A MODIFIED TRIGGER WHEEL, A CONTROLLER AND METHOD FOR A PRIME MOVER OF A VEHICLE

2. Applicants: a. Name: Robert Bosch Engineering and Business Solutions

Private Limited

Nationality: INDIA

Address: 123, Industrial Layout, Hosur Road, Koramangala, Bangalore - 560095, Karnataka, India b. Name: Robert Bosch GmbH

Nationality: GERMANY

Address: Feuerbach, Stuttgart, Germany

Complete Specification:

The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed. Field of the invention:

[0001] The present invention relates to a modified trigger wheel, a controller and a method for a prime mover of a vehicle.

Background of the invention:

[0002] A crankshaft trigger wheel commonly used in vehicle systems are 36-2, 24- 2, 12-3, etc. A rotary machine such as generator or Integrated Starter Generator (ISG) is often coupled with crankshaft of an engine of the vehicle. In case of Belt driven Starter Generator (BSG) systems, the rotary machine is coupled to the engine with belt. Further, inductive type crankshaft sensors are widely used, which does not provide rotation direction information, and stop position calculated by controller using the inductive type sensor is not reliable and hence not used for quick start. In addition, a minimum and maximum engine speed support required is 40 RPM and 12000RPM respectively. Alternatively, engine speed gradient, manifold pressure-based techniques are widely used for engine position detection.

[0003] According to a prior art US20030037607 an encoded crank position sensor is disclosed. A target wheel for providing timing information for a crankshaft in an internal combustion engine, the target wheel comprising a substantially circular member having a plurality of teeth, the teeth having variable widths, and the teeth having rising edges distributed in a non-uniform fashion and falling edges distributed in a uniform fashion, where the target wheel provides speed and timing information for multiple internal combustion engine configurations.

Brief description of the accompanying drawings:

[0004] An embodiment of the disclosure is described with reference to the following accompanying drawings,

[0005] Fig. 1 illustrates a block diagram of a system and a controller for a vehicle, according to an embodiment of the present invention, and

[0006] Fig. 2 illustrates a method for operating a prime mover ofthe vehicle, according to the present invention. Detailed description of the embodiments:

[0007] Fig. 1 illustrates a block diagram of a system and a controller for a vehicle, according to an embodiment of the present invention. The vehicle comprises a prime mover for providing motive power, a primary shaft coupling the prime mover to a drivetrain of the vehicle, a position sensor 116 to monitor a mechanical position of the primary shaft. The prime mover is any one of a rotary electric machine 118 with a rotor shaft as the primary shaft, and a combustion engine with crankshaft as the primary shaft coupled with the rotary electric machine 118 for assistance. Both the rotary electric machine 118 and the position sensor 116 are connected/interfaced to/with the controller 120, characterized in that, the controller 120 configured to receive, upon rotation of the primary shaft, a position signal from the position sensor 116 positioned to monitor/sense a modified trigger wheel 114. The modified trigger wheel 114 is coupled to the primary shaft either directly or through but not limited to a belt. The controller 120 processes the position signal and determines a tooth pattern of the modified trigger wheel 114. The controller 120 determines a parameter in dependence of the determined tooth pattern. The parameter is related to at least one of the combustion engine and the rotary electric machine 118. The rotary electric machine 118 is connected to the controller 120 through an inverter circuit 128.

[0008] According to the present invention, the controller 120 is provided with necessary signal detection, acquisition, and processing circuits along with the sensors (if required). The controller 120 is a control unit which comprises memory element 122 such as Random Access Memory (RAM) and/or Read Only Memory (ROM), Analog-to-Digital Converter (ADC) and a Digital-to- Analog Convertor (DAC), clocks, timers, counters and at least one processor (capable of implementing machine learning) connected with each other and to other components through communication bus channels. The memory element 122 is prestored with logics or instructions or programs or applications or modules/models and/or threshold values, preset tooth patterns which is/are accessed by the at least one processor as per the defined routines. The internal components of the controller 120 are not explained for being state of the art, and the same must not be understood in a limiting manner. The controller 120 may also comprise communication units to communicate with an external computing device such as the cloud, a remote server, etc., through wireless or wired means such as Global System for Mobile Communications (GSM), 3G, 4G, 5G, Wi-Fi, Bluetooth, Ethernet, serial networks, and the like. The controller 120 is implementable in the form of System-in-Package (SiP) or System-on-Chip (SOC) or any other known types. Further, the controller 120 is the Vehicle Control Unit (VCU), the Body Control Unit/Module (BCU/BCM), the Engine Control Unit (ECU) or combination thereof.

