Vacuum pump, control method thereof, and braking device for agricultural machine

Abstract

The application provides a vacuum pump, a control method thereof and a braking device for agricultural machinery. A buffer area is concavely arranged at an impeller at a minimum extension position of a rotating cavity in a stator. The buffer area includes a first buffer area extending from an impeller at a maximum extension position to an impeller at the minimum extension position, and a second buffer area extending from the impeller at the minimum extension position to an impeller at an intermediate extension position. By arranging the buffer area on an inner wall of the rotating cavity of the stator, the impeller stroke near the minimum extension position is appropriately increased, thereby reducing the volume change of lubricating oil between adjacent impellers when the impeller moves from the maximum extension position to the minimum extension position and from the minimum extension position to the intermediate extension position, reducing the pressure change threshold range of the lubricating oil between adjacent impellers, avoiding unexpected damage to an oil inlet and an oil discharge plate caused by excessive pressure change, ensuring normal extension movement of the impeller, and improving the working efficiency of the vacuum pump.

Description

Technical Field

[0001] This invention relates to the technical field of agricultural machinery, specifically to a vacuum pump and its control method, as well as a braking device for agricultural machinery. Background Technology

[0002] Vacuum pumps in existing technology have been widely used in fields such as vehicle braking, achieving braking assistance by converting mechanical energy into hydraulic energy. The working principle of a vacuum pump is as follows: the rotor drives the outer peripheral blades to rotate synchronously in the internal cavity of the stator. During the rotation, the blades contact the inner wall of the stator and move in extension and contraction relative to their own expansion and contraction cavities, thereby changing the volume and pressure of the lubricating oil scraped between adjacent blades. When the pressure decreases, air is drawn from the air tank into the vacuum pump, and when the pressure increases, oil is discharged from the vacuum pump.

[0003] However, existing vacuum pumps still have the following defects and shortcomings during use:

[0004] 1) For vacuum pumps with a small number of impellers, when the impeller extension stroke between the maximum and minimum extension positions is large, the volume of lubricating oil between adjacent blades is large. When the rotor speed is too fast, the extension and contraction of the impeller will cause excessive instantaneous pressure changes during oil discharge and gas extraction. This will not only cause unexpected damage to the air inlet and oil discharge plate, but also affect the normal extension and contraction of the impeller, especially during gas extraction, thereby reducing the working efficiency of the vacuum pump.

[0005] 2) When the impeller's extension stroke is small between the maximum and minimum extension positions, it will lead to incomplete oil inlet and outlet, and the rotor and impeller cannot be effectively lubricated. At the same time, insufficient lubricating oil between adjacent impellers will also affect the extension and retraction of the impeller, and the working efficiency of the vacuum pump will also decrease accordingly.

[0006] Therefore, there is an urgent need to provide a vacuum pump that can maintain the pumping and oil discharge volumes at stable values, so that its working efficiency remains high and stable. Summary of the Invention

[0007] In order to overcome the defects and shortcomings of the existing technology, the present invention provides a vacuum pump and its control method, as well as a braking device for agricultural machinery.

[0008] The specific solution provided by this invention is as follows:

[0009] A vacuum pump includes a transmission device connected to a power source, an input end of an output shaft fixedly connected to the transmission device, an output end of the output shaft passing through a fixed plate and entering the interior of a housing, the housing being mounted on the side of the fixed plate away from the transmission device via a mounting plate, and an oil drain plate being mounted on the other side of the fixed plate near the transmission device.

[0010] The side of the housing away from the transmission device is connected to an oil inlet and a vent. The oil inlet is connected to an oil pump and communicates with the inside of the housing. The vent communicates with the inside of the housing through a one-way valve. The vent is connected to an air storage tank. The oil drain plate is provided with an oil drain port and an exhaust port.

[0011] A stator is fixedly installed inside the housing. A rotating cavity filled with lubricating oil is formed inside the stator. The output end of the output shaft is connected to the rotor through a splined shaft. Several telescopic cavities are opened on the outer periphery of the rotor. An impeller capable of telescopic movement relative to the telescopic cavity is arranged inside each telescopic cavity. The axis of the rotor is not concentric with the axis of the stator. The rotation of the rotor drives its outer impeller to rotate synchronously inside the stator. Under the contact with the inner wall of the stator, the impeller can telescopic movement relative to its respective telescopic cavity.

