Patent Grant
8776753
This application relates to the field of starter motor assemblies, and more particularly, to starter motor assemblies including two starter motors.
Starter motor assemblies are used to start vehicle engines, such as engines in heavy duty vehicles. The conventional starter motor assembly broadly includes an electric motor, a solenoid, and a drive mechanism.
The starter motor is placed in operation when a user closes an ignition switch on the vehicle and energizes the solenoid. Energization of the solenoid moves a solenoid shaft (also referred to herein as the “plunger”) in an axial direction. Movement of the solenoid plunger closes electrical contacts, thereby delivering full power to the electric motor. Movement of the solenoid plunger also moves a pinion of the drive mechanism into engagement with the engine flywheel gear. The electric motor delivers torque to the pinion. The pinion, in turn, causes the flywheel to rotate, thereby cranking the vehicle engine.
Once the vehicle engine starts, the operator of the vehicle opens the ignition switch, de-energizing the solenoid assembly. As a result of this deenergization, the magnetic field that caused the plunger to move decreases and is overcome by a return spring, causing the plunger to return to its original position. As the plunger moves to its original position, the pinion is pulled away from the ring gear, and the vehicle engine operates free of the starter motor.
Many starter motors include features that facilitate engagement of the pinion with the vehicle ring gear. One example of such a feature is known as a “soft-start” arrangement. Soft-start arrangements generally allow some limited power to be provided to the electric motor before the pinion engages the ring gear. As a result, the electric motor and pinion provide a “soft start” torque which helps the pinion clear any abutment with the ring gear, thus encouraging the pinion teeth to fully mesh with the ring gear teeth.
Soft-start arrangements typically utilize two coils, i.e., a pull-in coil and a hold-in coil. Both the pull-in coil and the hold-in coil are initially energized when the ignition switch is turned on, allowing current to flow through both coils. The electric field created by energization of the two coils encourages the plunger of the solenoid assembly to move in the axial direction, thus moving the pinion toward engagement with the ring gear of the engine flywheel. The pinion is driven by the electric motor of the soft-start arrangement such that the electric motor provides rotational torque to the pinion.
The electric motor of the soft-start arrangement is in series with the pull-in coil. Thus, the resistance of the pull-in coil limits current flowing through the electric motor during the process of pinion engagement with the ring gear. Because only limited current flows through the electric motor, the torque provided by the electric motor and the associated pinion are also limited (relative to the normal cranking torque) during the process of pinion engagement with the ring gear. As the pinion moves toward engagement with the ring gear, it freely rotates. However, once the pinion is abutted with the ring gear, the rotational speed of the pinion is limited as frictional drag between the pinion and ring gear prevents rapid acceleration of the pinion. Thus, the pinion rotates into full mesh with the ring gear at a relatively slow rotational speed (relative to the normal cranking speed). This relatively slow rotational speed of the pinion allows the pinion to more easily mesh with the ring gear.
When the plunger is moved to the point where the plunger contact disc engages the electrical contacts, the pull-in coil is effectively short circuited, and full power is delivered to the electric motor. The hold-in coil then holds the plunger in place in order to maintain engagement of the pinion with the ring gear during engine cranking.
Starter motors with soft-start arrangements are generally very effective in starting vehicle engines. However, some minor issues with soft-start arrangements occasionally exist with certain situations. One situation where an issue may exist is a heavy-duty application when two starter motors with soft-start arrangements are used to crank a single engine. In this situation, the two starter motors are connected electrically in parallel across a 24V battery pack on the vehicle. This arrangement of two starter motors works quite well for actual starting of the engine. However, the two starter motors operate independent of each other, and do not always provide full cranking power at the same point in time. This time difference may be 0.25 seconds or larger. Because of this, a noise may be encountered as the first starter motor is fully engaged with the ring gear and cranking the engine while the second starter motor is still trying to engage the ring gear. Accordingly, it would be desirable to provide a dual starter motor arrangement that provides for reduced noise over existing dual starter motor arrangements. It would also be desirable if such a dual starter motor arrangement could be implemented with only limited additional costs than existing dual starter motor arrangements.