[0009] In accordance to an embodiment of the present invention, the controller 120 is applicable to be used for two-wheeler such as motorcycles, scooters, e-bikes, three wheelers such as auto -rickshaws, a four wheeler such as cars, multi wheel vehicles and other vehicles such as water sports vehicles and snow mobiles.

[0010] According to an embodiment of the present invention, the parameter is at least one selected from a group comprising a direction of rotation of the primary shaft, a knocking of the engine and an electrical position of the rotary electric machine 118. The electrical position is a position of an electrical period in a phase voltage signal of the rotary electric machine 118. The position is determined based on a fixed relationship between the phase voltage signal and the position signal.

[0011] In order to determine the electrical position, the controller 120 first detects the tooth pattern on the position signal. Once the tooth pattern is detected, then the controller 120 correlates the tooth pattern with the corresponding known electrical position in the electrical period of the phase voltage signal. Further, once the electrical position is determined, the controller 120 then calculates the torque required to start the prime mover and hence closed loop operation for the rotary electric machine 118 is achieved faster. The prime mover is either the rotary electric machine 118 or the combustion engine. The controller 120 then drives the rotary electric machine 118 as per the calculated torque. The time taken till the torque calculation with known electrical position and actuation is very less, i.e. within time taken for first tooth pattern detection itself, hence the electric position is determined very quick.

[0012] According to an embodiment of the present invention, the controller 120 is configured to determine electrical position of the rotary electric machine 118 using the phase voltage signal generated by the rotary electric machine 118. However, before the electrical position is determined, the controller 120 is configured to control the inverter circuit 128 to rotate the prime mover in open loop mode for detecting the tooth pattern of the modified trigger wheel 114. The controller 120 actuates the rotary electric machine 118 and starts rotating the primary shaft of the prime mover. When the primary shaft starts rotating, i.e. upon rotation of the primary shaft, the tooth pattern of the modified trigger wheel 114 is detected and consequently electrical position of the phase voltage signal is deduced, which is then used to calculate the actual torque needed to control the rotary electric machine 118. The controller 120 then applies the calculated torque and starts /drives the prime mover.

[0013] According to an embodiment of the present invention, the controller 120 is configured to detect at least one of the direction of rotation (reverse or forward) of the crankshaft, the knocking in the engine and the electric position of the rotary electric machine 118 based on the position signal received from the position sensor 116 (i.e. the tooth pattern determined from the position signal). Consider a system 130 where the prime mover is the engine, and the primary shaft is the crankshaft. In order to detect the direction of rotation of engine, the controller 120 is configured to detect a first tooth pattern and a second tooth pattern. When a first tooth pattern is detected then the direction is considered as reverse. Similarly when a second tooth pattern is detected, then the direction is considered to be forward. The teeth period after identification of a Top Dead Center (TDC) are used to analyze engine speed profile for knock detection. In order to detect knocking, the controller 120 is configured to observe disturbances on engine speed calculated after compression TDC. Normally 36-2 or 24-2 type conventional trigger wheels are used. The tooth angle is either 10 degrees or 15 degrees and causes difficult to capture the oscillations reliably. With the modified trigger wheel 114, both low pulse and high pulse period are used by the controller 120. And there is already a fixed relationship between low and high pulse. In case of knocking, this relationship is disturbed and easier to capture the effect because of knocking.

[0014] In accordance to an embodiment of the present invention, the modified trigger wheel 114 for determination of position of the primary shaft of the prime mover in the vehicle is provided. The modified trigger wheel 114 comprises multiple tooth on its periphery with equal tooth period and a reference gap (one tooth gap or two tooth gap, etc.), characterized in that, the multiple tooth are of at least three different widths within respective tooth periods of equal length. The multiple tooth are arranged in a pattern to detect at least one of the directions of rotation of the primary shaft, the knocking of the engine and the electrical position of the rotary electric machine 118 coupled to the primary shaft. The trigger wheel 114 also relates to an encoder wheel which comprises markings and gaps instead of the tooth. The trigger wheel 114 is replaceable with encoder wheel as well.

[0015] According to an embodiment of the present invention, the at least three widths of multiple tooth used in the modified trigger wheel 114 comprises a first width, a second width and a third width or more, each of which have equal teeth period of “L” (also known as tooth segment). For example and not limited to the same, the first width is denoted by “A” and corresponds to tooth width designed in 50:50 (LOW/HIGH) ratio within the teeth period “L”, i.e. half of the teeth period is tooth and remaining is gap. The second width is denoted by “B” and corresponds to tooth width designed with 25:75 (LOW/HIGH) ratio within the teeth period “L”, i.e., 25% of the teeth period “L” is tooth and 75% is gap. Similarly, the third width is denoted by “C” and corresponds to tooth width designed in manner 75:25 (LOW/HIGH) ratio within the teeth period “L”, i.e. 75% of “L” is tooth and remaining 25% is gap. A first pattern of the tooth comprises ABAC.... A second pattern of the tooth comprises ACAB. Similarly other combinations of different patterns are possible such as but not limited to ACBA, ABCA, ABBC, ACCB, etc. Once the modified trigger wheel 114 is designed and coupled to the crankshaft, the tooth pattern changes based on the direction of rotation of the crankshaft. The tooth width type need not be limited to only three different types like, A, B and C. And also LOW/HIGH ratio need not be limited to 50:50, 75:25 or 25:75.

