Liquid pump driven by PMDC motor and motor control system and method

Abstract

The invention relates to a liquid pump driven by a PMDC motor and a motor control system and method.The liquid pump comprises a pump shell used for being connected with the PMDC motor, an upper cover connected with the pump shell and provided with an opening allowing liquid to circularly enter and exit, and a shaft seal used for being connected with a driving shaft of the PMDC motor in a sleeving mode and arranged in the pump shell; the inner gear rotor is arranged in the pump shell and used for being connected with the driving shaft, the outer gear rotor is eccentrically connected with the inner gear rotor in a sleeved mode, and the first sealing ring and the second sealing ring are connected to the upper cover and the pump shell in a clamped mode respectively. The liquid pump can be driven by the PMDC motor, liquid can be effectively prevented from entering the PMDC motor through multi-position sealing design, and the liquid pump can be applied to various cooling systems and lubricating systems; meanwhile, the PMDC motor is controlled to enter a low-power, low-current and low-voltage cold start mode in a mode of gradually increasing the input power, potential safety hazards can be effectively avoided, and the service life of equipment is prolonged.

Description

[0001] The present application relates to the technical field of liquid pumps, in particular to a liquid pump driven by a PMDC motor and a motor control system and method.

[0002] At present, PMDC motors (Permanent Magnet Brushed DC) are only applied to fuel pumps and plunger pumps in motor vehicle engine systems, and are not applied to various cooling systems and lubricating systems, such as engine cooling systems and lubricating systems. The stator of the PMDC motor includes a cylindrical shell and a permanent magnet mounted to the inner wall of the shell; the rotor includes a rotating shaft, a commutator fixedly sleeved to the rotating shaft, a rotor magnetic core fixedly sleeved to the rotating shaft, and a winding wound to the rotor magnetic core; the winding is electrically connected to the corresponding commutating pieces of the commutator. The stator needs to be in conductive contact with the commutating pieces of the commutator through the brush, so as to supply power to the winding of the rotor. When the PMDC motor works, the rotor rotates, and the commutator rotates with it. During the rotation process, different commutating pieces are in turn in contact with the brush to realize current commutation. If the PMDC motor is permeated with liquid (such as cooling liquid or lubricating oil, etc.), it will easily cause problems in the conduction between the brush and the commutator.

[0003] Since the BLDC (Brushless Direct Current) motor does not need a brush and a commutator for conduction and can be immersed in liquid, in the cooling system and the lubricating system, the BLDC motor plus a G rotor pump is usually used. However, this method needs an expensive controller to detect the rotating position of the rotor and control current commutation, and the volume is large and the cost is very high. The English name of the G rotor pump is Gerotor type pumps, which is a kind of electric motor driven pump, especially a gear oil pump type pump, which is often used as a fuel pump, an oil pump with a hydraulic motor and a power steering unit.

[0004] Therefore, it is urgent to provide a liquid pump driven by a PMDC motor and a motor control system and method which can be applied to various cooling systems and lubricating systems, have low cost and small volume.

[0005] The technical problem to be solved by the present application is to provide a liquid pump driven by a PMDC motor and a motor control system and method which can be applied to engine cooling systems and lubricating systems.

[0006] ​​​To solve the above-mentioned technical problems, the present invention provides a liquid pump driven by a PMDC motor, comprising a pump housing for connecting the PMDC motor, an upper cover connected to the pump housing and having an opening for liquid circulation in and out, a shaft seal for fitting the drive shaft of the PMDC motor and being built into the pump housing, an internal gear rotor built into the pump housing and for connecting the drive shaft, an external gear rotor eccentrically fitted with the internal gear rotor, and a first sealing ring and a second sealing ring respectively snapped onto the upper cover and the pump housing.

[0007] Furthermore, the top cover includes a plane connecting the pump housing, an inlet provided on the plane for liquid circulation, a main outlet provided on the plane for liquid circulation, a threaded rod extending vertically upward from the plane, and a first through hole penetrating the plane and the threaded rod and coaxial with the top cover.

