THEREOF

RELATED APPLICATION

[0001] Benefit is claimed under Indian Provisional Application No: 2389 /DEL/2010, titled "Bearing unit, wheel hub, two wheeler, vehicle and method, by Aktiebolaget SKF, filed on 05/10/2010, which is herein incorporated in its entirety by reference for all purposes.

TECHNICAL FIELD OF THE INVENTION

[0002] Embodiments of the invention generally relate to the field of start-stop systems in automobiles, and more particularly to use of a bearing unit in switching off and on ignition in automobiles.

BACKGROUND OF THE INVENTION

[0003] In today's world, pollution caused by automobiles is at an all time high and this is especially evident at long stops like traffic signals, traffic jams, where vehicles pile up. When engines of the automobiles are in an idle state, large amount of fuel is wasted and polluting emissions (toxic gases) are also released. This leads to more usage of fuel and with increasing fuel costs, it poses even more problems. Further, there occurs unnecessary engine usage in idling, which causes more part wear of engine components. Start-stop systems are thus especially designed to overcome this problem. In the start-stop systems, needless engine idling is eliminated. The user may also sometimes want to disable the stop and start function, and be able later on to activate it again. The easiest manner is to have a dedicated on/off button to enable or disable the stop and start function. This solution requires a specific button, which increases the product cost.

SUMMARY OF THE INVENTION

[0004] A bearing unit for switching off and on ignition in automobiles and a method thereof is disclosed. According to one aspect of the invention, a bearing unit is used for switching off and on ignition in automobiles. The bearing unit includes a first element and a second element which are rotatable against each other. The first element and the second element are raceway elements and rolling bodies are arranged between the first element and the second element to form a rolling bearing.

[0005] The bearing unit also includes a device for detecting and analyzing at least rotation and non-rotation occurring between the first element and the second element. Depending on the result of the analyzing, an ignition of an automobile with a combustion engine is switched off.

[0006] The device is designed for measuring speed of the automobile and includes an electronic switch to switch off the ignition. The device includes a magnetic target ring which is coupled to the rotating element and a sensor which is adapted to the magnetic target ring and coupled to the non rotating element. The sensor and the switch forms one structural mechatronic unit. The device is connectable wirelessly or via a cable to other components of the automobile. The automobile may be a two wheeler, a three wheeler or a four wheeler and the like, and the bearing unit forms a part of a wheel hub of the automobile. The device also switches on the ignition of the automobile after switching off the ignition.

[0007] According to another aspect of the invention, method of using a bearing unit in switching off and on ignition in automobiles is described. Other features of the embodiments will be apparent from the accompanying drawings and from the detailed description that follows. BRIEF DESCRIPTION OF DRAWINGS

[0008] FIG. 1 shows a cross-sectional view of a bearing unit for switching off and on ignition in an automobile, according to one embodiment;

[0009] FIG. 2 shows an example wheel of a two wheeler where the bearing unit of FIG. 1 is deployed, according to one embodiment;

[0010] FIG. 3 shows a process flow diagram of optimized stop of the automobile using the bearing unit of FIG. 1 , according to one embodiment;

[0011] FIG. 4 shows a process flow diagram of restart of the automobile using the bearing unit of FIG. 1 , according to one embodiment; and

[0012] FIG. 5 shows a process flow diagram of switching on and off the bearing unit described in FIG. 1 , according to one embodiment.

[0013] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present invention in any way.

DETAILED DESCRIPTION

[0014] A bearing unit for switching off and on ignition in automobiles and a method thereof is disclosed. The following description is merely exemplary in nature and is not intended to limit the present invention, applications, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0015] FIG. 1 shows a cross-sectional view of a bearing unit for switching off and on ignition in an automobile, according to one embodiment. The automobile may be a two wheeler, a three wheeler or a four wheeler. The bearing unit includes a first element (the bearing inner ring 104) and a second element (the bearing outer ring 102) which are rotatable against each other. For example, the first element and the second element are raceway elements, where rolling bodies are arranged between the first element and the second element to form a rolling bearing. The bearing unit also includes a device for detecting and analyzing at least rotation and non-rotation occurring between the first element and the second element. Depending on the result of the analyzing, the ignition of the automobile (with a combustion engine) is switched off and on. The device includes an electronic switch 106 to switch off the ignition.