[0016] According to the present invention, a working of the present invention is envisaged and the same must not be understood in limiting manner. The vehicle considered comprises engine as the prime mover and crankshaft as the primary shaft. Before proceeding with the explanation, the signals from conventional trigger wheel is explained through a first graph 100. A first signal 102 represents cut-out view of the conventional trigger wheel with equal teeth period and equal tooth width. A second signal 104 is the position signal (also referred as crank signal for engine) detected by position sensor 116. Now consider the modified trigger wheel 114 with 24-2 configuration with tooth pattern as ABAC. With reference to a second graph 110, the third signal 106 represents the cut-out view of the modified trigger wheel 114 as proposed in the present invention. The fourth signal 108 is the position signal detected by the position sensor 116 for the modified trigger wheel 114. A fifth signal 112 is one of the phase voltage signals of rotary electric machine 118 after processing an actual phase voltage signal (not shown). The dotted vertical lines indicate the teeth period and corresponding tooth width. It can be seen that the falling edge and rising edge of the of the fifth signal 112 (the voltage signal) are in sync with the falling/rising edge of the fourth signal 108. However, it may happen that the fourth signal 108 and the fifth signal 112 are offset by some degrees, in which case the controller 120 is configured to adjust the offset after receiving the respective signals.

[0017] Now, consider the modified trigger wheel 114 is setup in the vehicle such as the motorcycle. A rider switches ON the vehicle, after which the controller 120 triggers the activation of the rotary electric machine 118 through the inverter circuit 128, which results in rotation of the crankshaft in open loop, i.e. without any information of the mechanical or electrical position. The rotary electric machine 118 is used, as for example, an Integrated Starter Generator (ISG) which is coupled to the crankshaft of the engine. Once the crank signal is received by the controller 120, the controller 120 detects the tooth pattern. If the tooth pattern is detected to be ACAB then it is determined to be reverse rotation. Similarly, if the tooth pattern is detected to be ABAC, then forward rotation is determined. Further, if an incorrect rotation is detected, the controller 120 is configured to correct the direction of rotation as well. Assuming that the correct direction of rotation is detected, then the controller 120 co-relates the tooth pattern with the electrical period of the phase voltage signal and identifies the electrical position of the rotary electric machine 118. Once the electrical position is identified, the controller 120 calculates the exact amount of torque needed to start the engine from rest and then starts and drives the engine.

[0018] According to an embodiment of the present invention, a prime mover management system 130 for the vehicle is disclosed. The vehicle comprises the primary shaft coupling the prime mover to the drivetrain of the vehicle, and a position sensor 116 to monitor a mechanical position of the primary shaft. The prime mover is any one of the rotary electric machine 118 with the rotor shaft as the primary shaft, and the combustion engine with crankshaft as the primary shaft coupled with the rotary electric machine 118. The controller 120 connected to both of the rotary electric machine 118 via through the inverter circuit 128 and the crankshaft position sensor 116, characterized in that, the modified trigger wheel 114 coupled to the primary shaft of the prime mover, and the controller 120 configured to receive, upon rotation of the primary shaft, the position signal from the position sensor 116 positioned/located to monitor/sense the modified trigger wheel 114, process the position signal and determine the tooth pattern of the modified trigger wheel 114, and determine the parameter in dependence of the determined tooth pattern. The parameter is related to at least one of the combustion engine and the rotary electric machine 118. The parameter is at least one selected from a group comprising a direction of rotation of the primary shaft, the knocking of the engine and the electrical position of the rotary electric machine 118.

[0019] Further, when the prime mover is the combustion engine, the controller 120 configured to calculate the torque required to start the combustion engine from the determined position of the electrical period, and drive the rotary electric machine 118 according to the calculated torque and start/drive the combustion engine.

