A magnetic field switching liquid-cooled retarder system

Abstract

This invention discloses a magnetic field switching liquid-cooled retarder system, belonging to the field of automotive auxiliary braking technology. The system includes a retarder, a contact switch device, a control module, and an on-board battery. The retarder includes a stator, a rotor, an excitation coil, and a liquid cooling system. Two rings of stator salient poles are arranged on the side of the stator closest to the rotor, with each ring of salient poles evenly distributed circumferentially. The rotor has a cylindrical structure and is connected to the vehicle's drive shaft via splines. The excitation coil is wound around the stator salient poles, with the left and right excitation coils connected in series alternately, and adjacent excitation coils wound in opposite directions. The control module changes the current path in the excitation coil by controlling the on / off combinations of the contact switch device, causing the retarder to form a circumferential N-S alternating magnetic field at low speeds and an axial closed magnetic field at high speeds. The rotor cuts the air gap magnetic field to generate eddy currents and form braking torque, and the braking heat is carried away by the circulating coolant. This invention has a compact structure and can achieve both low-speed and high-speed braking performance.

Description

Technical Field

[0001] This invention belongs to the field of automotive auxiliary braking technology, specifically relating to a magnetic field switching liquid-cooled retarder system. Background Technology

[0002] Retarder is a commonly used auxiliary braking device in the transmission systems of commercial vehicles, primarily used in conditions such as long downhill slopes, frequent braking, or heavy-load operation. Its function is to convert some of the vehicle's kinetic energy into heat energy and dissipate it promptly without relying on the main brake friction pair, thereby reducing the load on the service brakes, lowering the risk of brake temperature rise and fade, and improving vehicle driving safety. Currently, the most commonly used retarders in vehicles include hydraulic retarders and eddy current retarders.

[0003] Eddy current retarders offer advantages such as fast response, relatively simple structure, and no mechanical contact wear, making them suitable for applications in buses, freight cars, and engineering vehicles. Based on the different forms of magnetic field action, traditional eddy current retarders can be divided into alternating magnetic field braking type and pulsating magnetic field braking type. Alternating magnetic field braking type eddy current retarders typically form an alternating polarity air gap magnetic field through adjacent circumferential excitation poles. When the rotor rotates, it cuts this magnetic field and generates eddy currents. Because this type of magnetic field changes rapidly with rotor motion, it can generate a large eddy current density and braking torque in the low-speed range, resulting in good low-speed braking performance. However, under high-speed conditions, the rotor is easily affected by the skin effect, reducing the effective eddy current distribution and significantly decreasing the braking torque.

[0004] The magnetic field direction of the pulsating magnetic field braking eddy current retarder is relatively stable, while the air gap magnetic field mainly exhibits changes in magnitude. Compared with alternating magnetic field braking, its magnetic field change rate is smaller at low speeds, resulting in relatively insufficient braking torque; however, it is less affected by the skin effect at high speeds, maintaining good high-speed braking capability. Therefore, alternating magnetic field braking and pulsating magnetic field braking each have their advantages across different vehicle speed ranges, and their braking characteristics are somewhat complementary.

[0005] Due to limited installation space in existing vehicles, simultaneously installing two different types of eddy current retarders would not only increase the overall vehicle layout difficulty and manufacturing costs but also complicate the transmission system structure, hindering practical application. Conversely, using only a single magnetic field type retarder would struggle to simultaneously achieve both high braking torque at low speeds and stable braking performance at high speeds. Furthermore, eddy current retarders generate significant heat during continuous braking; insufficient heat dissipation would negatively impact their continuous braking effect and operational stability.

[0006] For example, patent CN201570971U discloses an eddy current retarder. This design features multiple pairs of excitation coils evenly distributed on the circumference of the stator, with adjacent magnetic poles having opposite polarities. The rotating drum assembly rotates with the drive shaft and cuts the magnetic field to generate eddy current braking torque. Simultaneously, heat dissipation blades are installed on the outer circumference of the drum for heat dissipation. This structure can achieve conventional eddy current braking and is relatively simple. However, the magnetic field form of its excitation coils is relatively fixed, and the energizing path of the excitation coils cannot be changed according to vehicle speed. Furthermore, it cannot switch between the circumferential alternating NS magnetic field and the axial closed magnetic field within the same retarder. Additionally, relying solely on external heat dissipation blades for heat dissipation still results in insufficient heat dissipation capacity under long downhill slopes or continuous braking conditions.

