Automobile starter and its electromagnetic switch

Abstract

Provided are an automobile starter and an electromagnetic switch thereof. The electromagnetic switch comprises a housing (105), a switch cover (110), terminals (109, 109a), a static iron core (106), a moving iron core (101), a first return spring (102), a second return spring (114), a moving contact (108) fixedly sleeved on a core shaft (112), a coil assembly comprising an attraction coil (104) and a holding coil (103) connected to each other, magnetic forces are superimposed at the initial stage of power on, and the circuit of the attraction coil (104) is disconnected after the moving iron core (101) moves a certain distance; a first static contact piece (107) and a second static contact piece (107a) which are insulated from the static iron core (106) and independent of each other are fixedly arranged on the upper end of the static iron core (106), one of which is electrically connected to one end of the attraction coil (104), and the other is electrically connected to the starter motor during operation; the problem of top teeth can be effectively solved and the volume of the electromagnetic switch can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile starter manufacturing, and in particular relates to an automobile starter and an electromagnetic switch thereof. Background Art

[0002] As we all know, the starting of the engine requires the support of external force, and the car starter plays this role. Generally speaking, the starter uses three components to realize the entire starting process. The DC series motor introduces current from the battery and causes the starter's drive gear to produce mechanical movement; the transmission mechanism meshes the drive gear into the flywheel ring gear, and can automatically disengage after the engine starts; the starter circuit is controlled by an electromagnetic switch. Before the engine runs with its own power, it must be rotated with the help of external force. The process of the engine transitioning from a static state to being able to run independently with the help of external force is called engine starting. There are three common starting methods for engines: manual starting, auxiliary gasoline engine starting, and electric starting. Manual starting uses rope pulling or hand cranking, which is simple but inconvenient, and has high labor intensity. It is only suitable for some low-power engines and is only retained as a backup method on some cars; auxiliary gasoline engine starting is mainly used on high-power diesel engines; the electric starting method is easy to operate, starts quickly, has the ability to start repeatedly, and can be controlled remotely, so it is widely used in modern cars.

[0003] The conventional flexible engagement starter structure of the prior art is as follows Figure 1 As shown, the starter generally includes a gear spring 1, a driving gear 2, a front cover 3, a check valve 4, a fork assembly 5, an electromagnetic switch 6, a relay 6A, a transmission reduction mechanism 7, a motor 8, etc.; wherein the electromagnetic switch 6 generally includes a moving iron core 9, a coil assembly 10, a return spring 11, a moving contact assembly 12, a switch cover 13, a terminal 14, etc. Figure 1As shown, after the relay 6A is energized and the contacts are closed, the electromagnetic switch 6 is energized through the contact action of the relay 6A, and the current enters the motor 8 from the coil assembly 10 to drive the motor 8 to rotate. The motor 8 drives the gear 2 through the transmission mechanism 7 and the one-way device 4 to generate slow rotation and a certain torque; at the same time, the current passing through the electromagnetic coil 10 causes the electromagnetic switch 6 to generate electromagnetic attraction, and the generated electromagnetic attraction causes the moving iron core 9 to move toward the switch cover 13. The iron core 9 pushes the moving contact assembly 12 to be mechanically and electrically connected with the terminal 14. At the same time, during the movement of the moving iron core 9, the one-way device 4 is toggled through the fork assembly 5, so that the driving gear The wheel 2 moves toward the direction of the engine flywheel gear ring 15; the slow-rotating driving gear 2 increases the probability of meshing with the flywheel gear ring 15, but when the tooth tip of the driving gear 2 just hits the tooth tip of the flywheel gear ring 15, the slow-rotating driving gear 2 cannot mesh with the flywheel gear ring 15 smoothly due to the small flexible meshing torque, and a "top tooth" phenomenon occurs; when the "top tooth" phenomenon occurs, the tooth head 2 must be rotated through an angle to stagger the top tooth state where the tooth tip of the driving gear 2 hits the tooth tip of the flywheel gear ring 15, and the driving gear 2 is inserted into the flywheel gear ring 15 under the action of the gear spring 1 and the return spring 11, thereby starting the engine.

[0004] In the prior art, the electromagnetic switch of the common flexible meshing starter, the coil assembly 10 is divided into two groups, the attraction coil and the holding coil, and the number of turns of the attraction coil and the number of turns of the holding coil must be basically the same; because the terminals of the attraction coil and the holding coil are connected together, when the starter is powered off, the attraction coil and the holding coil form a current closed loop with the battery through the action of the moving contact. If the number of turns of the attraction coil and the number of turns of the holding coil are basically the same, the electromagnetic attraction generated by the attraction coil and the electromagnetic attraction generated by the holding coil are basically the same because the number of turns of the two groups of coils is basically the same, and the current is the same in magnitude and opposite in direction, and the electromagnetic attraction The moving iron core 9 is offset, and the reaction force of the return spring 11 pushes it back to its initial position without the action of the electromagnetic attraction. The driving tooth head 2 is shifted back to its initial position by the action of the shift fork 5. On the contrary, if the number of turns of the attraction coil is inconsistent with the number of turns of the holding coil, the electromagnetic attraction generated by the attraction coil and the electromagnetic attraction generated by the holding coil are inconsistent with each other due to the inconsistency of the number of turns of the two sets of coils. The electromagnetic attraction will not be completely offset, and the moving iron core 9 cannot be smoothly pushed back to its initial position under the action of the reaction force of the return spring 11 under the action of the remaining electromagnetic attraction, and the starter will not be able to be powered off or will be unreliably powered off and burned out.