[0020] In another example, the modified trigger wheel 114 is disclosed. For a 6 pole pairs based rotary electric machine 118, in one rotation of rotor there will be 6 electrical periods on a phase/voltage signal. A three/multi-phase rotary electric machine 118 is also possible to be used and not limited to the same. The modified trigger wheel 114 is usable as a replacement of the existing/conventional trigger wheel. For example, a 24-2 conventional trigger wheel is replaceable with the modified trigger wheel 114. Every edge/pulse on the modified trigger wheel 114 gives position information about electrical system. The modified trigger wheel 114 and rotary electric machine 118 with 6 pulses is equivalent to pole pairs is the simplest way to detect electrical position. The modified trigger wheel 114 is comparable and replaceable with corresponding equivalent conventional trigger wheel, such as 24-2. The controller 120 receives 22 periods on the voltage signal. At least three unique pulses (including reference gap) are designed on the modified trigger wheel 114. There is possibility of more unique patterns. The fixed pattern on voltage signal in an electrical pulse. The offset between mechanical and electrical system is adjustable. During start, the controller 120 is able to detect the electrical position with two or less periods on the phase voltage signal. After electrical position detection, the information is used by the controller 120 to strategically operate the rotary electric machine 118. No additional sensors are required to determine the electrical position in case mild hybrid or EV system to control motor operation. The cost of system is also reduced. [0021] In accordance to an embodiment of the present invention, the controller 120 is configured to determine electrical position for the rotary electric machine 118 (as the prime mover) in an Electric Vehicle (EV). Consider an electric Auto-rickshaw as the vehicle. The rotor shaft of the rotary electric machine 118 is equipped/fit with the modified trigger wheel 114. Further, the position sensor 116 is placed adjacent to the modified trigger wheel 114. The controller 120 first energizes the rotary electric machine 118 in open loop, and with rotation the position signals from the position sensor 116 are measured. The controller 120 determines the mechanical position, and then determines the electrical position by co-relating the mechanical position with the phase voltage signal of the rotary electric machine 118. Once the electrical position is determined, the controller 120 is able to start with the required torque and then drive the EV accordingly.

[0022] In accordance to an embodiment of the present invention, the rotary electric machine 118 is an Integrated Starter Generator (ISG) or other type of rotary electric machines 118 known in the art.

[0023] Fig. 2 illustrates a method for operating the prime mover of the vehicle, according to the present invention. The vehicle comprises the primary shaft coupling the prime mover to the drivetrain of the vehicle, and the position sensor 116 to monitor the mechanical position of the primary shaft. The prime mover is any one of the rotary electric machine 118 with the rotor shaft as the primary shaft and the combustion engine with crankshaft as the primary shaft coupled with the rotary electric machine 118. The rotary electric machine 118 and the position sensor 116, are connected to the controller 120. The method is characterized by plurality of steps of which a step 202 comprises receiving, upon rotation of the primary shaft, the position signal from the position sensor 116 positioned/located for monitoring the modified trigger wheel 114. The modified trigger wheel 114 is coupled to the primary shaft either directly or indirectly such as but not limited to through belt. A step 204 comprises processing the position signal and determining the tooth pattern of the modified trigger wheel 114. A step 206 comprises determining the parameter in dependence of the determined tooth pattern. The parameter is related to at least one of the combustion engine and the rotary electric machine 118. The parameter is at least one selected from a group comprising the direction of rotation of the primary shaft, the knocking of the engine and the electrical position of the rotary electric machine 118.

[0024] When the prime mover comprises the combustion engine, a step 208 comprises calculating the torque required for starting the combustion engine from the determined electrical position of the rotary electric machine 118. A step 210 comprises driving the rotary electric machine 118 according to the calculated torque and starting/driving the combustion engine.

[0025] According to the present invention, the modified/improved trigger wheel 114 for engine of the vehicle is disclosed. For systems 130 with ISG, electric position detection is faster. The position estimation complexity in the existing software is reduced to great extent. Further, switching from open loop control (when position is not determined) to closed loop control (when position is known) for ISG system 130 is faster. For mild-hybrid systems, electrical machine is used to assist the internal combustion engine, detection of electrical position is possible with the modified trigger wheel 114 is coupled to crankshaft/ primary shaft. Additional sensors to detect position of the rotary electric machine 118 is saved, cost of the system 130 is reduced. Also for EV application, if the phase voltage signal is analyzed with the position signal, , then electrical position of the rotary electric machine 118 is derivable. In such systems 130 also several sensors are also used to determine the electrical position, which is eliminated and thus cost of the system 130 is further reduced. The reverse rotation detection is possible with unidirectional sensor, and therefore no need for expensive bi-directional sensors. Further, the controller 120 is able to accurately calculate the stop position, which is then used for engine restart. The present invention also enables sensor less knock detection. The tooth pattern (profile or sequence) after TDC is used efficiently to detect knock, thus the modified trigger wheel 114 is used as cost efficient sensor less knock detection solution in automotive systems. The implementation of the present invention has no impact on an existing Engine Management System software or logics, as the same modified trigger wheel 114 is usable for engine position and engine speed calculation without any change in logic.

[0026] It should be understood that the embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.