In accordance with one embodiment of the disclosure, a starter motor arrangement comprises a battery, a first starter motor and a second starter motor. The first starter motor includes a solenoid, an electric motor, a battery terminal, and a ground terminal. The battery terminal of the first starter motor is connected to a first terminal of the battery. The second starter motor includes a solenoid, an electric motor, a power terminal and a ground terminal. The battery terminal of the second starter motor connected to the ground terminal of the first starter motor. The ground terminal of the second starter motor is connected to a second terminal of the battery.
Pursuant to another embodiment of the disclosure, a starter motor arrangement comprises a battery, a first starter motor, and a second starter motor, all connected in series. The first starter motor is connected to the battery and includes a first pinion gear. The second starter motor is connected to the first starter motor and includes a second pinion gear. The first pinion gear and the second pinion gear are configured to engage an engine ring gear when electrical current flows through the first starter motor and the second starter motor.
In accordance with yet another embodiment of the disclosure, a method of starting a vehicle engine comprises energizing a first solenoid of a first starter motor, wherein the first starter motor includes a first pinion. The method further comprises energizing a second solenoid of a second starter motor, wherein the second starter motor includes a second pinion. In addition, the method comprises moving the first pinion toward a ring gear of the vehicle engine, and moving the second pinion toward the ring gear of the vehicle engine. Furthermore, the method comprises cranking the vehicle engine with the first starter motor or the second starter motor only if both the first pinion and the second pinion move into meshed engagement the ring gear of the vehicle engine.
The above described features and advantages, as well as others, will become more readily apparent to those of ordinary skill in the art by reference to the following detailed description and accompanying drawings. While it would be desirable to provide a dual starter motor arrangement that provides one or more of these or other advantageous features, the teachings disclosed herein extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the above-mentioned advantages.
With reference to
As shown in
With reference again to
As indicated by arrow 12 in
As illustrated in
With particular reference to
The battery 42 includes a positive terminal 44 and a negative terminal 46. A “B+” cable 48 is coupled to the positive terminal 44. A ground cable 92 is coupled to the negative terminal 46 (which may also be referred to herein as a “ground terminal”). In the disclosed embodiment, the battery is a 24V battery, but it will be recognized that batteries of different voltages and ratings may be used in different applications.
The electrical components of the first starter motor 20 include an electric motor 22 and a solenoid assembly 70. The solenoid assembly 70 includes a pull-in coil 71 and a hold-in coil 72, stationary contacts 73a and 73b, and a plunger contact 74 provided on a plunger 75. The pull-in coil 71, hold-in coil 72 and contacts 73 and 74 are commonly found on solenoid assemblies for starter motors, and may be provided in various embodiments as will be recognized by those of ordinary skill in the art.
The first starter motor 20 also includes a battery terminal 76, a ground terminal 77, and a solenoid terminal 78. The battery terminal 76 is connected to the B+ cable 48, thus coupling the first starter motor 20 to the battery 42. Within the starter motor 20, the battery terminal 76 leads to the first stationary contact 73a. The solenoid terminal 78 leads to a node of both the pull-in coil 71 and the hold-in coil 72. The ground terminal 77 leads to an opposite node of the hold-in coil and the electric motor 22. A jumper cable 90 is also connected to the ground terminal 77. However, the jumper cable 90 does not connect the ground terminal 77 of the first starter motor to the negative terminal of the battery 42, but instead connects the ground terminal 77 to the second starter motor 30, as described below.
The jumper cable 90 connects the first starter motor 20 to the second starter motor 30. In particular, the jumper cable 90 extends between the ground terminal 77 of the first starter motor 20 and a battery terminal 86 of the second starter motor 30. Thus, the jumper cable connects the first starter motor 20 to the second starter motor 30 in a series connection. The jumper cable 90 may be provided by a copper wire or any of various other conductors offering relatively low losses.