[0012] Its features are:

[0013] The rotating cavity inside the stator has a buffer zone arranged radially outward at the impeller at the minimum extension position. The buffer zone includes a first buffer zone extending from the impeller at the maximum extension position to the impeller at the minimum extension position, and a second buffer zone extending from the impeller at the minimum extension position to the impeller at the intermediate extension position.

[0014] And it satisfies the following condition: the first central angle formed by the first buffer zone relative to the rotor axis is greater than the second central angle formed by the second buffer zone relative to the rotor axis.

[0015] As a further preferred embodiment of the present invention, the buffer zone is crescent-shaped with thin ends and a thick middle.

[0016] As a further preferred embodiment of the present invention, the edge line of the buffer zone is selected from any one or more combinations of circular arc, parabola or hyperbola.

[0017] As a further preferred embodiment of the present invention, both the radial outer end and the radial inner end of the impeller are configured as arc surfaces, and when the radial outer end of the impeller slides in contact with the inner wall of the stator, the contact surface between the radial outer end of the impeller and the inner wall of the stator is greater than 1 / 2 of the radial outer end arc surface of the impeller and less than 2 / 3 of the radial outer end arc surface of the impeller.

[0018] As a further preferred embodiment of the present invention, a first transition zone is provided radially inward between the impeller at the maximum extension position and the impeller at the minimum extension position near the first buffer zone, and a second transition zone is provided radially inward between the impeller at the minimum extension position and the impeller at the intermediate extension position near the second buffer zone.

[0019] As a further preferred embodiment of the present invention, the third central angle formed by the first transition zone relative to the rotor shaft is greater than the fourth central angle formed by the second transition zone relative to the rotor shaft.

[0020] As a further preferred embodiment of the present invention, the third central angle formed by the first transition zone relative to the rotor shaft is smaller than the second central angle formed by the second buffer zone relative to the rotor shaft.

[0021] As a further preferred embodiment of the present invention, the maximum radial dimension of the buffer is greater than the maximum radial dimension of the first transition region and the second transition region.

[0022] Furthermore, the present invention also provides a method for controlling a vacuum pump, characterized by comprising the following steps:

[0023] 1) The power source outputs power and drives the output shaft to rotate via a transmission device;

[0024] 2) While the output shaft drives the rotor to rotate inside the rotating cavity of the stator, the impellers on the outer periphery of the rotor also rotate synchronously with the rotor and, under the contact with the inner wall of the stator, each impeller performs a telescopic movement relative to its respective telescopic cavity.

[0025] 3) When the impeller moves from the maximum extension position to the minimum extension position, the volume of lubricating oil between adjacent impellers decreases and the pressure increases. The lubricating oil and gas inside the casing are discharged through the oil drain port and exhaust port on the oil drain plate respectively.

[0026] 3.1) When the impeller moves to the first transition zone, because the first transition zone is set radially inward, the volume of lubricating oil between adjacent impellers located at the maximum extension position and the minimum extension position decreases briefly and the pressure increases briefly.

[0027] 3.2) When the impeller moves into the first buffer zone, the first buffer zone is radially outward, which allows the lubricating oil between adjacent impellers, whose pressure increases briefly, to be fully discharged.

[0028] 4) When the impeller moves from the minimum extension position to the middle extension position, the volume of lubricating oil between adjacent impellers increases and the pressure decreases. Gas in the gas tank enters the shell through the one-way valve, and a vacuum is formed in the gas tank.

[0029] 4.1) When the impeller moves to the second buffer zone, because the first buffer zone is set radially outward, the lubricating oil between adjacent impellers can be continuously and fully discharged at the same time;

[0030] 4.2) When the impeller moves to the second transition zone, because the second transition zone is set radially inward, the volume of lubricating oil between adjacent impellers located at the minimum extension position and the intermediate extension position decreases briefly and the pressure increases briefly.

[0031] 5) When the impeller moves from the middle extension position to the maximum extension position, the volume of lubricating oil between adjacent impellers increases and the pressure decreases, and the lubricating oil enters the housing through the oil inlet.

[0032] Furthermore, the present invention also provides a braking device for agricultural machinery, characterized in that: the braking device includes the aforementioned vacuum pump.

