A double arc gear pump

Abstract

The present invention relates to a double circular arc gear pump, wherein a driving double circular arc gear and a driven double circular arc gear of instantaneous single-point meshing transmission are arranged in a pump body; the driving double circular arc gear and the driven double circular arc gear are both line gears provided with a plurality of line teeth; the line teeth are provided with tooth tops, transition curved surfaces and tooth roots connected in sequence; the tooth tops and tooth roots are conjugated circular arc tooth shapes; the transition curved surface is tangent to the tooth roots; the transition curved surface is provided with a contact line composed of a plurality of instantaneous meshing points; the contact line is a cylindrical spiral line; the pitch circle radius of the line gear is equal to the meshing radius of the contact line. The circular arc main gear and the circular arc secondary gear have only one contact point on the end face where the instantaneous meshing point is located, and the two gears are in a disengaged state on the other end faces, so that no closed oil trapped volume is formed, thereby avoiding the oil trapped phenomenon in the gear pump, avoiding the phenomenon of the instantaneous meshing line constantly changing, ensuring the constant radial leakage at the gear meshing point during the meshing process, and improving the stability of the output flow of the gear pump.

Description

Technical Field

[0001] The invention relates to the technical field of fluid machinery, in particular to a double circular arc gear pump. Background Art

[0002] External gear pumps are widely used in fluid transmission, automation and aerospace fields. The most widely used tooth profile is the involute tooth profile, but this tooth profile will cause oil entrapment during the transmission process, causing the gears, shafts and bearings to be subjected to large radial forces, and will also have a serious impact on the dynamic performance of the gear pump, such as the output flow and output pressure.

[0003] The conventional method to alleviate the oil trapped phenomenon is to open different forms of pressure relief grooves or pressure relief holes, but it cannot fundamentally eliminate the oil trapped phenomenon of the gear pump and will also increase the difficulty of manufacturing the gear pump.

[0004] The prior art discloses a gear pump using spiral arc gears, wherein an arc main gear is installed in a pump body, seat rings 1 are provided on both sides of the arc main gear, a sliding bearing is installed between the seat ring 1 and the arc main gear shaft, a skeleton oil seal and a hole elastic retaining ring are installed at the connection between the left end of the arc main gear and the front cover, and a balance piston 1 is installed at the connection between the right end and the rear cover; an arc sub-gear is meshed and connected with the arc main gear, seat rings 2 are provided on both sides of the arc sub-gear, a sliding bearing is installed between the seat ring 2 and the arc sub-gear shaft, and a balance piston 2 is installed at the connection between the right end of the arc sub-gear and the rear cover, and the pump body is positioned with positioning pins on the front cover and the rear cover.

[0005] There are the following technical problems: in the process of a pair of gear teeth entering into meshing and exiting meshing, the length of their instantaneous meshing line will inevitably first become longer and then shorten, causing the radial leakage at the gear meshing point to first become smaller and then larger, thereby causing the output flow of the gear pump to fluctuate, which is not conducive to the application of gear pumps in occasions such as aerospace engine hydraulic systems that require low output flow pulsation. Summary of the invention

[0006] In view of the technical problems existing in the prior art, the purpose of the present invention is to provide a double circular arc gear pump, in which oil trapping will not occur during the transmission process, the radial leakage at the gear meshing point is constant and controllable, the output flow fluctuation is small, and there is no wear on the tooth surface during the gear pair meshing process.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A double circular arc gear pump, wherein a driving double circular arc gear and a driven double circular arc gear of instantaneous single point meshing transmission are arranged in the pump body;

[0009] Both the active double circular arc gear and the driven double circular arc gear are linear gears provided with a plurality of linear teeth;

[0010] The line teeth are provided with tooth tops, transition curved surfaces and tooth roots connected in sequence;

[0011] The tooth top and tooth root are conjugate arc tooth shapes;

[0012] The transition surface is tangent to the tooth root;

[0013] The transition surface is provided with a contact line consisting of a plurality of instantaneous meshing points;

[0014] The contact line is a cylindrical helix;

[0015] The pitch radius of the line gear is equal to the meshing radius of the contact line.