The second starter motor 30 generally includes the same internal components and terminals as the first starter motor, and the components are generally arranged in the same manner. Accordingly, as illustrated in
The first magnetic switch 50 is coupled to the first starter motor 20 and is configured to control the current flowing to the pull-in coil 71 and hold-in coil 72 on the solenoid assembly 70. The first magnetic switch 50 includes a solenoid assembly 51 including a coil 52, a plunger 53, plunger contact 54, and stationary contacts 55. The first magnetic switch also includes four terminals including a battery terminal 56, a solenoid terminal 57, an ignition switch terminal 58 and a ground terminal 59. The battery terminal 56 of the magnetic switch 50 is connected to the battery terminal 76 of the first starter motor 20. The solenoid terminal 57 of the magnetic switch 50 is connected to the solenoid terminal 78 of the first starter motor 20. The ignition switch terminal 58 is connected to an ignition switch 18 in the vehicle. The ignition switch 18 (which may also be referred to as a “customer switch” or a “key switch”) is controlled by the operator of the vehicle, as will be recognized by those of ordinary skill in the art, by moving the ignition switch between an on an off position. In the embodiment of
The second magnetic switch 60 is coupled to the second starter motor 30 and is configured to control the current flowing to the pull-in coil 81 and hold-in coil 82 on the solenoid assembly 80. The second magnetic switch 60 generally includes the same internal components and terminals as the first magnetic switch 50, and the components are generally arranged in the same manner. Accordingly, as illustrated in
Operation of the dual starter motor arrangement is now described with reference to
When the battery voltage applied to the ignition switch terminals 58 and 68, the second magnetic switch 60 closes first because the coil 62 in the second magnetic switch 60 is connected directly to ground via ground terminal 69. By contrast, the ground terminal 59 of the first magnetic switch 50 is connected to the battery terminal 56 of the second magnetic switch 60. Thus, the coil 52 in the first magnetic switch 50 does not have current flow until the second magnetic switch 60 closes and provides a path to ground.
Current flowing through the coil 62 in the second magnetic switch 60 creates a magnetic field that moves the plunger 63 toward the stationary contacts 65. When the plunger contact 64 engages the stationary contacts 65, the second magnetic switch 60 is closed, and a path to ground is provided for the coil 52 of the first magnetic switch 50. This allows current to flow through the coil 52, creating a magnetic field that moves the plunger 53. Plunger 53 moves until the plunger contacts 54 engage the stationary contacts 55, thus closing the first magnetic switch 50.
With both the first and second magnetic switches 50 closed, current flows through both the pull-in coils 71, 81 and the hold-in coils 72, 82 of both the first and second solenoid assemblies 70, 80. The current flowing through the coils 71, 72, 81, 82 creates a magnetic field that encourages the plungers 75, 85 to move toward the stationary contacts 73, 83. Current flowing through the pull-in coils 71, 81 is also directed through the electric motors 22, 32 as soft start current. This soft start current is generally controlled by the resistance of the pull-in coils 71, 81 of the solenoid assemblies 70 and 80, limiting the torque the electric motors 22, 32 provide to the pinion. At this point, the electric motors 22, 32 behave independently of each other, as the general operation of one motor 22 is not dependent on the other motor 32 at this time, and vice-versa.
As the plungers 75, 85 move the pinions 26, 36 and the plunger contacts 74, 84, one of three possible results will occur. First, the pinions 26, 36 of both starter motors 20, 30 may mesh into the ring gear 9 nearly synchronous, with the plunger contacts 74, 84 engaging the stationary contacts 73, 83 nearly synchronous. Second, there may be a significant time delay between meshing of the pinion 26 of the first starter motor 20 with the ring gear 9 and meshing of the pinion 36 of the second starter motor 30 with the ring gear 9, or vice-versa (i.e., either pinion 26 or 36 could be first to engage the ring gear). Third, one or both starter motors 20, 30 could experience a click-no-crank (“CNC”) event (i.e., one or both pinions 26, 36 fail to mesh with the ring gear).