[0033] Compared with existing technologies, the technical effects that this invention can achieve include:

[0034] 1) This invention provides a vacuum pump and its control method, as well as a braking device for agricultural machinery. By setting a buffer zone on the inner wall of the stator rotating cavity, the impeller stroke near the minimum extension position is appropriately increased. This reduces the volume change of lubricating oil between adjacent impellers when the impeller moves from the maximum extension position to the minimum extension position and from the minimum extension position to the intermediate extension position. This reduces the pressure change threshold range between adjacent impellers, avoids unexpected damage to the vent and oil discharge plate caused by excessive pressure changes, ensures the normal extension and retraction movement of the impeller, and improves the working efficiency of the vacuum pump.

[0035] 2) This invention provides a vacuum pump and its control method, as well as a braking device for agricultural machinery. By setting a first transition zone and a second transition zone on both sides of the buffer zone, the volume and pressure changes of the lubricating oil between adjacent impellers are further reduced when moving from the maximum extension position to the minimum extension position and from the minimum extension position to the intermediate extension position. This transforms the volume and pressure changes of a single large stroke into multiple small strokes, protecting the vent and the oil drain plate. While ensuring the working efficiency of the vacuum pump, it also offsets the reduction in vacuum pump working efficiency caused by insufficient lubricating oil due to the buffer zone setting. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of the present invention.

[0037] Figure 2 This is a side view of the structure of the present invention.

[0038] Figure 3 This is a cross-sectional view of the present invention along the vertical direction.

[0039] Figure 4 This is a cross-sectional view of the invention along the horizontal direction.

[0040] Figure 5 for Figure 4 Enlarged view of the structure at the location of the middle buffer zone.

[0041] Figure 6This is a schematic diagram illustrating the change in lubricating oil volume between adjacent impellers when the impeller moves from its maximum extension position to its minimum extension position. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0044] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0045] [First Embodiment]

[0046] like Figure 1-5 The image shows a vacuum pump provided in the first embodiment of the present invention, such as... Figure 1-3 As shown, the vacuum pump includes a transmission device 1 connected to a power source. In this embodiment, the transmission device 1 is a transmission gear. Those skilled in the art know that, in order to meet the transmission requirements, the transmission device can also be replaced with a bevel gear, a conveyor belt, or other common transmission devices in the art, depending on actual needs. The input end of the output shaft 6 is fixedly connected to the transmission device 1. The output end of the output shaft 6 passes through the fixed plate 2 and enters the interior of the housing 3. Under the drive of the power source, the output shaft 6 rotates synchronously inside the housing 3. The housing 3 is mounted on the side of the fixed plate 2 away from the transmission device 1 by means of a mounting plate 4 and bolts. An oil drain plate 5 is also mounted on the other side of the fixed plate 2 near the transmission device 1 by bolts.

[0047] On the side of the housing 3 away from the transmission device 1, there is also an oil inlet 9 and a vent 11. The oil inlet 9 is connected to the inside of the housing 3 and is connected to an oil pump to realize the entry and discharge of lubricating oil inside the housing 3. The vent 11 is connected to an air tank to introduce gas into the housing 3. When the air pressure inside the housing 3 decreases, the lubricating oil and gas enter the housing through the oil inlet 9. When the pressure inside the housing 3 increases, they are discharged from the housing through the corresponding oil drain and air vent on the oil drain plate 5. The vent 11 is connected to the inside of the housing 3 through a one-way valve 10 to adjust the pressure inside the housing 3 in real time.

[0048] A stator D is fixedly installed inside the housing 3. A rotating cavity S filled with lubricating oil is formed inside the stator D. The output end of the output shaft 6 is connected to the rotor Z through a splined shaft 8. Several telescopic cavities C are opened on the outer periphery of the rotor Z. Impellers Y1, Y2, and Y3 that can telescopically move relative to the telescopic cavity C are arranged inside each telescopic cavity C. The axis of the rotor Z is not concentric with the axis of the stator D. The rotation of the rotor Z drives its outer peripheral impellers Y1, Y2, and Y3 to rotate synchronously inside the stator D. Under the contact with the inner wall of the stator, the impellers can telescopically move relative to their respective telescopic cavities C. Since the axis of the rotor Z is not concentric with the axis of the stator D, the distance between the outer periphery of the rotor Z and the inner wall of the stator D will change when the rotor Z rotates inside the rotating cavity S. Therefore, the telescopic position of the impellers needs to be changed accordingly during the contact with the inner wall of the stator D.