[0005] The electromagnetic switch needs to ensure that the electromagnetic attraction of the holding coil is sufficient so that the main contacts of the motor can be reliably connected to make the starter work. However, this process is very easy to achieve. However, it is not easy to make the starter drive tooth head rotate slowly and have a certain torque, that is, to achieve the purpose of flexible engagement starter. If the ordinary flexible engagement starter in the prior art wants to have sufficient electromagnetic attraction of the holding coil and flexible engagement function, there are two ways. The first way is to make the holding coil have more turns to ensure the electromagnetic attraction. At the same time, the number of turns of the attraction coil is basically the same as the number of turns of the holding coil, and the wire diameter of the attraction coil is increased to increase the current flowing into the motor, so that the motor produces slow rotation and has a certain torque; however, increasing the wire diameter of the attraction coil After that, the size of the electromagnetic switch will increase significantly. Therefore, this method cannot be used on small and medium power motors, but can only be used on high-power starters. Because the high-power starter is large in size, the size of the electromagnetic switch can also be made relatively large; the second method, reducing the number of turns of the holding coil and the attraction coil and increasing the coil wire diameter will also make the coil electromagnetic attraction sufficient, and the current flowing into the motor will increase relatively. The motor will also produce slow rotation and have a certain torque. However, the disadvantage of the second method is that the number of turns of the holding coil is small and the wire diameter is increased, the current flowing per unit time is relatively large, the temperature rise is too fast, and the electromagnetic switch will burn out after a short period of use. Therefore, the second method is not used on high-power starters and small and medium-power, and it is not a feasible solution.

[0006] In summary, the electromagnetic switch of the conventional flexible engagement starter can only be used on high-power starters, and is limited in use on medium and small power starters due to the increased size of the electromagnetic switch. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide an electromagnetic switch which can realize the function of flexible engagement starting on small and medium power starters without increasing the volume of the switch.

[0008] In order to solve the above technical problems, the basic scheme of the electromagnetic switch of the present invention is:

[0009] An electromagnetic switch for an automobile starter comprises a housing (105), a switch cover (110) fixedly connected to one end of the housing (105), a first terminal (109) and a second terminal (109a) fixedly arranged in the switch cover (110) and extending outwardly, a coil assembly arranged along the inner wall of the housing, a guide tube (113) arranged in the inner cavity formed by the housing (105) and the coil assembly, a static iron core (106) fixedly arranged on the inner side of the switch cover (110) and extending to the guide tube (113), a moving iron core (101) slidable along the guide tube (113) arranged at the inner end of the housing (105), the moving iron core (101) having an outer end extending outwardly for connecting to a shift fork assembly (5), a first reset spring (102) arranged between the static iron core (106) and the moving iron core (101); a core shaft (112) passing through a central hole of the static iron core, with both ends extending outwardly and being slidable; a moving contact (108) fixedly mounted On the core shaft (112), a second return spring (114) is arranged between the upper end of the moving contact (108) and the switch cover (110), and the lower end is opposite to the moving iron core (101); it is characterized in that a first static contact piece (107) and a second static contact piece (107a) are fixedly arranged independently of each other on the upper end of the static iron core (106), and the first static contact piece (107) and the second static contact piece (107a) are both insulated from the static iron core (106); the coil assembly comprises an attraction coil (104) and a holding coil (103) connected to each other, and the magnetic forces are superimposed when power is initially turned on, and the circuit of the attraction coil (104) is disconnected after the moving iron core (101) moves a certain distance; one of the first static contact piece (107) or the second static contact piece (107a) is electrically connected to one end of the attraction coil (104), and the other of the first static contact piece (107) or the second static contact piece (107a) is electrically connected to the starter motor part during operation.

[0010] The following is a further solution of the electromagnetic switch of the present invention:

[0011] The first stationary contact piece (107) and the second stationary contact piece (107a) are respectively fixed to the stationary iron core (106) by screws, and one end of the attraction coil (104) is welded to the stationary contact piece.

[0012] The first stationary contact piece (107) and the second stationary contact piece (107a) are insulated from the stationary iron core (106) by an insulating plate (111) sandwiched therebetween.

[0013] The first static contact piece (107) is connected to one end of the attraction coil (104), the second static contact piece (107a) is connected to one end of a conductive wire (116), one end of the holding coil 103 is connected to the static iron core 106, and the other ends of the holding coil 103, the attraction coil 104 and the conductive wire 116 are all led out from the switch cover.