[0016] The pump has the advantages of no oil entrapment, constant and controllable radial leakage at the gear meshing point, and small output flow fluctuation. At the same time, since there is no relative sliding between the tooth surfaces during the meshing process of the gear pair, it also has the advantages of no tooth surface wear, smooth operation, low noise, and long service life.

[0017] Furthermore, the radius r of the tooth top and tooth root are equal. In theoretical design, when the tooth root circle of one gear and the tooth top circle of another gear rotate to contact each other, the tooth root circle and the tooth top circle completely overlap and will not have any effect on the transmission of the two gears. This design is only to ensure the sealing effect. In order to avoid the phenomenon of stuck and noise in the meshing process of the gears, in actual manufacturing, the radius of the tooth top circle is slightly smaller than the radius of the tooth root circle.

[0018] Furthermore, the pitch n of the cylindrical helix is ​​7 mm, and the normal tooth profile arc radius ρ of the linear gear is 2.5 mm.

[0019] Furthermore, the line gear contact N is the number of teeth of the linear gear, Δt is the difference between the initial meshing point and the final meshing point t, and t is the parameter of the curve range.

[0020] Furthermore, the transmission ratio between the active double circular arc gear and the driven double circular arc gear is 1.

[0021] Furthermore, the contact line includes a first contact line and a second contact line, the first contact line and the second contact line are respectively located on the transition surfaces on both sides of the wire tooth, the first contact line and the second contact line have the same shape, and the central angle formed by the first contact line and the second contact line is π / N, where N is the number of wire teeth of the wire gear.

[0022] Furthermore, the number of wire teeth N is 5.

[0023] Further, the first contact line includes a first active contact line of the active double circular arc gear and a first driven contact line of the driven double circular arc gear, and the second contact line includes a second active contact line of the active double circular arc gear and a second driven contact line of the driven double circular arc gear;

[0024] The parametric equation of the first active contact line is,

[0025]

[0026] The parametric equation of the first driven contact line is:

[0027]

[0028] The parametric equation of the second active contact line is:

[0029]

[0030] The parametric equation of the second driven contact line is:

[0031]

[0032] Among them, t is the parameter variable of the curve range.

[0033] Furthermore, the binormal vector γ1 of the first active contact line (1) The parametric equation is,

[0034]

[0035] The secondary normal vector γ2 of the second active contact line (1) The parametric equation is,

[0036]

[0037] The binormal vector γ1 of the first driven contact line (2) The parametric equation is,

[0038]

[0039] The secondary normal vector γ2 of the second driven contact line (2) The parametric equation is,

[0040]

[0041] Among them, t is the parameter variable of the curve range.

[0042] Furthermore, the active double circular arc gear line teeth include a first active tooth surface and a second active tooth surface connected to each other, and the parameter equation of the first active tooth surface is:

[0043]

[0044] The parametric equation of the second active tooth surface is:

[0045]

[0046] The driven double circular arc gear line teeth include a first driven tooth surface and a second driven tooth surface connected to each other. The parameter equation of the first driven tooth surface is:

[0047]

[0048] The parametric equation of the second driven tooth surface is:

[0049]

[0050] Among them, t is the parameter variable of the curve range, and θ is the angle parameter of the normal tooth profile arc.

[0051] In general, the present invention has the following advantages:

[0052] 1. Eliminate the oil trapped phenomenon. The present invention proposes to use double circular arc gears to replace the traditional involute gears in the gear pump. Since the double circular arc gears are a new transmission mechanism designed based on the principle of spatial conjugate curve meshing, the end face overlap is 0, so the double circular arc gear pump will not form a closed oil trapped volume during operation, and the oil trapped phenomenon in the gear pump can be completely eliminated from the design theory.

[0053] 2. Low flow pulsation. Since the double arc gears are point contact transmission during the meshing process, the radial leakage at the gear meshing point of the pump is constant during operation and can be controlled according to the tooth profile design parameters, further improving the stability of the output flow of the gear pump.

[0054] 3. No wear between tooth surfaces, smooth operation, low noise and long service life. The sliding rate of the double arc gear pair is 0, and there is no relative sliding between tooth surfaces during gear meshing. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a schematic diagram of the planar structure of a double arc gear pump.

[0056] Figure 2 Schematic diagram of the normal tooth profile of a linear gear according to an embodiment of the present invention.