[0008] An outlet wall covering the main outlet is provided in the annular space between the outer wall of the first through hole and the inner wall of the screw post;

[0009] The outer wall of the dial indicator column is provided with an outlet for liquid circulation on the side adjacent to the outlet wall, and the outer wall of the dial indicator column is also provided with a first groove for engaging the first sealing ring.

[0010] Furthermore, the two ends of the outlet wall are connected to the inlet, and the middle is an arched curved surface.

[0011] Furthermore, the pump housing includes a contact surface connected to the top cover, a first annular groove, a second annular groove, and a third annular groove coaxial with the contact surface, a groove, a threaded hole, a positioning hole, and a positioning post connected to the positioning hole provided on the contact surface, and a second slot provided on the outer wall of the pump housing to engage the second sealing ring.

[0012] The bottom surface of the first annular groove is provided with a second through hole that is coaxial with the first annular groove and penetrates the pump casing, and the shaft seal is placed on the first annular groove;

[0013] The bottom surface of the third annular groove is provided with a connection hole for connecting the PMDC motor and a fixing hole for connecting an external system.

[0014] Furthermore, the second annular groove is located between the first annular groove and the third annular groove, engaging the front end face of the PMDC motor.

[0015] Furthermore, the external gear rotor and the internal gear rotor are placed within the groove.

[0016] Furthermore, the groove is provided with a shallow groove-shaped flow channel that matches the shape of the inlet and the main outlet.

[0017] Furthermore, the shaft seal includes an annular concave ring and a spring that engages with the inner wall of the concave ring.

[0018] To solve the above-mentioned technical problems, the present invention also provides a motor control system, including a ripple current detection unit for detecting the ripple current of a PMDC motor as described above, and a pulse width modulation unit connecting the ripple current detection unit and the PMDC motor.

[0019] The pulse width modulation unit gradually increases the input power of the PMDC motor from low to high through pulse width modulation; and receives the ripple current value of the PMDC motor sent by the ripple current detection unit, and stops increasing the input power when the ripple current value of the PMDC motor reaches a preset limit value.

[0020] The ripple current detection unit detects the ripple current value generated when the PMDC motor starts in real time and feeds it back to the pulse width modulation unit.

[0021] Furthermore, the pulse width modulation unit determines whether the ripple current value is abnormal; if so, it stops increasing the input power.

[0022] Furthermore, the pulse width modulation unit is connected to an external pulse width control system and adjusts the input power accordingly based on the control of the external pulse width control system.

[0023] Furthermore, when the pulse width modulation unit detects an abnormality in the ripple current value, it feeds back the abnormality information to the external pulse width control system.

[0024] To address the aforementioned technical problems, the present invention also provides a motor control method for controlling the aforementioned PMDC motor, comprising the following steps:

[0025] S1. The input power of the PMDC motor is gradually increased from low to high through pulse width modulation, and the ripple current value generated when the PMDC motor starts is detected in real time.

[0026] S2. When the ripple current value of the PMDC motor reaches a preset limit value, stop increasing the input power.

[0027] Furthermore, step S2 also includes: determining whether the ripple current value is abnormal; if so, stopping the increase of the input power.

[0028] Furthermore, step S1 also includes: adjusting the input power according to the control of the external pulse width control system.

[0029] Furthermore, step S2 also includes: when an abnormality is detected in the ripple current value, feeding back abnormal information to the external pulse width control system.

