' both comprise one of a Beses curve, a high-order spline interpolation curve and an elliptic curve.

[0006] As an improvement of the above technical solution, the pressure angle range of the involute CC' is within 15-30°.

[0007] As an improvement of the above technical solution, the sum of the gear end face overlap and the axial overlap is greater than 1.

[0008] As an improvement of the above technical solution, the gear axial overlap range is 0.8-1.4.

[0009] As an improvement of the above technical solution, the involute CC' includes an involute OC and an involute OC', and the involute OC and the involute OC' are symmetrically arranged with the center point O as a symmetry point.

[0010] As an improvement of the above technical solution, the involute OC is a straight line segment, and its coordinate equation is:

[0011] y OC =x OC tanα0

[0012] Among them, x OC and OC are the x and y coordinates of the OC segment, and α0 is the pressure angle.

[0013] As an improvement of the above technical solution, the transition curve BC and the transition curve B'C' satisfy the Euler-Savary equation, and the calculation equation thereof is:

[0014]

[0015] Among them, i 12 is the transmission ratio of gear 1 to gear 2, O2P is the distance from the node to the center of gear 2, i 1K and i 2k are the ratio of the instantaneous linear velocities of gear 1 and gear 2 relative to a fixed point K, and O2K is the distance from point K to the center of gear 2.

[0016] As an improvement of the above technical solution, the calculation equation for the gear development is:

[0017]

[0018]

[0019]

[0020] Among them Figure 4 As shown, x and y are the coordinates on the coordinate system OXY, x1 and y1 are the coordinates on the coordinate system O1X1Y1, x2 and y2 are the coordinates on the moving coordinate system O2X2Y2 that is fixed to the gear and is established with the gear rotation center as the origin, b is the distance that a single gear tooth moves, is m k Point curvature radius, α k is mk Point pressure angle, When a single tooth moves a certain distance, the gear rotates at an angle, m k is any point on a single gear tooth, and r2 is the pitch circle radius.

[0021] As an improvement of the above technical solution, the arc AB and the arc A'B' adopt an elliptic curve, and its parameter equation is:

[0022]

[0023] The trajectory equation of its curvature center is:

[0024]

[0025] Among them, x and y are the coordinates of the ellipse curvature, a and b are the lengths of the major and minor semi-axes respectively, and t is the angle parameter.

[0026] Beneficial effects of the present invention:

[0027] The setting of arc AB and arc A'B' can effectively solve the oil trapping problem without causing additional impact on gear meshing; the setting of transition curve BC and transition curve B'C' can flexibly adjust the gear tooth profile design according to actual use requirements; and it has the performance of low vibration and noise; at the same time, it can avoid collisions between hydraulic equipment. When applied to gear pumps, it has high volumetric efficiency and small flow fluctuations, which effectively improves the use efficiency of gears. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the end face tooth profile of a five-segment helical gear of the present invention;

[0029] Figure 2 is a schematic diagram of a five-section spiral gear rack of the present invention;

[0030] Figure 3 is a specific example diagram of a five-segment spiral gear rack of the present invention;

[0031] Figure 4 is the gear rack meshing coordinate system of the present invention;

[0032] Figure 5 It is a schematic diagram of the meshing state of the end faces of the five-segment helical gear of the present invention;

[0033] Figure 6 It is a schematic diagram of the circular arc meshing state of the end face of the five-segment helical gear of the present invention;

[0034] Figure 7 is a schematic diagram of a five-stage helical gear helical gear of the present invention;

[0035] Figure 8is a schematic diagram of the meshing of the five-stage helical gear and the helical gear of the present invention;

[0036] Fig. 9 is an example diagram of the spatial meshing line of the five-segment helical gear and helical gear of the present invention;

[0037] Fig.10 This is a specific example diagram of a five-segment spiral gear rack in which the tooth top and tooth root are elliptical curves of the present invention;