[0049] In this embodiment, as Figure 4 As shown, three impellers Y1, Y2, and Y3 are evenly distributed on the outer circumference of rotor Z. At this time, impeller Y1 is in the maximum extension position, Y2 is in the minimum extension position, and Y3 is in the middle extension position. Extension cavities C are evenly opened on the outer circumference of rotor Z. The extension cavities extend radially along rotor Z. The three impellers Y1, Y2, and Y3 can extend and retract in their respective extension cavities C.

[0050] In this embodiment, as Figure 5 As shown, the radial outer and radial inner ends of impellers Y1, Y2, and Y3 are all set as arc surfaces. When the radial outer ends of impellers Y1, Y2, and Y3 slide in contact with the inner wall of stator D, the contact area between the radial outer ends of impellers Y1, Y2, and Y3 and the inner wall of stator D is greater than 1 / 2 and less than 2 / 3 of the radial outer arc surface of impellers Y1, Y2, and Y3. The purpose of this setting is to ensure that the radial outer end of the impeller can maintain good contact with the inner wall of stator D, regardless of whether the rotor Z rotates forward or backward inside stator D, and to effectively achieve sealing between adjacent blades, preventing lubricating oil from leaking between the radial outer end of the impeller and the inner wall of stator D.

[0051] like Figure 5As shown, the improvement of this embodiment compared to the prior art is that the rotating cavity S inside the stator D is radially outward at the impeller Y2 at the minimum extension position (relative to a regular circle with the stator D axis as the center and the distance between the stator D axis and the inner wall of other positions as the radius, i.e., as shown in the attached figure). Figure 4-5 As shown, there is a buffer zone Q, which includes a first buffer zone Q1 extending from the impeller Y1 at the maximum extension position to the impeller Y2 at the minimum extension position, and a second buffer zone Q2 extending from the impeller Y2 at the minimum extension position to the impeller Y3 at the intermediate extension position. By setting a buffer zone on the inner wall of the stator rotating cavity, the impeller stroke near the minimum extension position is appropriately increased. This reduces the volume change of lubricating oil between adjacent impellers when the impeller moves from the maximum extension position to the minimum extension position and from the minimum extension position to the intermediate extension position. This reduces the pressure change threshold range inside the housing between adjacent impellers, avoids unexpected damage to the vent and oil drain plate caused by excessive pressure changes, ensures the normal extension and retraction movement of the impeller, and improves the working efficiency of the vacuum pump.

[0052] As a further preferred embodiment, the first central angle J1 formed by the first buffer zone Q1 relative to the rotor Z axis is greater than the second central angle J2 formed by the second buffer zone Q2 relative to the rotor Z axis. The purpose of this arrangement is that, since the lubricating oil enters the housing 3 from the oil inlet 9 during oil intake, the lubricating oil can stay at the oil inlet 9 for a period of time, thereby absorbing some of the impact on the rotor Z and impeller caused by the suction oil intake. During oil discharge, the oil passes through the rotor Z and impeller and is directly discharged from the oil discharge hole on the oil discharge plate 5. Therefore, it is necessary to achieve a larger range of buffering during oil discharge. Thus, the larger the central angle, the earlier the range of change in the extension length of the impeller can be reduced when moving from the maximum extension position to the minimum extension position, so that it can enter the buffer zone earlier, and thus achieve a larger range of buffering earlier during oil discharge.

[0053] In this embodiment, as Figure 5 As shown, the buffer zone Q is crescent-shaped, tapering at both ends and thickening in the middle. This shape not only facilitates the machining and manufacturing of the stator D, but also allows for smooth sliding contact between the outer radial end of the impeller and the inner wall of the stator D. As a further preferred embodiment, the edge line L of the buffer zone Q is preferably an arc to facilitate machining, forming, and installation positioning. Those skilled in the art will understand that, to achieve different rotational trajectories, the edge line L of the buffer zone Q can be set as any combination of one or more of a parabola or hyperbola, depending on actual needs.