[0007] Therefore, it is necessary to design a compact and easy-to-install magnetic field switching liquid-cooled retarder system. By controlling the contact switch device to change the current path of the excitation coil, the retarder can form a circumferential N-S alternating magnetic field at low speeds and an axial closed magnetic field at high speeds, thereby taking into account the braking performance at different vehicle speeds and using liquid cooling to improve continuous braking capability. Summary of the Invention

[0008] The technical problem solved by this invention: This invention aims to overcome the problems of existing eddy current retarders being unable to simultaneously handle high power and thermal decay across the entire speed range, and to provide a liquid-cooled retarder system that can automatically switch the excitation magnetic field according to operating conditions.

[0009] The present invention is achieved through the following scheme: a magnetic field switching liquid-cooled retarder system, including a retarder, a contact switch device 8, a control module 11, and a battery 12. The retarder includes a stator 2, a rotor 3, an excitation coil 6, and a liquid cooling system. The stator 2 has two rows of stator salient poles arranged side by side evenly in the circumferential direction, and an excitation coil 6 is wound on each stator salient pole.

[0010] The positive and negative terminals of the battery 12 are connected to the positive and negative terminals of the control module 11 via circuits. The positive terminal of the control module 11 is connected to one end of normally open contact SB1, one end of normally open contact SB3, and one end of normally open contact SB2 in the contact switch device 8. The other end of normally open contact SB1 is connected to the input terminal of the excitation coil 6 on the first stator salient pole on the left. The other end of normally open contact SB3 is connected to the input terminal of the excitation coil 6 on the first stator salient pole on the right and one end of normally open contact SB4. The other end of normally open contact SB4 and one end of normally open contact SB5 are connected to the negative terminal of the control module 11. The other ends of normally open contact SB2 and normally open contact SB5 are connected to the output terminal of the excitation coil 6 on the last stator salient pole on the right. The output terminal of the excitation coil 6 on the last stator salient pole on the left is connected to the negative terminal of the control module 11.

[0011] The excitation coil 6 on the left stator salient pole and the excitation coil 6 on the right stator salient pole are connected in series alternately in sequence.

[0012] The control module 11 controls the switching state of each contact switch in the contact switch device 8 through the signal line 9 of the contact switch device, and can also adjust the current in the excitation coil 6.

[0013] Preferably, the normally open contacts in the contact switch device 8 can be relays or insulated gate field-effect transistors, and the control module 11 can close or open them by applying a positive voltage to their signal terminals.

[0014] Preferably, the control module 11 is connected to the battery via a wiring connection, the vehicle battery 12 is fixed to the vehicle frame, and the retarder is fixed to the rear end of the transmission.

[0015] Preferably, the rotor 3 has a groove structure in the middle to prevent magnetic leakage when the axial closed magnetic field is in a state of flux leakage.

[0016] Preferably, the gap between the stator salient pole and the outer ring of the rotor 3 is 0.5~1mm.

[0017] Preferably, the stator 2 is provided with a liquid inlet 1 and a liquid outlet 7. The coolant enters through the liquid inlet 1, then cools the rotor, and finally returns to the condenser through the liquid outlet 7.

[0018] Preferably, the control method for the magnetic field switching liquid-cooled retarder system includes the following steps: When the vehicle brakes: Step 1: When the control module detects that the speed V of the car drive shaft is equal to the set speed V0, the control module controls normally open contact 3 (SB3), normally open contact 5 (SB5), and normally open contact 1 (SB1) to close, and normally open contact 2 (SB2) and normally open contact 4 (SB4) to open, so that the excitation coil on the left stator salient pole and the excitation coil on the right stator salient pole form an alternating magnetic field with axial magnetic flux NS. At this time, the retarder realizes alternating magnetic field braking suitable for low speed. Step 2: When the speed of the car drive shaft is greater than the set speed V0, the control module controls normally open contacts SB3 and SB5 to open, and normally open contacts SB1, SB2, and SB4 to close, so that the excitation coil 6 on the left stator salient pole and the excitation coil 6 on the right stator salient pole form an axially closed magnetic field. At this time, the retarder realizes pulsating magnetic field braking suitable for high speed.