[0014] The first static contact piece (107) is welded to one end of a short conductive wire (116), and the other end of the conductive wire (116) is led out from the switch cover (110). The second static contact piece (107a) is connected to one end of the attraction coil (104), and the other end of the attraction coil 104 is led out from the switch cover 110. One end of the holding coil 103 is connected to the static iron core 106, and the other end of the holding coil 103 is led out from the switch cover.

[0015] In the electromagnetic switch, the moving contact is arranged on a core shaft, and the core shaft is slidably arranged on the static iron core, one end of which is opposite to the moving iron core, and the other end is connected to the switch cover through a connecting piece (generally a spring), and the core shaft and the moving iron core are designed separately; when the motor is not powered on, the two static contact pieces are in a mechanical contact state with the moving contact. The coil assembly is divided into two groups, the attraction coil and the holding coil, wherein one end of the attraction coil assembly is connected to one of the two static contact pieces, and an electrical connection can be established when power is turned on. The remaining end of the attraction coil assembly is led out from the switch cover, one end of the holding coil assembly is connected to the switch power input terminal (an electrical connection can be established when power is turned on), and the other end of the holding coil assembly is connected to the static iron core, and an electrical connection can be established when power is turned on. In the electromagnetic switch, the other contact of the two static contact pieces that is not connected to the attraction coil assembly is connected to this contact with one end of a conductive wire, and an electrical connection can be established when power is turned on, and the other end of the conductive wire is led out from the switch cover.

[0016] In the electromagnetic switch, the shapes of the two static contact pieces are not particularly limited and can be changed to any shape according to installation requirements. The present invention further provides a flexible meshing starter equipped with the electromagnetic switch.

[0017] The automobile starter of the present invention is characterized in that it is provided with any electromagnetic switch as described above.

[0018] The beneficial effect of the present invention in solving the problem of not increasing the size of the switch is that: after the starter is energized, the current passes through the electromagnetic switch attraction coil group and the holding coil group at the same time, wherein the current flowing through the attraction coil group establishes an electrical connection state because the two static contacts and the moving contact are in a mechanical contact state, so the current flowing through the attraction coil group can enter the starter motor part, and the starter motor operates at low power. After the transmission reduction mechanism, the motor part provides the rotation speed and torque required by the drive gear; the slowly rotating drive gear increases the probability of the drive gear engaging with the flywheel gear ring, which is consistent with the function of the flexible engagement starter in ordinary technology. In addition, after the driving gear engages and enters the flywheel gear ring, the attraction coil will be in a disconnected state due to the departure of the moving contact, and only the holding coil group continues to be energized; when the engine is started, the power door lock is closed, the relay power-off contacts are disconnected, and the switch holding coil group is powered off (if the starter does not use a relay, the power door lock is closed and the switch holding coil group is powered off), the electromagnetic switch moving iron core is pushed back to the initial position by the reaction force of the return spring in the absence of electromagnetic suction, and the driving tooth head is shifted back to the initial position by the moving iron core through the action of the shift fork; because the power door lock is closed and the starter is powered off at the moment, the attraction coil is in a disconnected state, so a current closed loop cannot be formed between the battery and the attraction coil and the holding coil, and the power door lock is closed, the holding coil group is powered off, and the starter as a whole is powered off, so there is no problem of the influence of residual electromagnetic suction. Therefore, the beneficial effect of the present invention can make the number of turns of the holding coil group inconsistent with the number of turns of the attraction coil group, while ensuring that the electromagnetic suction of the holding coil group is sufficient In this case, the number of turns of the attraction coil group can be much less than the number of turns of the holding coil group. The reduced number of turns of the holding coil group reduces the resistance of the holding coil group. Due to the inverse relationship between current and resistance, the reduction in resistance increases the current flowing into the motor, causing the motor to rotate slowly and generate a certain torque. In addition, when the volume of the electromagnetic switch is constant, the reduction in the number of turns of the attraction coil provides remaining space for the electromagnetic switch. If the current flowing into the motor is not large enough, the slow rotation and torque of the motor are not large enough, the slow rotation speed and torque of the motor can be increased by increasing the wire diameter of the attraction coil or reducing the number of turns of the attraction coil (or increasing the wire diameter of the attraction coil and reducing the number of turns of the attraction coil at the same time), so as to achieve the purpose of flexible engagement. It can be seen that after the electromagnetic switch of the present invention adopts double static contacts, the starter can achieve the purpose of flexible engagement without changing the volume of the switch. Therefore, it can be applied to small and medium-power starters, so that small and medium-power starters can also achieve the same flexible engagement effect as high-power starters. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a structural diagram of a common flexible engagement starter in the prior art;

[0020] Figure 2 A structural diagram of a double-stationary contact electromagnetic switch according to an embodiment of the present invention;

[0021] Figure 3 for Figure 2 A plan view after removing the switch cover 110 and the terminals 109 and 109a;

[0022] Figure 4 for Figure 2 Another example of a plan view after removing the switch cover 110;

[0023] Figure 5 A circuit schematic diagram for establishing mechanical and electrical connections between the moving contact 108 and the stationary contact pieces 107, 107a;

[0024] Figure 6 It is a circuit schematic diagram after the moving contact 108 contacts the terminals 109 and 109a;

[0025] Figure 7 It is a circuit schematic diagram when the moving contact 108 is disconnected from the stationary contact pieces 107, 107a;

[0026] Figure 8 This is a structural diagram of the electromagnetic switch of the present invention after the starter is assembled;

[0027] Fig. 9 This is a circuit schematic diagram of the prior art electromagnetic switch when the main circuit is connected.