[0016] In one example, the device is designed for measuring speed of the automobile (using a sensor 116). The device also includes a magnetic target ring 114 which is coupled to the intentionally rotating element and the sensor 116 which is adapted to the magnetic target ring 114 and coupled to the intentionally non rotating element. In one embodiment of the present invention, the sensor 116 and the electronic switch 106 form one structural mechatronic unit. The device is connectable wireless and/or via a cable to other components of the automobile. It should be noted that the bearing unit forms a part of a wheel hub of the automobile.

[0017] To provide a more intuitive stop in comparison with the existing ignition key or engine kill switch, the bearing unit monitors movement of wheel of the automobile intrinsically. Based on conditions of no movement of automobile, signal indicating state of engine and/or engine rpm, the bearing unit sets up a time delay after which the engine management unit or the pulsar coil is grounded for a certain short time period. This results in the shutting off of the engine. This time delay may also be optimized based on gear position.

[0018] The automobile may have an engine management unit or a pulsar coil which allows switching off the ignition efficiently. To provide output to them (cutting off), this connection from the intuitive stop unit could be via existing wires which need to be tapped. This is done with the aid of standard automotive connectors.

[0019] To detect the stationary condition of the autombile, the bearing unit measures the pulses (or lack of it) emanating from the roller bearing. These pulses are generated by the sensor 116 which gets excited by the movement of the magnetic target ring 114. This magnetic target ring 114 is mounted on the roller bearing which is installed into the wheel hub of the automobile (as shown in FIG. 2). Thus, when the wheel rotates, the roller bearing and the magnetic target ring 114 rotates, enabling the sensor 1 16 to generate pulses which are sensed by the bearing unit. The lack of pulses, thus naturally denotes that the wheel is not moving and is a pre-condition for shutting of the engine. The second condition is to monitor the engine rpm, as it is useful to shut off the engine only if it is already on. The third condition is the time delay (before shutting off the engine). This can be a standard setting of 'x' seconds.

[0020] Alternatively, this can also be calculated based on the gear position. Thus, when the gear is in neutral the time delay is shorter and while the gear is engaged, the time delay is longer. This has been made keeping in mind user behavior. The bearing unit allows shutting of in neutral gear (with lesser time delay) which suggests gradual stopping or low traffic. It also allows shutting off in gear as this is a common habit among two-wheeler riders. But this is achieved without the inconvenience of frequent stopping in heavy stop-go traffic. A longer time delay of stopping and a minimum time of stop between two stops are recorded, enabling this function. To stop the engine, the bearing unit needs to know if the engine is on and only then attempt to shut it. To have this information, different possibilities exist which are to measure the pulsar coil intensity (this sensor gives the top turn information for the engine management unit) and to measure the engine rpm information from the engine management unit. It is an electrical signal to the dashboard to indicate the engine speed. [0021] An important point is to not modify and perturb the current safety system for an electric restart system. Thus after the unit has shut off the engine, it enables the automobile user to restart at any time by pressing the starter button or activating a throttle via the bearing unit. When the throttle is activated, the bearing unit sends signal to starter relay to switch on the automobile.

[0022] FIG. 2 shows an example wheel of a two wheeler 202 where the bearing unit of FIG. 1 is deployed, according to one embodiment. The bearing unit may be deployed in other automobiles such as three wheelers and four wheelers. As shown, a sensor block 212 is attached to a bearing 206 and forms the bearing unit which is mounted on a wheel hub 204 of the two wheeler 202. The bearing unit enables 6-10% fuel savings in the two wheeler 202 depending on city traffic conditions. Emissiosns released in the form of toxic gases during engine idling are eliminated in automobiles through use of the bearing unit. The noise and vibration, both externally as vehicle noise and internally within the engine of the automobile are reduced, thus reducing part wear and increasing the overall life of engine.