[0019] When the vehicle is not braking: the control module controls normally open contacts SB1, SB2, SB3, SB4, and SB5 to all open.

[0020] In addition, to prevent interruption of braking torque during magnetic field switching, when braking is required, if the detected speed of the vehicle's drive shaft 4 is greater than V0, the magnetic field will not switch as the vehicle speed decreases. Each time the retarder is activated for braking, the detected vehicle speed determines the braking method, and this determination will remain unchanged until the next activation of the retarder.

[0021] Preferably, the driver adjusts the excitation current of the excitation coil 6 according to the road condition control module 11 to control the braking torque of the magnetic field switching liquid-cooled retarder.

[0022] The main advantages of the magnetic field switching liquid-cooled retarder system of the present invention are as follows: The technical solution of the present invention has a compact structure. Two rows of salient poles are evenly arranged in the circumferential direction of the stator 2 of the retarder. The excitation coil 6 is fixed on the salient poles of the stator. Based on the above structure, according to the vehicle speed, the control module 11 realizes the change of the direction of the magnetic field part by controlling the contact switch device 8, thereby improving the braking performance. The stator 2 is provided with a liquid inlet 1 and a liquid outlet 7. The coolant enters through the liquid inlet, then cools the rotor 3, and finally returns to the condenser for heat dissipation through the liquid outlet. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of a magnetic field switching liquid-cooled retarder system according to the present invention; Figure 2 This is a front view of a magnetic field switching liquid-cooled retarder system according to the present invention; Figure 3 This invention relates to a three-dimensional stator of a magnetic field switching liquid-cooled retarder system. Figure 1 ; Figure 4 This invention relates to a three-dimensional rotor of a magnetic field switching liquid-cooled retarder system. Figure 2 ; Figure 5 This is a magnetic field distribution diagram of a magnetic field switching liquid-cooled retarder system of the present invention when operating at low speed. Figure 6 This is a magnetic field distribution diagram of a magnetic field switching liquid-cooled retarder system of the present invention during high-speed operation; Figure 7 This is a schematic diagram of the excitation coil wiring principle of a magnetic field switching liquid-cooled retarder system according to the present invention; Reference numerals: 1-Inlet, 2-Stator, 3-Rotor, 4-Drive shaft, 5-Stator end cover, 6-Excitation coil, 7-Outlet, 8-Contact switch device, 9-Control signal line, 10-Switching power supply line, 11-Control module, 12-On-board battery, S-Magnetic circuit schematic line. Detailed Implementation

[0024] The following is in conjunction with the appendix Figure 1-7 Further details on specific embodiments of the present invention are provided below. A magnetic field switching liquid-cooled retarder system of the present invention includes a retarder, a contact switch device 8, a control module 11, and an on-board battery 12. The retarder includes a stator 2, a rotor 3, an excitation coil 6, and a liquid cooling system. The stator 2 is a fixedly arranged annular structure. The rotor 3 is coaxially arranged inside the stator 2 and is a cylindrical structure, connected to the vehicle drive shaft 4 via a spline, and can rotate synchronously with the vehicle drive shaft 4. Two rings of stator salient poles, left and right, are arranged axially on the side of the stator 2 closest to the rotor 3. Each ring of stator salient poles is evenly distributed along the circumference of the stator 2, and the left and right rings of stator salient poles are arranged correspondingly to each other. Each stator salient pole is wound with an excitation coil 6. The excitation coil 6 on the left stator salient pole and the excitation coil 6 on the right stator salient pole are connected in series alternately in sequence, with adjacent connected excitation coils 6 wound in opposite directions. An air gap is formed between the inner end of the stator salient pole and the outer wall of the rotor 3. When the excitation coil 6 is energized, a magnetic field is generated in this air gap. The control module 11 controls the direction of current flow in the excitation coil 6 through the contact switch device 8 to change the closed path of the magnetic field inside the retarder, thereby realizing the switching of different braking modes.