[0038] Fig.11 It is a schematic diagram of the elliptic curve and its star-shaped curvature center trajectory of the present invention;

[0039] Fig.12 This is an example diagram of a five-segment spiral gear rack in which the transition curve of the present invention is a circular arc curve. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] Embodiment 1:

[0042] Please refer to Figure 1-Figure 12 As shown, the present invention provides a five-segment helical gear for hydraulic equipment, comprising a gear, wherein the single tooth profile of the gear comprises an arc AB, a transition curve BC, an involute CC', a transition curve B'C' and an arc A'B' in sequence from the tooth top to the tooth root, and the arc AB, the transition curve BC, the transition curve B'C' and the arc A'B' are symmetrically arranged with the center point O of the involute CC' as the symmetry point;

[0043] The arc AB is tangent to the transition curve BC, the transition curve BC is tangent to the involute CC', the involute CC' is tangent to the transition curve B'C', and the transition curve V'C' is tangent to the arc A'B';

[0044] The slope of the transition curve BC decreases monotonically;

[0045] The transition curve BC and the transition curve B'C' both include one of a Beses curve, a high-order spline interpolation curve and an elliptic curve.

[0046] In this embodiment, the gear is a helical gear. The gear tooth profile includes arc AB, transition curve BC, involute CC', transition curve B'C' and arc A'B' from the tooth top to the tooth root in sequence, adopts a five-segment setting, and is symmetrical with the center point O as the midpoint. The arc AB and the arc A'B' are circular contour curves, which can effectively avoid oil trapping.

[0047] Among them, the tangency between arc AB, transition curve BC, involute CC', transition curve B'C' and arc A'B' satisfies the following equation:

[0048]

[0049]

[0050]

[0051]

[0052] Among them, x AB (B) and y AB (B) are the x and y coordinates of segment AB at point B, x' AB (B) and y' AB (B) are the first-order derivatives of the x and y coordinates of segment AB at point B, and the rest are similar.

[0053] Among them, by satisfying the equation, the tangency between adjacent curves can be guaranteed, thereby ensuring transmission stability and improving gear accuracy and meshing quality.

[0054] Among them, the slope of the transition curve BC decreases monotonically, which means that with the center point O of the intersection of the tooth profile and the pitch line of a single-sided tooth profile as the coordinate origin, the slope of the transition curve BC decreases monotonically from the intersection point C with the involute CC' to the intersection point B with the arc AB, that is:

[0055] f” BC ≤0

[0056] Among them, f” BC The single-sided tooth profile is the derivative of the slope. It represents the contour shape from the tooth top to the tooth root on one side of the gear. The single-sided tooth profile contains different parts such as involute segments, transition curve segments (such as BC) and arc segments (such as AB). It reflects the geometric shape characteristics of the gear on a specific plane, which is of great significance for analyzing the meshing performance, transmission efficiency, strength and other aspects of the gear. Taking the intersection O of the tooth profile and the pitch line of the single-sided tooth profile as the coordinate origin, it is convenient to describe and analyze the position, shape and change law of the transition curve BC on the tooth profile, thereby providing a basis for the design, manufacturing and performance optimization of the gear.

[0057] When the transition curve BC and the transition curve B'C' are Beses curves, they have the following characteristics:

[0058] 1. It has good flexibility and controllability, and the shape of the curve can be changed by adjusting the control points.

[0059] 2. It can achieve smooth transition, and the curve has high continuity at the connection.

[0060] Among them, it can be applied to some high-precision mechanical transmission systems, such as precision instruments, CNC machine tools, etc.

[0061] When the transition curve BC and the transition curve B'C' are high-order spline interpolation curves, they have the following characteristics:

[0062] 1. It can interpolate through a number of given points to generate a smooth curve.

[0063] 2. It has high accuracy and continuity, and can fit complex shapes better.

[0064] Among them, it can be used in engineering applications that require high curve accuracy, such as aerospace, automobile manufacturing and other fields.