[0030] Compared with the prior art, the present invention has the following beneficial effects: the liquid pump of the present invention can be driven by a PMDC motor, and through multiple sealing designs, it can effectively prevent liquid from entering the interior of the PMDC motor, and can be applied to various cooling systems and lubrication systems; at the same time, by gradually increasing the input power, the PMDC motor is controlled to enter a cold start mode with low power, low current, and low voltage, which can effectively avoid safety hazards and extend the service life of the equipment. [Attached Image Description]

[0031] Figure 1 This is an external structural diagram of the liquid pump and PMDC motor according to an embodiment of the present invention;

[0032] Figure 2 This is an exploded structural diagram of the liquid pump and PMDC motor according to an embodiment of the present invention;

[0033] Figure 3 This is a reverse structural view of the upper cover of the liquid pump according to an embodiment of the present invention;

[0034] Figure 4 This is a front view of the upper cover structure of the liquid pump according to an embodiment of the present invention;

[0035] Figure 5 This is a cross-sectional view of the liquid pump and PMDC motor according to an embodiment of the present invention;

[0036] Figure 6 This is a block diagram of the motor control system according to an embodiment of the present invention;

[0037] Figure 7 This is a flowchart of the motor control method according to an embodiment of the present invention.

[0038] Labeling Explanation: 1. PMDC Motor; 2. Liquid Pump; 3. Top Cover; 4. Internal Gear Rotor; 5. External Gear Rotor; 6. Groove; 7. Flow Channel; 8. Threaded Hole; 9. Pump Housing; 10. Fixing Hole; 11. Shaft Seal; 12. Drive Shaft; 13. Double Flat Structure; 14. Second Screw; 15. Spring; 16. Second Sealing Ring; 17. First Sealing Ring; 18. Positioning Hole; 19. Positioning Pin; 20. Gear Hole; 21. Bayonet; 22. Main Outlet; 23. 24. Import; 25. First screw; 26. Positioning wall; 27. Outlet wall; 28. From outlet; 29. ​​Reinforcing rib; 30. First through hole; 31. Annular space; 32. Ring post; 33. First slot; 34. Arc-shaped surface; 35. Second slot; 36. Second through hole; 37. Connecting hole; 38. Recessed ring; 39. Front cover; 40. Front end face; 41. First annular groove; 42. Second annular groove; 43. Third annular groove; 44. Contact surface; 45. Plane.

Detailed Implementation Methods

[0039] 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 this application, 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.

[0040] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate to allow implementation in orders other than those specified in the embodiments of the present invention.

[0041] Please refer to Figure 1 and Figure 2 As shown, the liquid pump 2 driven by the PMDC motor in this embodiment of the invention includes a pump housing 9 for connecting the PMDC motor 1, an upper cover 3 connected to the pump housing 9 and provided with an opening for liquid circulation, a shaft seal 11 for sleeved on the drive shaft 12 of the PMDC motor 1 and built into the pump housing 9, an internal gear rotor 4 built into the pump housing 9 and used for connecting the drive shaft 12, an external gear rotor 5 eccentrically sleeved with the internal gear rotor 4, and a first sealing ring 17 and a second sealing ring 16 respectively snapped onto the upper cover 3 and the pump housing 9.

[0042] In this embodiment, the upper cover 3 and the pump housing 9 are fixedly connected by a first screw 24 and a positioning post 19. A connection hole 36 is provided on the outer wall of the pump housing 9, which is connected to the front cover 38 of the PMDC motor 1 by a second screw 14. Additionally, the pump housing 9 is also provided with a fixing hole 10 for connecting external devices.

[0043] This embodiment is equipped with two sealing rings, which can increase the sealing performance of the liquid pump 2 to prevent liquid from penetrating into the PMDC motor.

[0044] For example Figure 3 , Figure 4 and Figure 5 As shown, in this embodiment, the upper cover 3 includes a plane 44 connecting the pump housing 9, an inlet 23 provided on the plane 44 for liquid circulation, a main outlet 22 provided on the plane 44 for liquid circulation, a ring post 31 extending vertically upward from the plane 44, and a first through hole 29 penetrating the plane 44 and the ring post 31 and coaxial with the upper cover 3.