[0025] The contact switch device 8 includes normally open contact SB1, normally open contact SB2, normally open contact SB3, normally open contact SB4, normally open contact SB5, control signal line 9, and switching power supply line 10. The normally open contacts can be relay contacts or switch branches formed by insulated gate field-effect transistors. The control module 11 outputs control signals to the control terminals of the corresponding contacts or switch branches through the control signal line 9, causing them to close or open.

[0026] The positive and negative terminals of the vehicle battery 12 are connected to the positive and negative terminals of the control module 11 via circuits, respectively. The positive terminal of the control module 11 is connected to one end of normally open contact SB1, one end of normally open contact SB2, and one end of normally open contact SB3; the other end of normally open contact SB1 is connected to the input terminal of the excitation coil 6 on the left first stator salient pole; the other end of normally open contact SB3 is connected to the input terminal of the excitation coil 6 on the right first stator salient pole and one end of normally open contact SB4; the other ends of normally open contact SB4 and normally open contact SB5 are both connected to the negative terminal of the control module 11; the other ends of normally open contact SB2 and normally open contact SB5 are both connected to the output terminal of the excitation coil 6 on the right last stator salient pole; and the output terminal of the excitation coil 6 on the left last stator salient pole is connected to the negative terminal of the control module 11.

[0027] The excitation coil 6 on the left stator salient pole and the excitation coil 6 on the right stator salient pole are connected in series alternately in sequence, and the winding directions of adjacent excitation coils 6 are opposite. The control module 11 controls the on / off state of each normally open contact in the contact switch device 8 through the control signal line 9, thereby changing the current flow direction in the excitation coil 6, and the braking torque of the retarder can be adjusted by adjusting the magnitude of the excitation current in the excitation coil 6.

[0028] The rotor 3 has a groove structure in the middle to reduce magnetic leakage under axial closed magnetic field conditions. The control module 11 detects the speed of the vehicle drive shaft 4 and controls the on / off state of the contact switch device 8 according to the vehicle speed. When the vehicle speed is low, the control module 11 causes the excitation coil 6 to form a circumferential N-S alternating magnetic field inside the retarder, such as... Figure 5 As shown, S is a schematic line of the magnetic circuit, used to represent the circumferential NS alternating magnetic flux closed path formed between the stator salient pole, the air gap, and the outer peripheral surface of the rotor 3 after the excitation coil 6 is energized under low-speed conditions. S does not represent a separate structural component. When the vehicle speed is higher, the control module 11 causes the excitation coil 6 to form an axial closed magnetic field inside the retarder. Both of the above magnetic fields can form an air gap magnetic field between the inner end of the stator salient pole and the outer peripheral surface of the rotor 3. When the rotor 3 rotates with the vehicle drive shaft 4, it cuts the air gap magnetic field, generating eddy currents in the rotor 3, thereby forming an eddy current braking torque.

[0029] The control module 11 is connected to the vehicle battery 12 via wiring. The vehicle battery 12 is fixed to the vehicle frame, and the retarder is fixed to the rear end of the transmission. The stator 2 is provided with a liquid inlet 1 and a liquid outlet 7. The coolant enters the retarder through the liquid inlet 1, cools the rotor 3 and surrounding heat-generating components, and then flows out through the liquid outlet 7 and returns to the condenser for heat dissipation. An air gap is formed between the inner end of the stator salient pole and the outer peripheral surface of the rotor 3, and the width of the air gap is 0.5 to 1 mm.

[0030] The present invention provides a control method for a magnetic field switching liquid-cooled retarder system, comprising the following steps: When the vehicle brakes, the control module 11 detects the speed V of the vehicle drive shaft 4 and compares it with the set speed V0.

[0031] When the speed V of the vehicle drive shaft 4 is less than or equal to the set speed V0, the control module 11 controls normally open contacts SB1, SB3, and SB5 to close, and normally open contacts SB2 and SB4 to open, so that the excitation coils 6 on the left and right stator salient poles form a circumferential alternating magnetic field NS. At this time, the rotor 3 rotates with the vehicle drive shaft 4 and cuts the air gap magnetic field, generating eddy currents in the rotor 3, thereby forming an eddy current braking torque suitable for low-speed conditions.