[0057] Figure 3 Schematic diagram of the end face tooth profile of a double arc gear according to an embodiment of the present invention.

[0058] Figure 4 Schematic diagram of the end face meshing state of the double circular arc gear pair according to an embodiment of the present invention.

[0059] Figure 5 It is a schematic diagram of the three-dimensional structure of a double arc gear pump.

[0060] Reference numerals:

[0061] 1-bearing box, 2-pump body, 3-bolt, 4-oil seal, 5-elastic retaining ring, 6-active double circular arc gear, 7-end cover, 8-cross screw, 9-second sealing ring, 10-driven double circular arc gear, 11-first sealing ring, 12-sliding bearing, 13-hexagonal nut, 14-first transition curve, 15-second transition curve. DETAILED DESCRIPTION

[0062] The present invention will be described in further detail below.

[0063] like Figure 1 , Figure 5 As shown, a double circular arc gear pump has a common three-piece overall structure, mainly composed of three parts: a bearing box 1, a pump body 2, and an end cover 7. The pump pump includes a bearing box 1, a pump body 2, bolts 3, an oil seal 4, a circlip 5, an active double circular arc gear 6, an end cover 7, a cross screw 8, a second sealing ring 9, a driven double circular arc gear 10, a first sealing ring 11, a sliding bearing 12, and a hexagonal nut 13. The active double circular arc gear 6 and the driven double circular arc gear 10 are both double circular arc gears with circular arc teeth at the tooth top and tooth root. The end face meshing state diagram of the double circular arc gear pair is shown in FIG. Figure 4 The driving double circular arc gear 6 and the driven double circular arc gear 10 are installed on the pump body 2, and two sliding bearings 12 are arranged at the right and left ends of the driving double circular arc gear 6 and the driven double circular arc gear 10. The sliding bearing 12 at the right end is installed on the pump body 2, and the sliding bearing 12 at the left end is installed on the bearing box 1. The bearing box 1 is arranged at the left end of the pump body 2. The first sealing ring 11 is arranged between the bearing box 1 and the pump body 2 and is installed in the sealing groove on the pump body 2. The bearing box 1 and the pump body 2 are fixedly connected to each other by four sets of bolts 3 and hexagonal nuts 13. The right end of the axle extends out from the sliding bearing 12 on the pump body 2, the oil seal 4 is arranged on the part of the axle of the active double circular arc gear 6 extending out of the pump body 2, and the oil seal 4 is installed on the end cover 7, the elastic retaining ring 5 is arranged on the right end of the oil seal 4 and installed on the end cover 7, the end cover 7 is arranged at the right end of the pump body 2, the second sealing ring 9 is arranged between the end cover 7 and the pump body 2, and is installed in the sealing groove on the end cover 7, the end cover 7 and the pump body 2 are fixedly connected to each other by three cross screws 8, the axle of the active double circular arc gear 6 extends out from the right end of the end cover 7, and the end is connected to the motor shaft through a double diaphragm coupling.

[0064] The double circular arc gear is a line gear based on the principle of meshing of spatial conjugate curves. In order to realize the forward and reverse bidirectional transmission of the double circular arc gear, there are two contact lines on each line tooth, which are distributed on the transition surfaces on both sides of the line tooth, namely the first contact line and the second contact line. The second contact line is obtained by rotating the gear shaft around the first contact line (π / N), where N is the number of teeth of the line gear. The number of teeth of the double circular arc gear in this embodiment is 5, and the tooth width B is 10mm.

[0065] The first contact line and the second contact line are both cylindrical helical lines, and the main parameters include the meshing radius m and the cylindrical helical line pitch parameter n. The first contact line includes a first active contact line and a first driven contact line, and the second contact line includes a second active contact line and a second driven contact line.

[0066] According to the conjugate curve meshing principle v 12 ·β=0, the equation of the driven contact line conjugate with the active contact line can be derived, where: 12 is the relative motion velocity at the meshing point, and β is the principal normal vector of the contact line.

[0067] The parametric equation of the first active contact line is as follows:

[0068]

[0069] The parametric equation of the first driven contact line is as follows:

[0070]

[0071] The parametric equation of the second active contact line is as follows:

[0072]

[0073] The parametric equation of the second driven contact line is as follows:

[0074]

[0075] Among them, t is the parameter variable of the curve range.