[0045] An outlet wall 26 covering the main outlet 22 is provided in the annular space 30 between the outer wall of the first through hole 29 and the inner wall of the dial indicator 31. The two ends of the outlet wall 26 are connected to the inlet 23, and the middle is an arched curved surface 33. An outlet 27 for liquid circulation is provided on the outer wall of the dial indicator 31, adjacent to the outlet wall 26. A first groove 32 for engaging the first sealing ring 17 is also provided on the outer wall of the dial indicator 31.

[0046] The upper cover 3 is also provided with reinforcing ribs 28 to increase the strength of the upper cover 3 and facilitate the high-speed circulation of liquid in and out of the upper cover 3.

[0047] In this embodiment, the pump housing 9 includes a contact surface 43 connected to the upper cover 3, a first annular groove 40, a second annular groove 41 and a third annular groove 42 coaxial with the contact surface 43, a groove 6, a threaded hole 8, a positioning hole 18 and a positioning post 19 connected to the positioning hole 18 provided on the contact surface 43, and a second slot 34 provided on the outer wall of the pump housing 9 for engaging the second sealing ring 16.

[0048] In addition to the connection between the pump housing 9 and the upper cover 3 via the threaded hole 8 and the first screw 24, they are also connected via the positioning hole 18 and the positioning pin 19. This further increases the tightness of the connection between the contact surface 43 of the pump housing 9 and the plane 44 of the upper cover 3, preventing liquid from entering the PMDC motor through gaps. Simultaneously, a positioning wall 25 is provided on the upper cover 3 at a position corresponding to the positioning pin 19 to further strengthen the upper cover 3.

[0049] The external gear rotor 5 and the internal gear rotor 4 are placed in the groove 6. Specifically, the internal gear rotor 4 is placed in the gear hole 20 of the external gear rotor 5, and then the internal gear rotor 4 and the external gear rotor 5 are placed together in the groove 6. In addition, the groove 6 is also provided with a shallow groove-shaped flow channel 7 that matches the shape of the inlet 23 and the main outlet 22 to improve pump efficiency and hydraulic pulsation.

[0050] Because the internal gear rotor 4 and the external gear rotor 5 are eccentrically connected, and the internal gear rotor 4 is driven to rotate by the drive shaft 12, during rotation, the liquid from the external system can enter the gap between the internal gear rotor 4 and the external gear rotor 5 through the inlet 23. When the gap coincides with the main outlet 22, the liquid flows out from the main outlet 22 and then flows to the outside of the liquid pump 2 via the outlet 27. The bottom surface of the first annular groove 40 is provided with a second through hole 35 that is coaxial with the first annular groove 40 and penetrates the pump housing 9. The shaft seal 11 is placed on the first annular groove 40. The drive shaft 12 of the PMDC motor 1 passes through the shaft seal 11 and the second through hole 35, and then engages with the bayonet 21 of the internal gear rotor 4 through the double flat structure 13 at the top. The bottom surface of the third annular groove 42 is provided with a connection hole 36 for connecting the PMDC motor 1 and a fixing hole 10 for connecting the external system. The second annular groove 41 is located between the first annular groove 40 and the third annular groove 42. It is used to engage the front end face 39 of the PMDC motor 1, which can further improve the stability when the PMDC motor drives the liquid pump to rotate at high speed, thereby preventing liquid from penetrating into the interior of the PMDC motor.

[0051] In this embodiment, the shaft seal 11 includes an annular concave ring 37 and a spring 15 that is engaged with the inner wall of the concave ring 37. The concave ring 37 can be made of an elastic material, which can tightly wrap the drive shaft 12. The elastic force of the intermediate spring 15 can further improve the sealing performance, so that even when the drive shaft 12 rotates at high speed, liquid will still not penetrate into the interior of the PMDC motor.

[0052] The liquid pump 2 in this embodiment of the invention can be a pump for pumping coolant and / or lubricant, such as water or oil, or it can be a pump for pumping other liquids; the invention does not specifically limit this. When used in the cooling system and / or lubrication system of an engine, the liquid pump 2 is a pump for pumping oil.