[0028] Explanation of the marks in the accompanying drawings: 1—gear spring, 2—driving gear, 3—front end cover, 4—check valve, 5—shift fork assembly, 6—electromagnetic switch, 6A—relay, 7—transmission reduction mechanism, 8—motor, 9—moving iron core, 10—coil assembly, 11—return spring, 12—moving contact assembly, 13—switch cover, 14—terminal, 15—flywheel gear ring, 100—electromagnetic switch, 101—moving iron core, 101a—end face of moving iron core 101, 102—return spring, 103—holding coil, 104—attracting coil, 105—housing, 105a—housing 10 5 riveted surface, 106—static iron core, 106a—end surface of static iron core 106, 107—first static contact piece, 107a—second static contact piece, 108—moving contact, 109—connection post, 109a—connection post, 110—switch cover, 111—insulating plate, 112—core shaft, 113—guide tube, 114—return spring, 115—screw, 116—conductive wire, 103a—power input end of holding coil 103, 103b—current outflow end of holding coil 103, 104a—power input end of attracting coil 104, 104b—current outflow end of attracting coil 104. DETAILED DESCRIPTION

[0029] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0030] See also Figure 2The electromagnetic switch 100 of the present invention comprises a moving iron core 101, a return spring 102, a holding coil 103, an attraction coil 104, a housing 105, a stationary iron core 106, a stationary contact piece 107, a stationary contact piece 107a, a moving contact 108, a terminal 109, a terminal 109a, a switch cover 110, an insulating plate 111, a core shaft 112, a guide tube 113, a return spring 114, etc.; wherein the stationary iron core 106, the holding coil 103, and the attraction coil 104 are fixed in the housing 105, and the switch cover 110 is fixed on the housing 105 and is located on one side of the stationary iron core 106 ( Figure 2 On the left side, Figure 2 The switch cover is fixed by the riveted surface 105a of the housing 105, the terminal 109 and the terminal 109a are fixed inside the switch cover 110, and the other end extends out of the switch cover, the moving iron core 101 is slidably arranged in the guide tube 113, and the guide tube 113 is fixed in the housing 105, one end of the return spring 102 is arranged on the static iron core 106, and the other end is arranged on the moving iron core 101, the moving contact 108 is arranged on the core shaft 112, and the core shaft 112 is slidably arranged on the static iron core 106, one end is opposite to the moving iron core 101, and the other end is arranged on the moving iron core 101. One end is connected to the switch cover 110 through a return spring 114; the core shaft 112 and the moving iron core 101 are designed separately; the static contact piece 107 and the static contact piece 107a are fixed to the static iron core 106 by screws 115, and the static contact piece 107 and the static contact piece 107a are insulated from the static iron core 106 by an insulating plate 111, and the static contact piece 107 and the static contact piece 107a are designed separately. Under the action of the return spring 114, the moving contact 108 establishes a mechanical contact relationship with the static contact piece 107 and the static contact piece 107a, and an electrical connection can be established when power is turned on.

[0031] See also Figure 3 The static contact piece 107 can be reliably welded to one end of a conductive wire 116, and the other end of the conductive wire 116 is led out from the switch cover 110. The static contact piece 107a is connected to one end of the attraction coil 104 (an electrical connection can be established when power is turned on), and the other end of the attraction coil 104 is led out from the switch cover 110. One end of the holding coil 103 is welded to the static iron core 106, and the other end of the holding coil 103 is led out from the switch cover. Figure 4 , the connection method of the electromagnetic switch coil is Figure 3 There is a difference, that is, the static contact piece 107 is connected to the attraction coil 104, the static contact piece 107a is connected to one end of a conductive wire 116, the connection mode of the coil 103 and the static iron core 106 remains unchanged, and the ends of the coil 103, the attraction coil 104 and the conductive wire 116 that are not involved in the connection are all led out from the switch cover. Figure 3 and Figure 4 The two connection modes have the same implementation results for the present invention.