[0054] As another improvement of this embodiment compared to the prior art: such as Figure 5As shown, in this embodiment, the impeller Y1 at its maximum extension position and the impeller Y2 at its minimum extension position are located radially inward near the first buffer zone Q1 (relative to a regular circle with the stator D axis as the center and the distance between the stator D axis and the inner walls of other positions as the radius, i.e., as shown in the attached figure). Figure 4-5 As shown, a first transition zone Q3 is provided. The impeller Y2 at its minimum extension position and the impeller Y3 at its intermediate extension position are located near the second buffer zone Q3, and the zone extends radially inward (relative to a regular circle centered on the stator D axis, with the distance between the stator D axis and the inner walls of other positions as the radius, i.e., as shown in the attached diagram). Figure 4-5 As shown, a second transition zone Q4 is provided; thereby further reducing the volume and pressure changes of the lubricating oil between adjacent impellers when moving from the maximum extension position to the minimum extension position, and from the minimum extension position to the intermediate extension position, transforming the volume and pressure changes of a single large stroke into multiple small stroke volume and pressure changes, protecting the vent and oil drain plate, ensuring the working efficiency of the vacuum pump, and offsetting the reduction in vacuum pump working efficiency caused by insufficient lubricating oil due to the setting of the buffer zone.

[0055] As a further preferred embodiment, the third central angle J3 formed by the first transition zone Q3 relative to the rotor Z-axis is greater than the fourth central angle J4 formed by the second transition zone Q4 relative to the rotor Z-axis. To ensure that the lubricating oil inside the housing 3 can be discharged as much as possible to guarantee its assist effect during vacuum braking, and to ensure that sufficient lubricating oil can be drawn in during subsequent oil suction after being emptied as much as possible, the third central angle J3 formed by the first transition zone Q3 relative to the rotor Z-axis is set to be greater than the fourth central angle J4 formed by the second transition zone Q4 relative to the rotor Z-axis. This allows the impeller to transform the volume and pressure changes of a single large stroke into multiple small stroke volume and pressure changes as early as possible during its rotation from the maximum extension position to the minimum extension position.

[0056] As a further preferred embodiment, the third central angle J3 formed by the first transition zone Q3 relative to the rotor Z-axis is smaller than the second central angle J2 formed by the second buffer zone Q2 relative to the rotor Z-axis; and the maximum radial dimension of the buffer zone Q is greater than the maximum radial dimension of the first transition zone Q3 and the second transition zone Q4. Since the first transition zone Q3 and the second transition zone Q4 are set to assist the buffer zone Q in forming sufficient volume and pressure changes, thereby facilitating the occurrence of air extraction and oil discharge, the setting range and radial dimension of the first transition zone Q3 and the second transition zone Q4 should not be higher than the setting range and radial dimension of the buffer zone.

[0057] [Second Embodiment]

[0058] This embodiment also provides a vacuum pump control method as in the first embodiment, including the following steps:

[0059] 1) The power source outputs power to drive the output shaft to rotate via a transmission device; the power source can be a motor or other commonly used power source in this field, and the transmission device can be a transmission gear or a conveyor belt or other transmission device according to actual transmission needs.

[0060] 2) While the output shaft drives the rotor to rotate inside the rotating cavity of the stator, the impellers on the outer periphery of the rotor can also rotate synchronously with the rotor and, under the contact with the inner wall of the stator, each impeller performs a telescopic movement relative to its respective telescopic cavity.

[0061] 3) When the impeller moves from the maximum extension position to the minimum extension position, the volume of lubricating oil between adjacent impellers decreases and the pressure increases. The lubricating oil and gas inside the casing are discharged through the oil drain port and exhaust port on the oil drain plate.

[0062] 3.1) When the impeller moves to the first transition zone, because the first transition zone is set radially inward, the volume of lubricating oil between adjacent impellers at the maximum extension position and the minimum extension position decreases and the pressure increases briefly. This ensures that the lubricating oil inside the housing 3 can be discharged as much as possible to ensure its assist effect during vacuum braking. After being emptied as much as possible, sufficient lubricating oil can be introduced in the subsequent oil inlet process, so that during the process of the impeller rotating from the maximum extension position to the minimum extension position, the volume and pressure changes of a single large stroke can be transformed into multiple small stroke volume and pressure changes as early as possible.

[0063] 3.2) When the impeller moves into the first buffer zone, the first buffer zone is radially outward, which allows the lubricating oil between adjacent impellers, whose pressure increases briefly, to be fully discharged.

[0064] 4) When the impeller moves from the minimum extension position to the middle extension position, the volume of lubricating oil between adjacent impellers increases and the pressure decreases. The lubricating oil enters the housing through the oil inlet, and at the same time, the gas in the gas tank enters the housing through the one-way valve, forming a vacuum in the gas tank.