[0032] When the speed V of the vehicle drive shaft 4 is greater than the set speed V0, the control module 11 controls normally open contacts SB1, SB2, and SB4 to close, and normally open contacts SB3 and SB5 to open, so that the excitation coils 6 on the left and right stator salient poles form an axial closed magnetic field. At this time, the rotor 3 cuts the axial closed magnetic field to form eddy currents, thereby generating an eddy current braking torque suitable for high-speed operation.

[0033] When the vehicle is not braking, the control module 11 controls the normally open contacts SB1, SB2, SB3, SB4, and SB5 to open, the excitation coil 6 is not energized, and the retarder does not generate braking torque.

[0034] To avoid a brief interruption of braking torque due to magnetic field mode switching during braking, the control module 11 determines the braking mode based on the currently detected speed V of the vehicle's drive shaft 4 each time the retarder braking is initiated. During this braking process, the determined braking mode remains unchanged until the retarder braking ends; the next time the retarder braking is initiated, the control module 11 re-determines the mode based on the vehicle speed.

[0035] The driver can adjust the excitation current in the excitation coil 6 through the control module 11 according to the road conditions, thereby controlling the braking torque of the magnetic field switching liquid-cooled retarder.

Claims

1. A magnetic field switching type liquid-cooled retarder system, comprising a retarder, a contact switch device (8), a control module (11), and an on-board battery (12), wherein the retarder comprises a stator (2), a rotor (3), an excitation coil (6), and a liquid cooling system, characterized in that: The stator (2) is a fixed ring structure, and the rotor (3) is coaxially arranged inside the stator (2). The rotor (3) is a cylindrical structure and is connected to the car drive shaft (4) by a spline. The stator (2) has two rings of stator salient poles on the side close to the rotor (3) along the axial direction. Each ring of stator salient poles is evenly distributed along the circumference of the stator (2), and the left and right rings of stator salient poles are arranged corresponding to each other. Each stator salient pole is wound with an excitation coil (6). The excitation coil (6) on the left stator salient pole and the excitation coil (6) on the right stator salient pole are connected in series alternately in sequence. The adjacent excitation coils (6) are wound in opposite directions. The control module (11) is electrically connected to the contact switch device (8), which is connected to the energizing circuit of the excitation coil (6). The control module (11) controls the on / off combination of each normally open contact in the contact switch device (8) to make the excitation coil (6) on the left stator salient pole and the excitation coil (6) on the right stator salient pole form different energizing paths, thereby changing the current flow direction in the excitation coil (6) and the magnetic pole matching relationship between adjacent excitation coils (6), so that the retarder can form a circumferential NS alternating magnetic field or an axial closed magnetic field to achieve eddy current braking under different magnetic field closed paths.

2. The magnetic field switching liquid-cooled retarder system according to claim 1, characterized in that: The contact switch device (8) includes normally open contact 1 (SB1), normally open contact 2 (SB2), normally open contact 3 (SB3), normally open contact 4 (SB4), and normally open contact 5 (SB5); the positive and negative terminals of the vehicle battery (12) are connected to the positive and negative terminals of the control module (11), respectively; the positive terminal of the control module (11) is connected to one end of normally open contact 1 (SB1), one end of normally open contact 2 (SB2), and one end of normally open contact 3 (SB3), respectively; the other end of normally open contact 1 (SB1) is connected to the input terminal of the excitation coil (6) on the left first stator salient pole. The other end of normally open contact 3 (SB3) is connected to the input terminal of the excitation coil (6) on the first stator salient pole on the right and one end of normally open contact 4 (SB4). The other end of normally open contact 4 (SB4) and one end of normally open contact 5 (SB5) are both connected to the negative terminal of the control module (11). The other end of normally open contact 2 (SB2) and the other end of normally open contact 5 (SB5) are both connected to the output terminal of the excitation coil (6) on the last stator salient pole on the right. The output terminal of the excitation coil (6) on the last stator salient pole on the left is connected to the negative terminal of the control module (11).