[0032] See also Figure 2 and Figure 3 The static contact pieces 107 and 107a are fastened to the static iron core 106 by screws 115, wherein an insulating plate 111 is installed between the static contact pieces 107 and 107a and the static iron core 106, so that the static contact pieces 107 and 107a are reliably insulated from the static iron core 106; the moving contact 108 is in mechanical contact with the static contact pieces 107 and 107a under the action of the return spring 114, and an electrical connection can be established when power is turned on; when the electromagnetic switch 100 is powered on, the current flows in two ways, and the first current flows from the conductive wire 116 Enter the static contact 107, then enter the static contact 107a through the moving contact 108, and then enter the attraction coil 104 through the static contact 107a through the power input end 104a of the attraction coil 104, and then flow out from the outflow end 104b of the attraction coil 104 and enter the motor 8, and then flow out from the motor 8 and ground, forming a closed loop; the second current flows in from the power input end 103a of the holding coil 103, and after passing through the holding coil 103, the current flows out from the outflow end 103b of the holding coil 103, enters the static iron core 106 and grounds, and independently completes a closed loop. See the circuit schematic diagram Figure 5 After the current starts from the battery, it flows through the 30 terminal. Since the terminals 109 and 109a are in the disconnected state, a current closed loop cannot be formed; when the current flows through the 50 terminal, it is divided into two paths and enters the holding coil 103 and the attraction coil 104. One path of current enters the attraction coil 104 and flows through the static contact piece 107, the moving contact 108, and the static contact piece 107a, and then enters the motor 8, flows out from the motor 8 and is grounded to form a closed loop. The other path of current enters the holding coil 103, flows out from the holding coil 103 and is grounded to form a closed loop.

[0033] At the same time, after the electromagnetic switch 100 is energized, the holding coil 103 and the attracting coil 104 simultaneously generate electromagnetic attraction, and the moving iron core 101 moves toward the switch cover 110 (see Figure 2 ), when the moving iron core 101 hits the core shaft 112, it pushes the core shaft 112 to move toward the switch cover 110. Because the moving contact 108 is arranged on the core shaft 112, when the moving iron core 101 hits the core shaft 112 and pushes the core shaft 112 to move, the moving contact 108 is also pushed to move toward the switch cover 110 (see Figure 2), causing the moving contact 108 to disconnect the mechanical and electrical connection with the stationary contact piece 107 and the stationary contact piece 107a, the circuit of the attraction coil 104 is disconnected, and the electromagnetic attraction provided by the attraction coil 104 disappears. Because the current flowing through the holding coil 103 constitutes an independent closed loop, when the electromagnetic attraction of the attraction coil 104 disappears due to the first current being disconnected, the holding coil 103 will continue to generate electromagnetic attraction and offset the reaction force of the return spring 102, forcing the moving iron core 101 to continue to move toward the switch cover 110 until the end face 101a of the moving iron core 101 is completely in contact with the end face 106a of the stationary iron core 106. Therefore, it is relatively important to set the technical parameters of the holding coil 103. The technical parameters of the holding coil 103 that match different electromagnetic switches need to be changed accordingly according to the reaction force (i.e., spring reaction force and friction resistance) applied to the moving iron core of the electromagnetic switch, so that the electromagnetic suction force generated by the holding coil 103 can ensure that the moving iron core 101 moves until the end face 101a of the iron core 101 is completely in contact with the end face 106a of the static iron core 106. In the process of the moving iron core 101 pushing the core shaft 112 and the moving contact 108 toward the switch cover 110, the moving contact 108 contacts the two terminals 109 and 109a to connect the main circuit of the motor. After the moving contact 108 establishes an electrical connection between the two terminals (i.e., connects the starter main circuit), the moving iron core 101 will continue to push the core shaft 112 of the moving contact 108 to move a short distance until the moving iron core 101 is stopped by the end face 106a of the static iron core 106. For the circuit schematic diagram after the starter is connected to the main circuit, see Figure 6 After the current starts from the battery, it flows through terminal 30. Since the terminals 109 and 109a are in the on state, the current will flow from terminal 30 in two ways. One way is from terminal 30 through terminal 109, moving contact 108, and terminal 109a into motor 8, and flows out from motor 8 to ground to form a closed loop. The other way of current flows from terminal 30 through terminal 50. Since the static contacts 107 and 107a are in the off state, the current only enters the holding coil 103 from terminal 50, flows out from the holding coil 103 and is grounded to form a closed loop.

[0034] The electromagnetic attraction generated by the holding coil 103 is much smaller than the electromagnetic attraction generated by the attracting coil 104. Therefore, if the attracting coil 104 is disconnected, that is, the moving contact 108 is no longer in contact with the stationary contact piece 107 and the stationary contact piece 107a, the electromagnetic attraction of the electromagnetic switch will be greatly reduced. Therefore, if the electromagnetic switch of the present invention is installed on the starter, when the flywheel gear ring 15 of the top tooth of the starter driving gear 2 is not connected, after the attraction coil 104 of the electromagnetic switch is disconnected, the electromagnetic attraction provided by the holding coil 103 will not be enough to offset the reaction force of the return spring 102 after offsetting the reaction force of the gear spring 1, and the moving iron core 101 will no longer move toward the switch cover 110, thereby preventing the moving contact 108 from contacting the two terminals 109 and 109a, thus avoiding the connection of the main circuit of the motor, thereby avoiding the occurrence of the phenomenon of the starter running the milling gear engine at high power. For the circuit schematic diagram after the attraction coil 104 is disconnected, see Figure 7 Since the moving contact 108 and the stationary contact 107, the stationary contact 107a, the terminal 109, and the terminal 109a are all in the disconnected state, the current starts from the battery and only flows through the 30 terminal and the 50 terminal before entering the holding coil 103, flows out from the holding coil 103 and is grounded to form a closed loop, and the motor 8 is in the circuit disconnected state.

