Patent Application
20180171958
This application relates to the field of starter motor assemblies, and more particularly, to starter motor assemblies including two or more starter motors.
Starter motor assemblies are used to start vehicle engines, such as engines in heavy duty vehicles. The conventional starter motor assembly 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.
It is well-known by those having ordinary skill in the art that conventional starter systems have been susceptible to a problematic failure mode known in the art as “click-no-crank.” Click-no-crank refers to the axial face of the starter assembly pinion being driven into abutment with the interfacing axial surface of the engine ring gear, rather than the teeth of the ring gear and pinion becoming enmeshed. Such incidences involve energization of the starter solenoid assembly during operator activation of the switch, which results in the pinion-ring gear abutment (typically resulting in an audible “click”) blocking movement of solenoid switch contact plate, thereby preventing the switch from closing. Prolonged application of electrical power to solenoid assembly during an abutting condition between the pinion and ring gear can prevent the gears from meshing.
To address click-no-crank problems, some starter motors include a feature known as “soft-start.” 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. However, this “soft-start” feature just mentioned is sometimes insufficient to overcome a click-no-crank event.
One of the historical challenges of dual and triple starter applications of the type subject of this disclosure has been the reliable engagement of all starters, virtually simultaneously. Dual and triple starter systems are typically provided in large heavy-duty equipment. For example, large unmanned generators with engines as large as 150 liters commonly have three starter assemblies to crank the engine. The starting operation of such generators can be entirely automated, being automatically triggered at the start of a power failure. In these circumstances, a click-no-crank event can result in automated cranking of the starters for 30 or 60 seconds, or whatever time interval is programmed, during which time a very high current passes through the coils, which can ultimately burn up the coils and cause the starter assemblies to fail. Similar problems may occur in other large industrial equipment, such as bulldozers, large trucks and other heavy duty equipment.
It would be desirable to achieve a cost-effective means for ensuring reliable and simultaneous engagement of all starters in a system using two or more starters that crank a single engine.
The present disclosure teaches a system for starting an engine in which at least two starter assemblies are employed to crank a ring gear of an engine. At least one of the starter assemblies has a “smart relay” configured with an auto-retry function that detects abutment and corrects it by powering the solenoid off and then on again. Advantageously, multiple starter assemblies can be in electrical communication with one another so that a click-no-crank event in one or more of the starter assemblies can be corrected.
In one form thereof, the present disclosure teaches a system for starting an engine. The system includes a first starter assembly and a second starter assembly operable with the first starter assembly to crank an engine. Optionally, additional starter assemblies may be included. A smart relay is operably connected to the first starter assembly and has an auto-retry function. During a starting operation, if a sensed voltage monitored by the smart relay falls below a threshold level within a predetermined time after application of electrical power to a solenoid of the first starter assembly, the smart relay activates the auto-retry function to switch electrical power to the solenoid off and on, whereby a click-no-crank event can be corrected.
In some embodiments, the M sense terminal of the smart relay is electrically connected to the second starter. As such, engagement of the second starter assembly with the engine disables the auto-retry function of the smart relay. In other embodiments, engagement of the first or second starter assembly with the engine disables the auto-retry function of the smart relay.
The second starter assembly may optionally comprise a second smart relay which has the same auto-retry functionality as the first smart relay. In such a system with two smart relays, the first smart relay and the second smart relay typically have interconnected M-terminal voltage sense leads. In this system, engagement of either one of the first and second starter assemblies with the engine disables the auto-retry function of both the first and second smart relays.
In a further embodiment, the system includes a third starter assembly operable with the first and second starter assemblies to crank the engine. The third starter assembly has a third smart relay that has the auto-retry function. In this system with three starter assemblies, engagement of any one of the first, second or third starter assemblies with the engine disables the auto-retry function of the first, second and third smart relays. The first, second and third smart relays typically have their M-terminal voltage sense leads interconnected to facilitate this feature.
In another embodiment having two starter assemblies, only one of the two starter assemblies has a smart relay, the other having a conventional relay switch. In such a system, engagement of the first or second starter assembly with the engine disables the auto-retry function of the smart relay. Failure of both the first and second starter assemblies to engage with the engine activates the auto-retry function of the smart relay. It is possible in accordance with this disclosure to have systems with more than two starters, e.g., a triple starter system, with only one of the starters having a smart relay that corrects an abutment condition of all three starters.
It has been found, surprisingly, that using a single smart relay in a system with multiple starters can overcome all click-no-crank events in the starter assemblies of such system. That is, in systems in accordance with these teachings, when all starter assemblies in the system abut at the beginning of a starting operation, the starter assembly having the smart relay activates its auto-retry function, which brings this starter into engagement with the ring gear. Then the other lagging starter assemblies will engage the rotating ring gear. Providing only one of the starter assemblies with a smart relay in a multiple starter system yields benefits in terms of cost savings and implementation.
The above-mentioned aspects of exemplary embodiments will become more apparent and will be better understood by reference to the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:
The embodiments described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of this disclosure.
With further reference to
As indicated by arrow 12 in
A smart relay 62 suitable for practice with this disclosure is described in detail in WO 2016/090185 and reference for further details of the smart relay is made thereto. Essentially, smart relay 62 can be configured with several corrective functions, one of which is an “auto-retry” function to correct a “click-no-crank” problem, as described above. As described in detail in WO 2016/090185, smart relay 62 includes a controller that, during a starting operation, monitors motor energization voltage. If the voltage monitored falls below a predetermined threshold level within a predetermined time after the application of electrical power to the solenoid assembly 38, the controller of smart relay 62 opens and re-closes the switch to switch electrical power to the solenoid assembly 38 off and on. This functionality can correct a click-no-crank event during the starting operation.
For purposes of this disclosure, the term “smart relay” should be construed broadly, but in all events should be construed to include the “auto-retry” functionality described in the preceding paragraph and in more detail in WO 2016/090185. Of course, the smart relay may be configured with additional functionalities that are described in detail in WO 2016/090185.
Turning now to
With the system shown in
In view of the exemplary embodiments discussed above, one of skill in the art could implement variations on starter systems with multiple starters. For example, a system having three starter assemblies with only one starter assembly having a smart relay could be configured. One of skill in the art will appreciate the advantages of such a system, such as cost savings from using only one versus multiple smart relays, the advantageous ease of implementation, and the simplicity of the configuration, i.e., fewer complicated parts. In this system, if all three starter assemblies abut (click-no-crank), then the auto retry function of the starter assembly with the smart relay will activate to clear the abutment. Then, when the ring gear begins to rotate, the other two lagging starter assemblies will be able to clear their abutments and engage the ring gear. On the other hand, if either of the two starter assemblies not having the smart relay engage first, then the auto-retry feature of the starter having the smart relay will become disabled, in which event the lagging starters will engage as the ring gear begins to rotate.
While exemplary embodiments have been disclosed hereinabove, the present invention is not limited to the disclosed embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of this disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
