Engine start system

Abstract

To provide an engine start system capable of preventing excessive load to a starter motor.SOLUTION: When a user issues a clutch start cancel command, an engine starting system 10 allows a starter 12 to start with a clutch engaged when a foot brake 22 is ON or an engine speed is equal to or lower than a certain level.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This specification discloses an engine starting system that starts an engine with a starter motor.

Background Art

[0002] A manual transmission vehicle (hereinafter referred to as a manual vehicle) is set with a clutch start function. The clutch start function is a function that permits starting of the engine only when the clutch connection is released. When the clutch start function is effective, the starter motor does not operate unless the ignition switch is turned ON while the clutch pedal is depressed (i.e., the clutch connection is released).

[0003] By the way, some vehicles have a clutch start cancel (hereinafter abbreviated as "CSC") function for canceling this clutch start function. For example, Patent Document 1 discloses a vehicle having a CSC switch. When the CSC switch is turned ON in the vehicle described in Patent Document 1, the starter motor operates if the ignition switch is turned ON even when the clutch is engaged.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, in the conventional CSC function proposed in Patent Document 1 and the like, when the CSC switch is turned on, the starter can be driven with the clutch engaged at any timing. However, depending on the vehicle situation, the load on the starter motor may increase. For example, when starting the starter motor with the clutch engaged while the vehicle is slipping downhill on a slope, the load on the starter motor increases.

[0006] Therefore, this specification discloses an engine starting system that can prevent an excessive load on the starter motor.

Means for Solving the Problems

[0007] The engine starting system disclosed in this specification is characterized in that when the clutch start cancel is instructed by the user, if the foot brake is on or the engine speed is below a certain level, starting of the starter with the clutch engaged is permitted.

Advantages of the Invention

[0008] According to the engine starting system disclosed in this specification, an excessive load on the starter can be prevented.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0010] Hereinafter, the configuration of the engine starting system 10 will be described with reference to the drawings. FIG. 1 is a block diagram showing the electrical configuration of the engine starting system 10. The engine starting system 10 is provided in an MT vehicle equipped with an engine 14 (not shown) as a power source.

[0011] The starter 12 is a motor for starting the engine 14. The torque of the starter 12 is transmitted to the output shaft of the engine 14 via a gear. The ignition switch 16 is a switch operated by the user when starting the engine 14. The ignition switch 16 is provided, for example, on the instrument panel. When a predetermined condition is satisfied, the starter 12 operates by long-pushing the ignition switch 16.

[0012] Also, the engine starting system 10 of this example has a clutch start function. The clutch start function is enabled unless there is a special instruction from the user. The clutch start function is a function that permits the operation of the starter 12 only when the clutch connection is released. Therefore, usually, when starting the engine 14, the user long-pushes the ignition switch 16 while depressing the clutch pedal 18 with the parking brake 24 enabled. Thereby, the starter 12 operates and the engine 14 starts. By providing such a clutch start function, unintended sudden starts and the like can be effectively prevented.

[0013] However, depending on the vehicle's situation, there may be a case where the clutch start function needs to be disabled. For example, in off-road driving, due to special driving such as crossing obstacles, the engine 14 often stops, and there are many situations where it is desired to restart the engine 14 with the clutch engaged. Therefore, the engine starting system 10 in this example also has a CSC function that can start the engine 14 with the clutch engaged. The CSC function is enabled by briefly pushing the CSC switch 20 while stepping on the foot brake pedal (that is, while enabling the foot brake 22). When the CSC function is enabled, engine starting with the clutch engaged is permitted. However, depending on the vehicle's situation, such engine starting may not be desirable. Therefore, in this example, even when the CSC function is enabled, the starter 12 is not operated unless a predetermined condition is satisfied. The conditions for operating this starter 12 will be described later.

[0014] The EFI-ECU 26 is an ECU that controls fuel injection necessary for ignition of the vehicle engine 14. The EFI-ECU 26 outputs the engine speed to the determination ECU 30 as necessary. The VSC-ECU 28 is an ECU that controls the brakes and the power of the engine 14 in order to improve the stability of the vehicle. The VSC-ECU 28 also performs hill start assist control (hereinafter referred to as "HAC"). HAC is a function that maintains the braking force even when the foot brake pedal is temporarily released on a slope and assists the starting operation.

[0015] The determination ECU 30 controls the drive of the starter 12. The determination ECU 30 collects the enabled / disabled states of the clutch start function and the CSC function, the operating state of the foot brake 22, the operating state of the parking brake 24, and the engine speed, and controls the drive of the starter 12 based on this information. Also, as necessary, it instructs the VSC-ECU 28 to disable the HAC.

[0016] Next, in such an engine starting system 10, the activation of the CSC function and the engine starting procedure will be described with reference to FIG. 2. As described above, unless there is a special instruction from the user, the clutch start function is activated and the CSC function is deactivated. In this state, when the user short-presses the CSC switch 20 while depressing the foot brake pedal (Yes in S10), the CSC function is activated (S12). Also, when the CSC function is activated, the determination ECU 30 instructs the VSC-ECU 28 to deactivate the HAC.