[0035] When the starter of the present invention top teeth the flywheel gear ring of the engine, since the starter obtains sufficient flexible meshing torque, the top teeth state lasts for tens of milliseconds, and the starter and the engine will mesh normally, that is, the drive gear 2 normally enters the flywheel gear ring 15, the starter is connected to the main circuit to work, and the engine is started normally; in extreme cases, even if the starter drive gear 2 top teeth the flywheel gear ring 15 cannot mesh, the electromagnetic switch 100 of the present invention will only maintain the starter in the top teeth state. After the starter is powered off, under the action of the tooth head spring 1 and the return spring 102, the drive gear 2 returns to the original static position through the fork assembly 5, and the starter waits for the next power-on start.

[0036] See also Figure 2 and Figure 8The operation process of the flexible meshing starter after adopting the electromagnetic switch 100 of the present invention is as follows: when the electromagnetic switch is energized, the holding coil 103 and the attraction coil 104 are energized at the same time, and an electromagnetic attraction force is generated, and the moving iron core 101 begins to move toward the switch cover 110. On the one hand, the moving iron core 101 pulls the fork assembly 5 through the joint 5a with the fork assembly 5, and the fork assembly 5 therefore shifts the one-way device 4 to move toward the flywheel gear ring 15. The driving gear 2 is installed on the one-way device 4, so the driving gear 2 is pushed by the one-way device 4 to move toward the flywheel gear ring 15. On the other hand, the current flowing through the attraction coil 104 passes through the static contact piece 107, the moving contact 108 and the static contact piece 107a, and then enters the motor 8. The motor 8 operates at low power, and the motor 8 slows down the drive gear 2 through the action of the transmission reduction mechanism 7 and the one-way device 4. The setting of the technical parameters of the attraction coil 104 is relatively important, and it is necessary to ensure that the motor 8 operates at low power. The torque provided by this low power can not only meet the torque required for the tooth tip of the offset drive gear 2 to hit the tooth tip of the flywheel gear ring 15 when the top tooth is pressed, but also not be greater than the torque required for the drive gear 2 to mill the flywheel gear ring 15. Therefore, the technical parameters of the attraction coil 104 need to be changed accordingly to match different starters.

[0037] See also Figure 2 and Figure 6 , when the driving gear 2 is rotating slowly and moving toward the flywheel gear ring 15 at the same time, if the driving gear 2 is normally meshed into the flywheel gear ring 15, the operation process of the starter starting the engine is as follows: the moving iron core 101 of the electromagnetic switch 100 continues to move toward the switch cover 110, and pulls the fork assembly 5 through the joint 5a with the fork assembly 5 to continue to move the driving gear 2 toward the flywheel gear ring. When the moving iron core 101 hits the mandrel 112, it pushes the mandrel 112 to move toward the switch cover 110. The movement of the mandrel 112 disconnects the connection between the moving contact 108 and the stationary contact piece 107 and the stationary contact piece 107a, and the attraction coil 104 is disconnected. The electromagnetic attraction generated by the attraction coil 104 disappears, and the moving iron core 101 offsets the return spring 1 under the electromagnetic attraction of the holding coil 103. 02's reaction force and other frictional resistances that prevent the moving iron core 101 from moving, the moving iron core 101 continues to move toward the switch cover 110, when the core shaft 112 pushed by the moving iron core 101 makes the moving contact 108 contact with the terminals 109, 109a and establish electrical connection, the starter main circuit is connected, the motor switches to a high-power working state, performs high-power operation, and starts the engine; at the same time, after the moving contact 108 contacts the two terminals 109, 109a and establishes an electrical connection between the two terminals, the moving iron core 101 will continue to push the core shaft 112 to move a short overtravel distance until the moving iron core 101 is stopped by the end face 106a of the static iron core 106; after the starter completes starting the engine, under the action of the return spring 102, the drive gear 2 returns to its initial static position.

[0038] When the driving gear 2 is rotating slowly and moving toward the flywheel gear ring 15, if the tooth tip of the driving gear 2 hits the tooth tip of the flywheel gear ring 15, the moving iron core 102, under the electromagnetic attraction generated by the holding coil 103 and the attracting coil 104, pulls the joint 5a of the fork assembly 5, thereby shifting the one-way device 4 to compress the tooth head spring 1. While the tooth head spring 1 is compressed, the moving iron core 101 moves toward the switch cover 110 to compress the tooth head spring 1 and compresses the return spring 102 by the same distance. Since the moving iron core 101 and the core shaft 112 are designed separately, the moving iron core 101 is There is a certain distance between 101 and the core shaft 112, the moving contact 108 continues to maintain mechanical contact and electrical connection with the static contact piece 107 and the static contact piece 107a, the attraction coil 104 remains energized, and the motor 8 continues to provide the rotational torque required for the flexible engagement of the drive gear 2, which is used to offset the top tooth state of the drive gear 2 on the tooth tip of the flywheel gear ring 15, so that the drive gear 2 is inserted into the flywheel gear ring 15, refer to

[0076] , the starter starts the engine according to the working process after the drive gear 2 engages with the flywheel gear ring 15, and after starting, under the action of the return spring 102, the drive gear 2 returns to the initial static position.