[0065] When the transition curve BC and the transition curve B'C' are elliptic curves, they have the following characteristics:

[0066] 1. It has a simple mathematical expression and is relatively easy to calculate.

[0067] 2. It can achieve smoother transitions and has specific geometric properties in some cases.

[0068] 3. The shape is relatively fixed.

[0069] Among them, it is suitable for simple mechanical transmission systems.

[0070] Among them, by setting the transition curve BC and the transition curve B'C', the gear tooth design can be made more flexible and diverse. By adjusting the shape and parameters of the transition curve, different transmission requirements can be met, such as changing the overlap, optimizing the load distribution, etc.; for example, in high-speed transmission, vibration and noise can be reduced by designing a suitable transition curve; in heavy-load transmission, the gear load capacity can be improved by optimizing the transition curve. And it can improve the meshing performance of the arc gear. During the meshing process, the transition curve can make the contact between the tooth surfaces smoother, reduce impact and wear, and at the same time, the transition curve can also adjust the pressure distribution between the tooth surfaces to improve the transmission efficiency and life of the gear. It also has the characteristics of easy processing and manufacturing. Among them, the traditional arc gear processing method may require special tools and equipment, while the transition curve can be realized by a general processing method. For example, CNC processing technology can be used to accurately process the transition curve segment according to the design requirements to improve the processing accuracy and quality of the gear.

[0071] Among them, the setting of arc AB and arc A'B' can effectively solve the oil trapped problem without causing additional impact on gear meshing; the setting of transition curve BC and transition curve B'C' can flexibly adjust the gear tooth profile design according to actual use requirements; and it has the performance of low vibration and noise; at the same time, it can avoid the collision between hydraulic equipment. When applied to gear pumps, the volumetric efficiency is high and the flow fluctuation is small, which effectively improves the use efficiency of the gear.

[0072] The pressure angle of the involute CC' is in the range of 15-30°.

[0073] Among them, the pressure angle range of the involute CC' is within 15-30°, and the preferred range is 20-25°. By setting the pressure angle range within 15-30°, the overall performance balance of the gear can be improved, and a certain balance can be achieved between the load-bearing capacity, overlap and transmission efficiency. A smaller pressure angle (such as 15°) can provide a higher overlap and transmission efficiency, but the load-bearing capacity is relatively low; a larger pressure angle (such as 30°) can improve the load-bearing capacity, but the overlap and transmission efficiency will be reduced. For example, in high-speed and light-load transmission, a smaller pressure angle can be selected to improve the transmission efficiency; and in heavy-load and low-speed transmission, a larger pressure angle can be selected to improve the load-bearing capacity.

[0074] In the preferred range of 20-25°, the load-bearing capacity, overlap and transmission efficiency of the gear can be well balanced, with a certain load-bearing capacity and a high overlap and transmission efficiency.

[0075] The sum of the gear end face overlap and the axial overlap is greater than 1.

[0076] The gear axial overlap ranges from 0.8 to 1.4.

[0077] Among them, the tooth surface of the helical gear is spiral. During the meshing process, the contact line is inclined and longer than the contact line of the spur gear. This increases the end face overlap and axial overlap of the helical gear, thereby increasing the total overlap. Due to the increase in overlap, the helical gear has a larger number of tooth pairs participating in the meshing during the transmission process, making the transmission smoother and reducing impact and vibration.

[0078] Among them, when the total gear overlap is greater than or equal to 1, it means that during the meshing process, there is always at least one pair of gear teeth in contact, ensuring the continuity of transmission; if the total overlap is less than 1, intermittent meshing will occur, resulting in unstable transmission and may even cause impact and noise.

[0079] Among them, the size of the axial overlap is related to the helix angle, number of teeth, module and other parameters of the helical gear. In actual design, by adjusting these parameters, the size of the axial overlap can be controlled. The axial overlap is between 0.8-1.4, which can meet the transmission requirements.