[0065] 4.1) When the impeller moves to the second buffer zone, the first buffer zone is set radially outward, which allows the lubricating oil between adjacent impellers to be continuously and fully discharged;

[0066] 4.2) When the impeller moves to the second transition zone, because the second transition zone is set radially inward, the volume of lubricating oil between adjacent impellers located at the minimum extension position and the intermediate extension position decreases and the pressure increases for a short time. This allows the impeller to transform the volume and pressure changes of a single large stroke into multiple small stroke volume and pressure changes during the rotation of the impeller from the minimum extension position to the intermediate extension position, reducing the unintended damage to the vent caused by excessive pressure changes.

[0067] 5) When the impeller moves from the middle extension position to the maximum extension position, the volume of lubricating oil between adjacent impellers increases and the pressure decreases, and the lubricating oil enters the housing through the oil inlet.

[0068] By introducing the buffer Q, the volume and pressure changes of a single large stroke are transformed into multiple small stroke volume and pressure changes, protecting the air inlet and oil drain plate. This ensures the working efficiency of the vacuum pump while offsetting the potential reduction in vacuum pump efficiency due to insufficient lubricating oil caused by the buffer setting.

[0069] like Figure 6 As shown,

[0070] Without setting buffer zones and first and second transition zones, the change in lubricating oil volume between adjacent impellers when moving from the maximum extension position to the minimum extension position is shown by line A1 in the figure.

[0071] When a buffer zone is set, the change in lubricating oil volume between adjacent impellers when moving from the maximum extension position to the minimum extension position is shown by the solid line at position A2 in the figure; by setting a buffer zone Q, the threshold for the change in lubricating oil volume between adjacent impellers can be reduced.

[0072] When buffer zones and first and second transition zones are set simultaneously, the change in lubricating oil volume between adjacent impellers when moving from the maximum extension position to the minimum extension position is shown by the dotted line at position A2 in the figure. The setting of the first and second transition zones transforms the volume and pressure changes of a single large stroke into multiple small stroke volume and pressure changes, reducing the potential for unintended damage to the vent and oil drain plate caused by excessive pressure changes.

[0073] By setting buffer zones and first and second transition zones, the threshold for the change in lubricating oil volume between adjacent impellers is reduced, while ensuring sufficient pressure for the lubricating oil to be discharged. Since the radial dimensions of the buffer zones and first and second transition zones are very small, the bending distance shown by the dashed line at position A2 in the figure is actually very small and does not affect the normal rotation of the impeller.

[0074] [Third Embodiment]

[0075] This embodiment also provides a braking device for agricultural machinery, the braking device including the vacuum pump proposed in the first embodiment.