[0039] The following is an analysis of the technical bottlenecks of the traditional electromagnetic switch applied to the flexible engagement starter:

[0040] 1. For the electromagnetic switch of the prior art, at the moment when the starter is powered off, since the main circuit is in the on state, see Fig. 9 , the current flows from the battery through the 30 terminal, through the terminal 109, the static contact 108, and the terminal 109a, and then the current flows out in two ways. One way flows into the motor 8, and then flows out of the motor 8 and is grounded to form a closed loop. The other way of current enters the attraction coil 104. Since the attraction coil 104 and the head end of the holding coil 103 are connected together at the 50 terminal, the current flows out of the attraction coil 104 through the 50 terminal and enters the holding coil 103, and then flows out of the holding coil 103 and is grounded to form a closed loop. The currents flowing through the attraction coil 104 and the holding coil 103 are equal in magnitude and opposite in direction, and the electromagnetic attraction generated by the coils cancel each other out. If the number of turns of the attraction coil 104 and the holding coil 103 are basically the same, the electromagnetic attraction generated by the attraction coil 104 basically eliminates the electromagnetic attraction generated by the holding coil 103, see Figure 1, the moving iron core 101 loses the effect of electromagnetic magnetic force and moves toward the fork 5 under the reaction force of the return spring 102, and pushes the driving tooth head 2 back to the static position through the fork 5. At the same time, due to the retreat of the moving iron core 101, the moving contact 108 obtains moving space and also moves toward the fork 5 under the action of the spring reaction force, the terminals 109 and 109a are disconnected, the motor 8 is in the circuit-breaking state, and the starter is finished. If the number of turns of the attraction coil 104 and the holding coil 103 is greatly different, the electromagnetic attraction generated by the attraction coil 104 and the electromagnetic attraction generated by the holding coil 103 will not be completely offset, and the moving iron core 101 will be affected by the unoffset electromagnetic attraction. The return spring 102 must offset the remaining electromagnetic attraction before the moving iron core 101 can move toward the fork 5, which will cause the starter main circuit to be disconnected unreliably or unable to be disconnected.

[0041] Second, on the other hand, to achieve the purpose of flexible engagement of the starter, it is necessary to ensure that the current flowing into the motor 8 is sufficient to make the torsional torque provided by the motor 8 reach the torsional torque required for flexible engagement. For the electromagnetic switch of the prior art, there are only two ways to reduce the number of turns of the attraction coil or increase the cross-sectional area of ​​the diameter of the attraction coil. The first way is to greatly reduce the number of turns of the attraction coil 104. Although it ensures that the current flowing into the motor 8 is increased, the number of turns of the holding coil 103 also needs to be greatly reduced, otherwise the starter power off will be unreliable. See Fig. 9 , assuming that the electromagnetic attraction force generated by the attraction coil 104 and the holding coil 103 after the number of turns is reduced can make the moving contact 108 connect the terminal 109 and the terminal 109a. However, when the terminal 109 and the terminal 109a are connected, the attraction coil 104 will be short-circuited. Being short-circuited means that there is no current passing through the bypass due to the short circuit without resistance, and the electromagnetic attraction force of the attraction coil 104 disappears. See Figure 8, the electromagnetic attraction generated by the holding coil 103 is much smaller than the reaction force of the return spring 102 of the moving iron core 101. The moving iron core 101 will move toward the fork 5 under the action of the return spring 102, and the moving contact 108 will also move toward the fork 5 under the action of the return spring to disconnect the main circuit of the motor. The motor 8 is in a disconnected state and cannot work. In addition, it is not possible to increase the cross-sectional area of ​​the holding coil 103 to make the holding coil 103 generate a larger electromagnetic attraction to offset the reaction force of the return spring, because during the entire process of the starter operation, the holding coil 103 is always energized, which increases the cross-sectional area of ​​the holding coil 103, the current line density of the holding coil 103 is too large, and the temperature rise is too fast. The electromagnetic switch will burn out after a very short time of use. In addition, the effect of heat conduction causes the temperature of the attraction coil 104 to be too high. When starting again, the moving iron core 101 will not move or the flexible meshing torque is too small to produce a top tooth phenomenon. The second method is to increase the cross-sectional area of ​​the wire diameter of the attraction coil 104 while ensuring that the number of turns is basically the same. Although this can increase the current flowing into the motor 8 to a certain extent, the disadvantage is that the wire loss increases and the switch volume increases, which limits its application in the starter. In addition, as the number of turns of the attraction coil 104 increases, the electromagnetic attraction generated by the attraction coil 104 also increases, causing the impact force of the drive tooth head 2 on the end face of the flywheel ring gear 15 to increase, and the flywheel ring gear 15 will be damaged too quickly.