[0017] In a state where the CSC function is activated, further, when the user long-presses the ignition switch 16 while depressing the foot brake pedal (i.e., with the foot brake 22 ON) (Yes in S14), even if the clutch is engaged, the starter 12 operates (S24). However, depending on the situation, operating the starter 12 may impose an excessive load on the starter 12. Therefore, the determination ECU 30 permits the operation of the starter 12 only when several conditions are met.

[0018] For example, when the engine speed exceeds a pre-specified reference speed (No in S16), the starter 12 does not operate. This is to protect the starter 12. That is, when the vehicle is slipping downhill on a slope or the like, driving the starter 12 during engine rotation increases the cranking impact, and in some cases, the starter 12 may fail. Therefore, the operation of the starter 12 is permitted only when the engine speed is low.

[0019] Also, when the foot brake 22 is OFF (No in S14), the starter 12 does not operate. This is to prevent cranking during engine rotation. That is, since there is a delay in the engine speed detected by the EFI-ECU 26, the exact engine speed cannot be detected at the beginning of the vehicle's creep. As a result, if judged only by the engine speed, the starter 12 may operate during engine rotation. To avoid such problems, in this example, the operation of the starter 12 is permitted only when the foot brake 22 is ON.

[0020] Note that if the engine speed can be detected in real time without delay, the monitoring of the foot brake 22 may be omitted. Conversely, if the state of the foot brake 22 can be accurately detected, the monitoring of the engine speed may be omitted.

[0021] Also, when the engine 14 has exploded (Yes in S18), the starter 12 is not operated. If the starter 12 is operated at the engine speed after the engine 14 has exploded, the cranking impact will increase, and the starter 12 may fail. Therefore, in this example, when the engine 14 has exploded, the starter 12 is not operated.

[0022] Also, in this example, the elapsed time since the previous drive of the starter 12 is counted as the stop duration, and when this stop duration is less than the specified reference stop time (No in S20), the starter 12 is not operated. This is to prevent the starter 12 from becoming excessively hot. That is, as shown in FIG. 3, when the ON / OFF of the starter 12 is repeated within a short time, the internal temperature of the starter 12 gradually increases. And in some cases, the internal temperature of the starter 12 exceeds the allowable temperature Tmax, and the starter 12 fails. To prevent such overheating of the starter 12, in this example, when the stop duration is less than the reference stop time, the operation of the starter 12 is prohibited to ensure the cooling period of the starter 12.

[0023] Also, in this example, even when the parking brake 24 is ON (No in S22), the starter 12 is not operated. If the starter 12 is operated when the parking brake 24 is ON, a locked current may flow through the starter 12, and the starter 12 may malfunction due to overheating. Therefore, in this example, when the parking brake 24 is ON, the starter 12 is not operated. Further, although not shown in FIG. 2, the driving of the starter 12 may also be prohibited when a communication abnormality occurs between ECUs.

[0024] On the other hand, when the foot brake 22 is ON, the engine speed is less than the reference speed, the engine 14 is OFF, the stop duration is equal to or longer than the reference stop duration, and the parking brake 24 is OFF, the determination ECU 30 operates the starter 12 (S24). The starter 12 continues to operate during the period when the ignition switch 16 is pushed (i.e., the period when the answer in S28 is No). If the engine 14 starts due to the operation of the starter 12, the user releases the ignition switch 16. When the ignition switch 16 is released (Yes in S26), the driving of the starter 12 stops (S30).

[0025] Also, the determination ECU 30 counts the elapsed time since the start of operation of the starter 12 as the operation duration, and when this operation duration becomes equal to or longer than the allowable operation time (Yes in S26), the starter 12 is forcibly stopped (S28). This is to prevent overheating of the starter 12. That is, when the vehicle cannot move forward by cranking due to a curb or the like, a locked current flows through the starter 12. If the locked current continues to flow for a long time, the temperature of the starter 12 rises, and the starter 12 may malfunction. Therefore, when the operation duration becomes equal to or longer than the allowable duration, the operation of the starter 12 is forcibly stopped.

[0026] As described above, even when the CSC function is enabled, the operation of the starter 12 can be effectively prevented by allowing the operation of the starter 12 only when specific conditions are met. Note that the configurations described so far are examples, and other configurations may be changed as long as the configuration described in claim 1 is included. For example, in the above description, in addition to the engine speed and the foot brake, the ON / OFF state of the engine, the duration of the starter stop, the ON / OFF state of the parking brake, and the operation duration are monitored, and the operation of the starter 12 is prohibited or stopped according to the monitoring results. However, if the engine speed or the state of the foot brake is monitored, the monitoring of other conditions may be omitted.

Description of Reference Numerals

[0027] 10 Engine starting system, 12 Starter, 14 Engine, 16 Ignition switch, 18 Clutch pedal, 20 CSC switch, 22 Foot brake, 24 Parking brake, 26 EFI-ECU, 28 VSC-ECU, 30 Judgment ECU.

Claims

【Claim 1】 An engine starting system, characterized in that when a clutch start cancel is instructed by a user, starting of a starter in a state where the clutch is engaged is permitted if the foot brake is ON or the engine speed is equal to or lower than a certain level.

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