[0076] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A vacuum pump, comprising a transmission device (1) connected with a power source, an input end of an output shaft (6) being fixedly connected with the transmission device (1), an output end of the output shaft (6) penetrating through a fixed plate (2) into an inside of a housing (3), the housing (3) being installed on a side of the fixed plate (2) away from the transmission device (1) through a mounting plate (4), and an oil discharge plate (5) being further installed on another side of the fixed plate (2) close to the transmission device (1); an oil inlet (9) and a vent (11) being connected with the side of the housing (3) away from the transmission device (1), the oil inlet (9) being connected with an oil inlet pump and being in communication with the inside of the housing (3), the vent (11) being in communication with the inside of the housing (3) through a one-way valve (10), the vent (11) being connected with a gas storage tank, and an oil discharge port and a gas discharge port being formed on the oil discharge plate (5); a stator (D) being fixedly installed in the inside of the housing (3), a rotating cavity (S) filled with lubricating oil being formed in the inside of the stator (D), the output end of the output shaft (6) being connected with a rotor (Z) through a spline shaft (8), a plurality of expansion cavities (C) being formed on an outer periphery of the rotor (Z), an impeller (Y1, Y2, Y3) capable of expansion and contraction relative to each expansion cavity (C) being arranged in the inside of each expansion cavity (C), an axis of the rotor (Z) being different from an axis of the stator (D), the rotor (Z) rotating to drive the outer periphery impellers (Y1, Y2, Y3) to synchronously rotate in the inside of the stator (D) and the impellers (Y1, Y2, Y3) being capable of expansion and contraction relative to the respective expansion cavities (C) under the abutment with the inner wall of the stator; characterized in that: a buffer zone (Q) is arranged radially outward of the impeller (Y2) at the minimum expansion position in the rotating cavity (S) in the inside of the stator (D), the buffer zone (Q) comprising a first buffer zone (Q1) extending from the impeller (Y1) at the maximum expansion position to the impeller (Y2) at the minimum expansion position, and a second buffer zone (Q2) extending from the impeller (Y2) at the minimum expansion position to the impeller (Y3) at the intermediate expansion position; and the first central angle (J1) of the first buffer zone (Q1) relative to the axis of the rotor (Z) is greater than the second central angle (J2) of the second buffer zone (Q2) relative to the axis of the rotor (Z); an edge line (L) of the buffer zone (Q) is selected from any one or a combination of a circular arc line, a parabolic line or a hyperbolic line; the radial outer end and the radial inner end of the impeller (Y1, Y2, Y3) are both arranged as a circular arc surface, and when the radial outer end of the impeller (Y1, Y2, Y3) is in sliding contact with the inner wall of the stator (D), the contact surface of the radial outer end of the impeller (Y1, Y2, Y3) with the inner wall of the stator (D) is greater than 1 / 2 of the radial outer end circular arc surface of the impeller (Y1, Y2, Y3) and less than 2 / 3 of the radial outer end circular arc surface of the impeller (Y1, Y2, Y3). A first transition zone (Q3) is further radially inwardly arranged at a position close to the first buffer zone (Q1) between the impeller in the maximum retraction position (Y1) and the impeller in the minimum retraction position (Y2), and a second transition zone (Q4) is further radially inwardly arranged at a position close to the second buffer zone (Q2) between the impeller in the minimum retraction position (Y2) and the impeller in the intermediate retraction position (Y3); A third central angle (J3) formed by the first transition zone (Q3) relative to the axis of the rotor (Z) is greater than a fourth central angle (J4) formed by the second transition zone (Q4) relative to the axis of the rotor (Z); The third central angle (J3) formed by the first transition zone (Q3) relative to the axis of the rotor (Z) is smaller than a second central angle (J2) formed by the second buffer zone (Q2) relative to the axis of the rotor (Z); The maximum radial dimension of the buffer zone (Q) is greater than the maximum radial dimension of the first transition zone (Q3) and the second transition zone (Q4).

2. A vacuum pump according to claim 1, characterized in that: The buffer zone (Q) is in the shape of a crescent with thin ends and a thick middle.

3. A method of controlling a vacuum pump as claimed in any one of the claims 1-2, characterized in that: The method comprises the following steps: 1) The power source outputs power which drives the output shaft to rotate through the transmission device; 2) The output shaft drives the rotor to rotate in the rotating cavity inside the stator, and the outer peripheral impeller of the rotor also rotates synchronously with the rotor and performs retraction movement relative to the respective retraction cavity under the resistance of the inner wall of the stator; 3) When the impeller moves from the maximum retraction position to the minimum retraction position, the volume of the lubricating oil between the adjacent impellers decreases and the pressure increases, and the lubricating oil and gas in the housing are discharged through the oil discharge port and the gas discharge port on the oil discharge plate; 3.1) When the impeller moves to the first transition zone, the first transition zone is arranged radially inwardly, so that the volume of the lubricating oil between the adjacent impellers in the maximum retraction position and the minimum retraction position decreases and the pressure increases temporarily; 3.2) When the impeller moves to the first buffer zone, the first buffer zone is arranged radially outwardly, so that the lubricating oil between the adjacent impellers with temporarily increased pressure can be fully discharged; 4) When the impeller moves from the minimum retraction position to the intermediate retraction position, the volume of the lubricating oil between the adjacent impellers increases and the pressure decreases, the lubricating oil enters the housing through the oil inlet, and the gas in the gas storage tank enters the housing inside through the one-way valve, and a vacuum is formed in the gas storage tank; 4.1) When the impeller moves to the second buffer zone, the first buffer zone is arranged radially outwardly, so that the lubricating oil between the adjacent impellers can be continuously and fully discharged; 4.2) When the impeller moves to the second transition zone, the second transition zone is arranged radially inwardly, so that the volume of the lubricating oil between the adjacent impellers in the minimum retraction position and the intermediate retraction position decreases and the pressure increases temporarily; 5) When the impeller moves from the intermediate retraction position to the maximum retraction position, the volume of the lubricating oil between the adjacent impellers increases and the pressure decreases, and the lubricating oil enters the housing through the oil inlet.

4. A braking device for an agricultural machine, characterized by: The brake device comprises the vacuum pump according to any one of claims 1-2.

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