[0080] Among them, the range of 1.0-1.2 in 0.8-1.4 is more preferred. Within this range, the transmission performance of the gear is more ideal, which can ensure sufficient overlap and realize continuous transmission without making the gear structure too complicated. At the same time, the axial overlap within this range is also conducive to improving the gear's load-bearing capacity and transmission stability.

[0081] The involute CC' includes an involute OC and an involute OC', and the involute OC and the involute OC' are symmetrically arranged with the center point O as a symmetry point.

[0082] The involute OC is a straight line segment, and its coordinate equation is:

[0083] y OC =x OC tanα0

[0084] Among them, x OC and OC are the x and y coordinates of the OC segment, and α0 is the pressure angle.

[0085] The transition curve BC and the transition curve B'C' satisfy the Euler-Savary equation, and the calculation equation is:

[0086]

[0087] Among them, i 12 is the transmission ratio of gear 1 to gear 2, O2P is the distance from the node to the center of gear 2, i 1K and i 2k are the ratio of the instantaneous linear velocities of gear 1 and gear 2 relative to a fixed point K, and O2K is the distance from point K to the center of gear 2.

[0088] The calculation equation for the gear development is:

[0089]

[0090]

[0091]

[0092] Among them Figure 4As shown, x and y are the coordinates on the coordinate system OXY, x1 and y1 are the coordinates on the coordinate system O1X1Y1, x2 and y2 are the coordinates on the moving coordinate system O2X2Y2 that is fixed to the gear and is established with the gear rotation center as the origin, b is the distance that a single gear tooth moves, is m k Point radius of curvature, α k is m k Point pressure angle, When a single tooth moves a certain distance, the gear rotates at an angle, m k is any point on a single gear tooth, and r2 is the pitch circle radius.

[0093] like Figure 3 As shown in the figure, a design example of a five-segment helical gear, the arc AB segment height is 0.2m, the transition curve BC segment height is 0.3m, the involute CC' segment is 0.2m, the pitch line height is 0.7m, the full tooth height is 1.4m, the pitch line tooth thickness is πm / 2, the tooth thickness at the tooth root is πm, and m is the gear rack module. In this example, the transition curve BC is obtained by a non-uniform rational spline curve (NURBS curve), and the coordinates of its control points are shown in the following table:

[0094]

[0095]

[0096] Among them, NURBS curves are used to construct transition curves to meet the above requirements. In practical applications, various methods can be used to construct them as long as the gear meshing principle is the same as the above requirements. Figure 5 and Figure 6 The following is a schematic diagram of the meshing state of a gear with 7 teeth. The specific number of teeth can be selected according to specific design requirements.

[0097] in, Figure 7 This is a helical gear designed based on the example tooth shape. Figure 8 Schematic diagram of two helical gears meshing.

[0098] Fig. 9 for Figure 8 The helical gear space meshing curve shown in the figure, 21 is the transition segment meshing line, 22 is the involute meshing line, and 23 is the arc meshing line. The involute segment meshing line is a space straight line segment, the arc segment meshing line is a circular arc on a plane parallel to the end face, and the transition curve segment meshing line is determined according to the specific transition curve tooth profile and is not necessarily the same as the shape shown in the figure.

[0099] in, Fig.12This is a schematic diagram of a five-segment helical gear with an arc transition curve. When an arc curve is used as the transition curve, it is obvious that the center of the transition arc cannot be located on the pitch line, and the center O2 is located on the straight line BO1. The specific position is adjusted according to the design requirements to improve the scope of application.

[0100] Embodiment 2:

[0101] Please refer to Figure 1 , Fig.10 , Fig.11 and Fig.12 As shown, other parts of this embodiment are the same as those of the embodiment 1, and the difference lies in that the arc AB and the arc A'B' segment adopt an elliptical curve.