[0023] FIG. 3 shows a process flow diagram 300 of optimized stop of the automobile using the bearing unit of FIG. 1 , according to one embodiment. At step 302, the bearing unit is on. At step 304, it is determined whether the wheel speed is equal to zero. If it is determined not, the process 300 is routed back until the wheel speed is sensed zero. If it is determined so, at step 306, it is determined whether the engine of the automobile is on. If it is determined not, the process 300 is routed back to perform step 304. If it is determined so, at step 308, a timer is started to find out the time delay since the wheel speed of the automobile is sensed zero.

[0024] When the automobile is in neutral, the bearing unit selects a smaller time delay, e.g., 6 seconds. This usually corresponds to user behavior indicating gradual stop or low traffic. When the automobile stops while in gear, the bearing unit selects a larger time delay e.g., 12 seconds. This usually corresponds to user behavior indicating a short stop or heavy traffic where the user is anticipating frequent movement and does not want the engine shutting of frequently. At step 310, it is determined whether sufficient time has elapsed since the last stop of the engine of the automobile. If it is determined not, the process 300 is routed back to perform step 304. In one example embodiment, the bearing unit checks the time between two stops and if this falls to less than a predetermined value, say 30 seconds, the bearing unit disables itself from shutting of the motorcycle till some length of time elapses. At step 312, after the predetermined value of time delay, the engine is stopped. If another embodiment, the throttle may be provisioned to reset the engine from stopping. Also, user of the automobile may receive warning (visual warning or by vibration of handle of the automobile) that the engine is stopping.

[0025] The bearing unit achieves stopping of the engine by several ways. In one example, it is achieved by grounding the signal from the engine management unit to the engine. This may also be done by grounding the signal from the pulsar coil. A third way exists by cutting the power supply to the engine management unit. For all these possibilities, the grounding is applied for at least a minimum time period (e.g., 1-2 seconds), to allow the rotary inertia of the magneto to fall sufficiently to a low value such that it does not restart the engine. If the bearing unit provides function other than starting, it can allow the start with a new condition. For example, for a stop and start system, the restart is allowed by the bearing unit only if the bearing unit has stopped the automobile previously. Another example is that the restart may be allowed only if the motorbike has stalled.

[0026] To use this intuitive stop function only if the engine is sufficiently warmed up (especially in cold start conditions when the battery voltage might be a little less than ideal), the bearing unit may allow this function only if the engine is hot. For that, the automobile may have a thermal sensor and the bearing unit waits till a fixed temperature before stopping the engine. Or instead of the thermal sensor, the bearing unit may wait a fixed time after the first engine running or/and a determined distance of the automobile or/and a minimum speed of the vehicle (this new information can come from the vehicle displacement sensor, the wheel speed sensor, for example), before the engine is allowed to be shut off by the bearing unit.

[0027] Also, to preserve the battery, sensor block does 112 of the bearing unit monitors a battery voltage state of the automobile. If it is detected that the voltage is falling below a certain predetermined value deemed as the low voltage point of the battery, the sensor block does 112 disables the shutting off of the engine, allowing time for the battery to recharge. For example if the battery voltage is under 9V whereas the normal voltage value is 12V, the bearing unit disables the engine stop to preserve the battery.

[0028] FIG. 4 shows a process flow diagram 400 of restart of the automobile using the bearing unit of FIG. 1 , according to one embodiment. Throttle signal from the throttle sensor is used in restarting the automobile. At step 402, the bearing unit is on. At step 404, it is determined whether the engine is off, the clutch is one and neutral on. If it is determined not, the process 400 repeats until the engine is off. If it is determined so, at step 406, it is determined whether the throttle is on. If it is determined not, the process is routed back to step 404, else at step, a timer is started.