In the first case where both the pinions 26, 36 mesh into the ring gear 9 in nearly synchronous fashion, the plunger contacts 74, 84 also engage the stationary contacts 73, 83 in nearly synchronous fashion. When the plunger contacts 74, 84 engage the stationary contacts 73, 83, the pull-in coils 72, 82 are short-circuited, and full power is delivered to the electric motors 22, 32. With high current flowing through the electric motors 22, 32, the electric motors 22, 32 provide an increased torque to the pinions 26, 36 that is sufficient to turn the ring gear 9 and crank the vehicle engine 8. Once engine start occurs, the operator turns the ignition switch to the off position. This reduces and eventually eliminates current flow in all solenoid coils 71, 72, 81, 82, causing the solenoid plungers 75, 85 to retract and open the motor contacts 73, 83. This stops the flow of current through the electric motors 22, 32 and ends the cranking process.
In the second case where there is a significant time delay between meshing of the first pinion 26 with the ring gear 9 and meshing of the second pinion 36 with the ring gear 9 (or vice-versa), the series connection between the starter motors 20 and 30 prevents high current from flowing through the electric motor 22 of the first starter motor 20 without also flowing flow through the electric motor 32 of the second starter motor 30. For example, consider a moment in time where the first pinion 26 has engaged the ring gear 9, while the second pinion 36 continues moving toward the ring gear 9 but has yet to engage the ring gear 9. In this situation, the plunger contact 84 has yet to engage the stationary contacts 83 to allow full current flow through the second starter motor. Because the starter motors are in series, the current flowing through the first starter motor 20 is limited to the current flowing through the second starter motor 30 (i.e., as shown in
Because of this second case where one motor meshes before the other and the related circuitry, the windings of the typical 12V hold-in coil may be modified from use in the dual starter motor arrangement disclosed herein. The reason for this is that the applied voltage for the starter motor engaged first is higher than what it would normally experience since the resistance of the other starter motor in this condition does not effectively cut the battery pack voltage in half. However, this is significantly less than 24V.
In the third case where one or both starter motors 20, 30 experience a CNC event, the overall crank of the starter motor arrangement 10 will behave as if there was only one starter motor experiencing the CNC event. In particular, high current will not flow to either electric motor 22 or 32, and there will only be a “click” sound when the pinion strikes the ring gear. The reason for this is the same as discussed in previously, that the series connection arrangement results in the amount of current flowing through one starter motor being limited to the amount of current flowing through the second starter motor. If high current cannot flow through the electric motor 22 of the first starter motor 20, high current cannot flow through the electric motor 32 of the second starter motor 30. Accordingly, no cranking sound is made since high current does not flow in either motor. In this case, the customer will typically move the ignition switch back to the off position, and then make another attempt to crank the vehicle engine by returning the ignition switch to the on potion, thus repeating the entire process.
As described above, operation of the starter motor arrangement involves moving the first pinion toward a ring gear of the vehicle engine while also moving the second pinion toward the ring gear of the vehicle engine. However, as will be apparent from the above disclosure, the cranking the vehicle engine with either the first starter motor or the second starter motor occurs only if both the first pinion and the second pinion move into meshed engagement with the ring gear of the vehicle engine. In other words, when the pinion from one first starter motor moves into meshed engagement with the ring gear, that starter motor does not crank the vehicle engine until the pinion from the other starter motor also moves into meshed engagement with the ring gear. In addition, if the pinion from one starter motor experiences a CNC event, the other starter motor will not crank the vehicle engine.
The foregoing detailed description of one or more embodiments of the dual starter motor arrangement has been presented herein by way of example only and not limitation. It will be recognized that there are advantages to certain individual features and functions described herein that may be obtained without incorporating other features and functions described herein. Moreover, it will be recognized that various alternatives, modifications, variations, or improvements of the above-disclosed embodiments and other features and functions, or alternatives thereof, may be desirably combined into many other different embodiments, systems or applications. Presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the appended claims. Therefore, the spirit and scope of any appended claims should not be limited to the description of the embodiments contained herein.
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