[0076] The pair of double arc line gear pairs in this embodiment meets the line gear overlap requirements: ε is the overlap of the linear gear, Δt is the difference between the initial meshing point and the final meshing point t, N is the number of teeth of the linear gear, and the transmission ratio i 12 is 1.

[0077] The tooth surface of the linear gear is obtained by scanning the normal tooth profile with the contact line as the scanning line and the center line as the guide line. Figure 2As shown, the normal tooth profile is a circular arc, and the contact point P is set on the circular arc. The distance between the center of the normal tooth profile arc and the contact point P is ρ, that is, the radius of the normal tooth profile arc of the linear gear. The angle between the straight line connecting the center of the normal tooth profile arc and the contact point P and -γ is γ is the binormal vector of the contact line.

[0078] The binormal vector γ1 of the first active contact line (1) The parametric equations are as follows:

[0079]

[0080] The secondary normal vector γ2 of the second active contact line (1) The parametric equations are as follows:

[0081]

[0082] The binormal vector γ1 of the first driven contact line (2) The parametric equations are as follows:

[0083]

[0084] The secondary normal vector γ2 of the second driven contact line (2) The parametric equations are as follows:

[0085]

[0086] Among them, t is the parameter variable of the curve range.

[0087] In this embodiment, the normal tooth profile arc radius ρ of the linear gear is 2.5 mm.

[0088] The first active contact line is moved along the binormal vector γ1 (1) The first active center line is obtained by translating in the opposite direction of the first normal tooth profile arc, and the angle between the straight line of the center of the first normal tooth profile arc and the contact point P and -γ The first normal tooth profile is scanned with the first active contact line as the scanning line and the first active center line as the guide line to obtain the first active tooth surface of the active linear gear. The parameter equation of the first active tooth surface is as follows:

[0089]

[0090] Among them, t is the parameter variable of the curve range, and θ is the angle parameter of the normal tooth profile arc.

[0091] The first normal tooth profile is symmetrically obtained along the main normal vector to obtain the second normal tooth profile, and the second active contact line is symmetrically obtained along the secondary normal vector γ2 (1)The second active center line is obtained by translating in the opposite direction of , and the second normal tooth profile is scanned with the second active contact line as the scanning line and the second active center line as the guide line to obtain the second active tooth surface of the active linear gear. The parameter equation of the second active tooth surface is as follows:

[0092]

[0093] Among them, t is the parameter variable of the curve range, and θ is the angle parameter of the normal tooth profile arc.

[0094] The first tooth surface and the second tooth surface are combined to obtain the complete tooth surface of a line tooth of the driving line gear, and the driving line gear is obtained by rotating the array. The end face tooth profile curve of the driving line gear is obtained by cutting the driving line gear at any end section. Figure 3 As shown, the end face tooth profile of the double circular arc gear in this embodiment is composed of three curves, the tooth top and tooth root are conjugate circular arc tooth profiles, and the radius r is equal. Preferably, r is 1.706mm. The gear pitch circle radius R is the meshing radius m of the contact line of the linear gear. The meshing radius m of a pair of double circular arc gears in this embodiment is 6mm. The transition curve is the end face tooth profile curve of the above-mentioned active linear gear, that is, the first transition curve 14 and the second transition curve 15, which are tangent to the tooth root arc and intersect with the tooth top arc respectively.

[0095] In this embodiment, the cylindrical helix pitch parameter n is 7 mm, and the active end face tooth profile is spirally rotated around the central axis to obtain the active double circular arc gear 6.

[0096] Similarly, the driven double circular arc gear 10 can be obtained. The parameter equation of the first driven tooth surface is as follows:

[0097]

[0098] The parametric equation of the second driven tooth surface is as follows:

[0099]

[0100] Among them, t is the parameter variable of the curve range, and θ is the angle parameter of the normal tooth profile arc.