[0053] The pump housing 9, top cover 3, internal gear rotor 4, and external gear rotor 5 described in the above embodiments can be made of metal or plastic, such as PPS (polyphenylene sulfide), PA6 (nylon 6), PA66 (nylon-66 or polyamide-66), etc. The materials of the aforementioned components can be the same or different. Preferably, when the pump housing 9, top cover 3, internal gear rotor 4, and external gear rotor 5 are all made of plastic, the weight of the liquid pump 2 can be greatly reduced, and the cost can also be significantly lowered.

[0054] For example Figure 6 As shown, the motor control system of this embodiment includes a ripple current detection unit for detecting the ripple current of a PMDC motor, and a pulse width modulation unit connecting the ripple current detection unit and the PMDC motor.

[0055] Specifically, the pulse width modulation unit gradually increases the input power of the PMDC motor from low to high through pulse width modulation; and receives the ripple current value of the PMDC motor sent by the ripple current detection unit, and stops increasing the input power when the ripple current value of the PMDC motor reaches a preset limit value.

[0056] The ripple current detection unit detects the ripple current value generated when the PMDC motor starts in real time and feeds it back to the pulse width modulation unit.

[0057] Furthermore, in one embodiment, the pulse width modulation unit further includes determining whether the ripple current value is abnormal, and if so, stopping the increase of input power.

[0058] In another embodiment, the pulse width modulation unit is connected to an external pulse width control system and adjusts the input power accordingly based on the control of the external pulse width control system. When the pulse width modulation unit detects an abnormal ripple current value, it feeds back the abnormal information to the external pulse width control system.

[0059] Specifically, the input power of the PMDC motor can be gradually increased in increments of 50W, 65W, and 70W through the pulse width modulation unit. This method of cold-starting the PMDC motor can avoid the excessive current caused by stalling due to low temperature cold start, which could burn out the motor's related auxiliary circuit equipment and pose other safety hazards, thus effectively extending the service life of the equipment.

[0060] During the cold start of a PMDC motor, real-time monitoring of the PMDC motor's ripple current value can provide early warning of abnormal starting conditions and avoid potential safety hazards.

[0061] For example Figure 7 As shown, the motor control method of this invention, used to control a PMDC motor, includes the following steps:

[0062] S1. The input power of the PMDC motor is gradually increased from low to high through pulse width modulation, and the ripple current value generated when the PMDC motor starts is detected in real time.

[0063] S2. When the ripple current value of the PMDC motor reaches the preset limit, stop increasing the input power.

[0064] In one embodiment, step S2 further includes: determining whether the ripple current value is abnormal; if so, stopping the increase of input power.

[0065] In another embodiment, step S1 further includes: adjusting the input power according to the control response of the external pulse width control system. Step S2 further includes: when an abnormal ripple current value is detected, feeding back abnormal information to the external pulse width control system.

[0066] In summary, the liquid pump of this invention can be driven by a PMDC motor, and through multiple sealing designs, it can effectively prevent liquid from entering the PMDC motor. It can be applied to various cooling and lubrication systems. At the same time, by gradually increasing the input power, the PMDC motor is controlled to enter a cold start mode with low power, low current, and low voltage, which can effectively avoid safety hazards and extend the service life of the equipment.

[0067] The above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, such as combining different features in various embodiments, and these all fall within the protection scope of the present invention.

Claims

1. A liquid pump driven by a PMDC motor, characterized by, The pump comprises a pump shell for connecting a PMDC motor, an upper cover connected to the pump shell and provided with openings for liquid circulation, a shaft seal for sleeving a driving shaft of the PMDC motor and being arranged in the pump shell, an internal gear rotor arranged in the pump shell and for connecting the driving shaft, an external gear rotor eccentrically sleeved with the internal gear rotor, and a first sealing ring and a second sealing ring respectively clamped on the upper cover and the pump shell.