[0042] The following is an explanation of why the electromagnetic switch of the present invention uses double static contacts and the benefits of using double static contacts:

[0043] 1. The traditional electromagnetic switch is limited by the fact that the number of turns of the attraction coil and the holding coil must be consistent. To achieve the purpose of flexible engagement of the starter, the result is not ideal. Therefore, the present invention adopts the method of adding double static contacts to solve the limitation that the number of turns of the attraction coil and the holding coil of the traditional electromagnetic switch must be basically consistent. See the circuit schematic diagram Figure 6 During the period when the starter main circuit is connected, the attraction coil 104 is in an open circuit state. When the starter is powered off, the holding coil 103 is also powered off. Figure 8 , the moving iron core 101 loses the effect of the electromagnetic magnetic force and moves toward the direction of the fork 5 under the reaction force of the return spring 102. At the same time, after the moving contact 108 obtains the moving space, it also moves toward the direction of the fork 5 under the action of the spring reaction force. The terminals 109 and 109a are disconnected, the motor 8 is in an open circuit state, and the starter ends. Therefore, the present invention does not require that the number of turns of the attraction coil 104 and the holding coil 103 are basically the same, because when the starter is powered off, the current will not flow back from the attraction coil 104 to the holding coil 103, and there will be no unreliable starter power-off failure.

[0044] 2. See Figure 5If the flexible meshing torque of the starter drive gear head 2 is not enough, the current input to the motor 8 will be increased by increasing the wire diameter cross-sectional area of ​​the attraction coil 104 and reducing the number of turns of the attraction coil 104, thereby increasing the flexible meshing torque of the drive gear head 2; in addition, if the flexible meshing torque of the starter drive gear head 2 is too large, the wire diameter cross-sectional area of ​​the attraction coil 104 is reduced. It can be seen that the parameter adjustment means of the attraction coil 104 is free and is not affected by the holding coil 103. In addition, the present invention benefits from the restriction that there is no requirement for the attraction coil to keep the same number of turns as the holding coil. The number of turns of the attraction coil is generally much less than the number of turns of the holding coil. Therefore, the manufacturing cost of the electromagnetic switch is significantly reduced, and the reduction in the number of turns of the attraction coil can also reduce the volume of the electromagnetic switch, and the application range of the electromagnetic switch on other starters will also be wider.

Claims

1. An electromagnetic switch for a car starter, comprising a housing (105), a switch cover (110) fixedly connected to one end of the housing (105), a first terminal (109) and a second terminal (109a) fixedly arranged in the switch cover (110) and extending outwardly, a coil assembly arranged along the inner wall of the housing, a guide tube (113) arranged in the inner cavity formed by the housing (105) and the coil assembly, a static iron core (106) fixedly arranged on the inner side of the switch cover (110) and extending to the guide tube (113), and an inner end of the housing (105) is provided with a slideable guide tube (113) The movable iron core (101) is provided with an outer end extending outwards for connecting the shift fork assembly (5); a first return spring (102) is provided between the static iron core (106) and the movable iron core (101); a core shaft (112) passes through the central hole of the static iron core, and both ends extend out to slide; a movable contact (108) is fixedly sleeved on the core shaft (112), and the core shaft (112) is slidably provided on the static iron core (106), one end of which is opposite to the movable iron core (101), and the other end is connected to the switch cover (110) via a second return spring (114); characterized in that, A first static contact piece (107) and a second static contact piece (107a) are fixedly arranged independently of each other at the upper end of the static iron core (106), and the first static contact piece (107) and the second static contact piece (107a) are both insulated from the static iron core (106); the coil assembly comprises an attraction coil (104) and a holding coil (103) connected to each other, and when the power is initially turned on, the magnetic forces are superimposed, and the moving iron core (101) After moving a certain distance, the circuit of the attraction coil (104) is disconnected; one of the first static contact piece (107) or the second static contact piece (107a) is electrically connected to one end of the attraction coil (104); during operation, the other of the first static contact piece (107) or the second static contact piece (107a) is electrically connected to the starter motor part; the first static contact piece (107) is connected to one end of the attraction coil (104), and one end of the holding coil (103) is connected to the static iron core (106); the second static contact piece (107a) is connected to one end of the attraction coil (104).

2. The electromagnetic switch according to claim 1, characterized in that: The first stationary contact piece (107) and the second stationary contact piece (107a) are respectively fixed to the stationary iron core (106) by screws, and one end of the attraction coil (104) is welded to the stationary contact piece.

3. The electromagnetic switch according to claim 1, characterized in that: The first stationary contact piece (107) and the second stationary contact piece (107a) are insulated from the stationary iron core (106) by an insulating plate (111) sandwiched therebetween.

4. The electromagnetic switch according to claim 1, characterized in that: The second static contact piece (107a) is connected to one end of a conductive wire (116), and the other ends of the holding coil (103), the attracting coil (104) and the conductive wire (116) are all led out from the switch cover.

5. The electromagnetic switch according to claim 1, characterized in that: The first static contact piece (107) is welded to one end of a short conductive wire (116), the other end of the conductive wire (116) is led out from the switch cover (110), the other end of the attraction coil (104) is led out from the switch cover (110), and the other end of the holding coil (103) is led out from the switch cover.

6. An automobile starter, characterized in that: An electromagnetic switch as claimed in any one of claims 1 to 5 is provided.

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