[0101] The schematic diagram of the end face meshing state of the double arc gear pair in this embodiment is as follows: Figure 4As shown, during the meshing process of the double circular arc gear pair, based on the principle of spatial conjugate curve meshing, the active double circular arc gear 6 and the driven double circular arc gear 10 have only one contact point on the end face where the instantaneous meshing point is located, and the two gears are in a disengaged state on the other end faces, which not only does not form a closed oil trapped volume, thereby avoiding the oil trapped phenomenon in the gear pump, but also avoids the phenomenon that the instantaneous meshing line of the helical gear changes continuously during the meshing process. Since the radii of the tooth top and the tooth root are equal, the gap area at the gear meshing point will not change during the gear transmission process, thereby ensuring that the radial leakage at the gear meshing point is constant during the meshing process, further improving the stability of the gear pump output flow rate.

[0102] In this embodiment, the first transition curve 14 includes the first active transition curve of the active double circular arc gear 6 and the first driven transition curve of the driven double circular arc gear 10. The second transition curve 15 includes the second active transition curve of the active double circular arc gear 6 and the second driven transition curve of the driven double circular arc gear 10. Taking the height z of the end section as 0, we can obtain:

[0103] The parametric equation of the first active transition curve is,

[0104]

[0105] The parametric equation of the second active transition curve is,

[0106]

[0107] The parametric equation of the first driven transition curve is,

[0108]

[0109] The parametric equation of the second driven transition curve is:

[0110] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A double circular arc gear pump, comprising a pump body, characterized in that: The pump body is provided with an active double circular arc gear and a driven double circular arc gear of instantaneous single point meshing transmission; Both the active double circular arc gear and the driven double circular arc gear are linear gears provided with a plurality of linear teeth; The line teeth are provided with tooth tops, transition curved surfaces and tooth roots connected in sequence; The tooth top and tooth root are conjugate arc tooth shapes; The transition surface is tangent to the tooth root; The transition surface is provided with a contact line consisting of a plurality of instantaneous meshing points; The contact line is a cylindrical helix; The pitch radius of the line gear is equal to the meshing radius of the contact line; The contact line includes a first contact line and a second contact line, the first contact line and the second contact line are respectively located on transition surfaces on both sides of the line gear, the first contact line and the second contact line have the same shape, and the central angle formed by the first contact line and the second contact line is π / N, where N is the number of line teeth of the line gear; The number of line teeth N is 5; The first contact line includes a first active contact line of the active double circular arc gear and a first driven contact line of the driven double circular arc gear, and the second contact line includes a second active contact line of the active double circular arc gear and a second driven contact line of the driven double circular arc gear; The parametric equation of the first active contact line is, The parametric equation of the first driven contact line is: The parametric equation of the second active contact line is: The parametric equation of the second driven contact line is: Among them, t is the parameter variable of the curve range.

2. A double circular arc gear pump according to claim 1, characterized in that: The radius r of the tooth top and tooth root is equal.

3. A double circular arc gear pump according to claim 1, characterized in that: The pitch n of the cylindrical helix is ​​7 mm, and the radius ρ of the normal tooth profile arc of the linear gear is 2.5 mm.

4. A double circular arc gear pump according to claim 1, characterized in that: Line gear contact N is the number of teeth of the linear gear, Δt is the difference between the initial meshing point and the final meshing point t, and t is the parameter of the curve range.

5. A double circular arc gear pump according to claim 1, characterized in that: The transmission ratio of the active double circular arc gear and the driven double circular arc gear is 1.

6. A double circular arc gear pump according to claim 1, characterized in that: The binormal vector γ1 of the first active contact line (1) The parametric equation is, The secondary normal vector γ2 of the second active contact line (1) The parametric equation is, The binormal vector γ1 of the first driven contact line (2) The parametric equation is, The secondary normal vector γ2 of the second driven contact line (2) The parametric equation is, Among them, t is the parameter variable of the curve range.

7. A double circular arc gear pump according to claim 6, characterized in that: The active double circular arc gear line teeth include a first active tooth surface and a second active tooth surface connected to each other. The parameter equation of the first active tooth surface is: The parametric equation of the second active tooth surface is: The driven double circular arc gear line teeth include a first driven tooth surface and a second driven tooth surface connected to each other. The parameter equation of the first driven tooth surface is: The parametric equation of the second driven tooth surface is: Among them, t is the parameter variable of the curve range, and θ is the angle parameter of the normal tooth profile arc.

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