3. The magnetic field switching liquid-cooled retarder system according to claim 2, characterized in that: The control module (11) changes the energizing path of the excitation coil (6) by controlling the on / off combination of normally open contact 1 (SB1), normally open contact 2 (SB2), normally open contact 3 (SB3), normally open contact 4 (SB4) and normally open contact 5 (SB5); when normally open contact 1 (SB1), normally open contact 3 (SB3) and normally open contact 5 (SB5) are connected, and normally open contact 2 (SB2) and normally open contact 4 (SB4) are disconnected, the excitation coil (6) forms a circumferential NS alternating magnetic field inside the retarder; when normally open contact 1 (SB1), normally open contact 2 (SB2) and normally open contact 4 (SB4) are connected, and normally open contact 3 (SB3) and normally open contact 5 (SB5) are disconnected, the excitation coil (6) forms an axial closed magnetic field inside the retarder.

4. The magnetic field switching liquid-cooled retarder system according to claim 3, characterized in that: The control module (11) is used to detect the speed of the car drive shaft (4) and select the on / off state of the contact switch device (8) according to the detected speed; when the speed of the car drive shaft (4) is less than or equal to the set speed, the retarder works in the circumferential NS alternating magnetic field braking state; when the speed of the car drive shaft (4) is greater than the set speed, the retarder works in the axial closed magnetic field braking state.

5. The magnetic field switching liquid-cooled retarder system according to any one of claims 1-4, characterized in that: The rotor (3) has a groove structure in the middle, which is used to reduce magnetic leakage under axial closed magnetic field conditions.

6. The magnetic field switching liquid-cooled retarder system according to any one of claims 1-4, characterized in that: An air gap is formed between the inner end of the stator salient pole and the outer peripheral surface of the rotor (3). The width of the air gap is 0.5 to 1 mm. When the rotor (3) rotates, it cuts the magnetic field in the air gap and generates eddy currents.

7. The magnetic field switching liquid-cooled retarder system according to any one of claims 1-4, characterized in that: The stator (2) is provided with an inlet (1) and an outlet (7). The coolant enters the retarder through the inlet (1), cools the rotor (3) and surrounding heat-generating components, and then flows out through the outlet (7) and returns to the condenser to dissipate heat.

8. The magnetic field switching liquid-cooled retarder system according to any one of claims 1-4, characterized in that: The control module (11) is connected to the vehicle battery (12) via a line. The vehicle battery (12) is fixed on the vehicle frame, and the retarder is fixed at the rear end of the transmission.

9. A control method for a magnetic field switching liquid-cooled retarder system according to claim 4, characterized in that, Includes the following steps: When the vehicle brakes, the control module (11) detects the speed V of the vehicle drive shaft (4) and compares it with the set speed V0; When V is less than or equal to V0, the control module (11) controls normally open contact one (SB1), normally open contact three (SB3) and normally open contact five (SB5) to be connected, and controls normally open contact two (SB2) and normally open contact four (SB4) to be disconnected, so that the excitation coil (6) forms a circumferential NS alternating magnetic field inside the retarder; When V is greater than V0, the control module (11) controls normally open contact one (SB1), normally open contact two (SB2) and normally open contact four (SB4) to be connected, and controls normally open contact three (SB3) and normally open contact five (SB5) to be disconnected, so that the excitation coil (6) forms an axial closed magnetic field inside the retarder; When the vehicle is not braking, the control module (11) controls normally open contact one (SB1), normally open contact two (SB2), normally open contact three (SB3), normally open contact four (SB4) and normally open contact five (SB5) to be disconnected, so that the excitation coil (6) is not energized.

10. The control method according to claim 9, characterized in that: Each time the retarder braking is initiated, the control module (11) determines the braking state based on the speed V of the currently detected vehicle drive shaft (4); during this braking process, the determined braking state remains unchanged until the current retarding braking ends; the driver can adjust the magnitude of the excitation current in the excitation coil (6) through the control module (11) to adjust the braking torque of the magnetic field switching liquid-cooled retarder.

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