[0029] At step 410, it is determined whether the predetermined time has reached when the clutch is on, neutral on and the engine off. If it is determined so, at step 412, the throttle sensor or a switch is closed. At step 414, it is determined whether the engine speed is above 1000 rotations per minute (rpm). If not, the process 400 waits until the engine speed is above lOOOrpm and at step 416, the switch is opened when the engine speed goes above l OOOrpm. The starter motor starts not only when the starter button is activated but also if the user accelerate.

[0030] The automobile must have the throttle sensor (or switch) given an indication of the activation or not of the throttle by the user. This sensor could be an instrumented carburettor or a slide switch. To detect the throttle opening, signal from the throttle sensor is measures. If the signal is linear in function of the throttle opening, the bearing unit allows the restart after fixed voltage amplitude. If the sensor is a switch, the bearing unit allows the restart after a switch commutation. The bearing unit determines whether the engine is running or not in different ways. The pulsar coil intensity is measured which gives the top turn information for the engine management unit. The engine rpm is measured from the engine management unit. It is an electrical signal to the dashboard to indicate the engine speed. The current safety system for an electric restart system is not modified and perturbed. This safety purpose is composed with different switch to allow the restart only in safe condition when clutch pressed if the gearbox is not in neutral and in neutral position. [0031] To optimize the time during witch the starter motor cranks, the bearing unit measures the variation of the engine speed when only the electrical motor turns and when the engine is in idle speed. For that, the engine speed information is obtained from the pulsar coil or form the engine management unit, one pulse per turn. The main goal is to cut the electric motor supply when the engine is idling.

[0032] To preserve the battery, the bearing unit allows a limited number of restart trying. For example, the bearing unit allows 3 restarts trying with the intuitive restart function, each trying lasts 2 seconds. Also, if the bearing unit provides other function than the restarting, it can allow the start with a new condition. For example for a stop and start system, the restart is allowed by the system only if the system has stopped the vehicle previously. In another example, the restart is allowed if the motorbike has stalled.

[0033] To use this intuitive restart function only if the restart is easy for the electrical motor, the bearing unit may allow this function only if the engine is hot. For that, the automobile should have a thermal sensor and the bearing unit waits a fixed temperature. Without this sensor, the bearing unit may wait a fixed time after the first engine running, a determined distance of the vehicle or/and a minimum speed of the vehicle (for example, this new information is obtained from the vehicle displacement sensor, the wheel speed sensor). To prevent battery problem, the bearing unit allows the restart of the automobile only if the battery voltage is greater than a fixed value. For example, if the battery voltage is under 9V whereas the normal voltage value is 12V, the bearing unit disables this intuitive restart to preserve the battery.

[0034] FIG. 5 shows a process flow diagram 500 of switching on and off the bearing unit described in FIG. 1 , according to one embodiment. At step 502, ignition key signal is started. The bearing unit continuously checks the signal from the power ignition key in order to switch off the microcontroller and save data when the user shuts of the automobile. This signal level variation can be used to send information or request to the microcontroller.

[0035] Further, logic can be programmed in the microcontroller to translate the variation of this signal level into actions. At step 504, it is determined whether the ignition is toggled twice in a predetermined time. If it is determined not, the process is routed back; else at step 506, the status of the bearing unit is determined. If the status is active, at step 508, the bearing unit is deactivated. If the status is non active, the bearing unit is activated at step 510. Once the status of bearing unit is changed, it is stored in a variable in the system non-volatile memory. This variable is persistent across reboots.

[0036] In another example, signal from the brake lever can be used to activate and deactivate the bearing unit. There are two states signal sending the information that the user presses the brake lever (it is used for example to switch on the vehicle lights). The same principle can be used, in detecting a predetermined sequence of pressing on the brake lever or a combination of several actions. An additional can be added to provide not only the activation and deactivation function but also the possibility to choose between several modes of functioning.

[0037] In various embodiments, the bearing unit can replace existing wheel bearing and speed sensor without any change in the wheel design. There occurs no contact between the speed sensor and the wheel of the automobile, thereby avoiding friction.

[0038] It will be recognized that the above described invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the disclosure. Thus, it is understood that, the invention is not to be limited by the foregoing illustrative details, but it is rather to be defined by the appended claims.