[0102] The arc AB and the arc A'B' adopt an elliptic curve, and its parametric equation is:

[0103]

[0104] The trajectory equation of its curvature center is:

[0105]

[0106] Among them, x and y are the coordinates of the ellipse curvature, a and b are the lengths of the major and minor semi-axes respectively, and t is the angle parameter.

[0107] Its trajectory is Fig.11 The figure shows a star shape. Based on the principle of gear generating, to ensure smooth meshing, the center of curvature of the elliptical curve above the rack pitch line should be on or below the pitch line. Fig.10 The major axis of the median ellipse is on the nodal line, and the corresponding center of curvature is below the nodal line. Fig.12 State diagram comparison.

[0108] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them.

Claims

1. A five-stage helical gear for hydraulic equipment, comprising a gear, characterized in that: The single tooth profile of the gear includes arc AB, transition curve BC, involute CC', transition curve B'C' and arc A'B' in sequence from tooth top to tooth root, and the arc AB, transition curve BC, transition curve B'C' and arc A'B' are symmetrically arranged with the center point O of involute CC' as the symmetry point; The arc AB is tangent to the transition curve BC, the transition curve BC is tangent to the involute CC', the involute CC' is tangent to the transition curve B'C', and the transition curve B'C' is tangent to the arc A'B'; The slope of the transition curve BC decreases monotonically; The transition curve BC and the transition curve B′C′ both include one of a Beses curve, a high-order spline interpolation curve and an elliptic curve.

2. The five-stage helical gear for hydraulic equipment according to claim 1, characterized in that: The pressure angle of the involute CC' is in the range of 15-30 degrees.

3. The five-stage helical gear for hydraulic equipment according to claim 1, characterized in that: The sum of the gear end face overlap and the axial overlap is greater than 1.

4. The five-stage helical gear for hydraulic equipment according to claim 3, characterized in that: The gear axial overlap ranges from 0.8 to 1.

4.

5. The five-stage helical gear for hydraulic equipment according to claim 1, characterized in that: The involute CC′ includes an involute OC and an involute OC′, and the involute OC and the involute OC′ are symmetrically arranged with the center point O as a symmetry point.

6. The five-stage helical gear for hydraulic equipment according to claim 5, characterized in that: The involute OC is a straight line segment, and its coordinate equation is: yO c =x OC ·tanα0 Among them, x OC and OC are the x and y coordinates of the OC segment, and α0 is the pressure angle.

7. The five-stage helical gear for hydraulic equipment according to claim 1, characterized in that: The transition curve BC and the transition curve B′C′ satisfy the Euler-Savary equation, and the calculation equation is: Among them, i 12 is the transmission ratio of gear 1 to gear 2, O2P is the distance from the node to the center of gear 2, i 1K and i 2k are the ratio of the instantaneous linear velocities of gear 1 and gear 2 relative to a fixed point K, and O2K is the distance from point K to the center of gear 2.

8. The five-stage helical gear for hydraulic equipment according to claim 1, characterized in that: The calculation equation for the gear development is: As shown in Figure 4, x and y are coordinates on the coordinate system OXY, x1 and y1 are coordinates on the coordinate system O1X1Y1, x2 and y2 are coordinates on the moving coordinate system O2X2Y2 that is fixed to the gear and is established with the gear rotation center as the origin, and b is the distance that a single gear tooth moves. is m k Point radius of curvature, α k is m k Point pressure angle, When a single tooth moves a certain distance, the gear rotates at an angle, m k is any point on a single gear tooth, and r2 is the pitch circle radius.

9. The five-stage helical gear for hydraulic equipment according to claim 1, characterized in that: The arc AB and the arc A'B' adopt elliptic curves, and their parametric equations are: The trajectory equation of its curvature center is: Among them, x and y are the coordinates of the ellipse curvature, a and b are the lengths of the major and minor semi-axes respectively, and t is the angle parameter.

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