2. The liquid pump driven by a PMDC motor as defined in claim 1, wherein, The upper cover comprises a plane connected to the pump shell, an inlet arranged on the plane for liquid circulation, a main outlet arranged on the plane for liquid circulation, a loop column vertically extending from the plane, and a first through hole penetrating the plane and the loop column and coaxial with the upper cover; An outlet wall covering the main outlet is arranged in an annular space between the outer wall of the first through hole and the inner wall of the loop column; A side of the outer wall of the loop column adjacent to the outlet wall is provided with a secondary outlet for liquid circulation, and the outer wall of the loop column is further provided with a first clamping groove clamping the first sealing ring.

3. The liquid pump driven by a PMDC motor as defined in claim 2, wherein, Two ends of the outlet wall are connected with the inlet, and the middle is an arched curved surface.

4. The liquid pump driven by a PMDC motor according to claim 1, wherein, The pump shell comprises a contact surface connected to the upper cover, a first annular groove, a second annular groove and a third annular groove coaxial with the contact surface, a groove, a threaded hole, a positioning hole and a positioning column connected to the positioning hole arranged on the contact surface, and a second clamping groove arranged on the outer wall of the pump shell and clamping the second sealing ring; A second through hole penetrating the pump shell is arranged on the bottom surface of the first annular groove, and the shaft seal is arranged on the first annular groove; The bottom surface of the third annular groove is provided with a connecting hole for connecting the PMDC motor, and a fixing hole for connecting an external system.

5. The liquid pump driven by a PMDC motor as defined in claim 4, wherein, The second annular groove is located between the first annular groove and the third annular groove, and clamps the front end surface of the PMDC motor.

6. The liquid pump driven by a PMDC motor as defined in claim 4, wherein, The external gear rotor and the internal gear rotor are arranged in the groove.

7. The liquid pump driven by a PMDC motor as defined in claim 4, wherein, The groove is provided with a shallow groove-shaped flow channel consistent in shape with the inlet and the main outlet.

8. The liquid pump driven by a PMDC motor as defined in claim 1, wherein, The shaft seal comprises a circular annular groove, and a spring clamped on the inner wall of the groove.

9. An electric motor control system characterized by, The pump further comprises a ripple current detection unit for detecting the ripple current of the PMDC motor, and a pulse width modulation unit connected to the ripple current detection unit and the PMDC motor. The pulse width modulation unit gradually increases the input power of the PMDC motor from low to high through pulse width modulation, and receives the ripple current value of the PMDC motor sent by the ripple current detection unit, and stops increasing the input power when the ripple current value of the PMDC motor reaches a preset limit value. The ripple current detection unit detects the ripple current value generated when the PMDC motor starts in real time and feeds back to the pulse width modulation unit.

10. The motor control system of claim 9, wherein, The pulse width modulation unit judges whether the ripple current value is abnormal, and if so, stops increasing the input power.

11. The motor control system of claim 9, wherein, The pulse width modulation unit is connected with an external pulse width control system, and adjusts the input power according to the control of the external pulse width control system.

12. The motor control system of claim 11, wherein, When the pulse width modulation unit finds that the ripple current value is abnormal, it feeds back abnormal information to the external pulse width control system.

13. A method of controlling an electric machine, characterized by A method for controlling a PMDC motor as claimed in any one of claims 1 to 8, comprising the following steps: S1. gradually increasing the input power of the PMDC motor from low to high by pulse width modulation, and detecting the ripple current value generated when the PMDC motor starts in real time; S2. stopping increasing the input power when the ripple current value of the PMDC motor reaches a preset limit value.

14. The motor control method of claim 13, wherein, The step S2 further comprises: judging whether the ripple current value is abnormal, and if so, stopping increasing the input power.

15. The motor control method of claim 13, wherein, The step S1 further comprises: adjusting the input power according to the control of an external pulse width control system.

16. The motor control method of claim 15, wherein, The step S2 further comprises: when the pulse width modulation unit finds that the ripple current value is abnormal, feeding back abnormal information to the external pulse width control system.

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