JP2013096397A - Start acceleration assistance device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a start acceleration assistance device which has a simple structure, and can achieve sufficiently high boost pressure during start acceleration.SOLUTION: Between a turbo charger 2 and an engine 3, a high pressure air introduction means 19 is provided which introduces into an intake manifold 14 high-pressure air from an air tank 18 for an airbrake, and during starting and acceleration, the high pressure air introduction device 19 assists the intake of air into the intake manifold 14.

Description

  The present invention relates to a starting acceleration assisting device suitable for a vehicle equipped with a turbocharger, and relates to a starting acceleration assisting device that can obtain a sufficiently high boost pressure during starting and acceleration with a simple configuration.

  A turbocharger rotates a turbine with exhaust gas and compresses air with a compressor linked to the turbine.

  The engine cannot increase the fuel injection amount beyond the fuel injection amount corresponding to the intake air amount from the viewpoint of preventing the generation of black smoke. However, in a vehicle equipped with a turbocharger, the intake air amount of the engine can be increased by increasing the boost pressure with the turbocharger. When the intake air amount increases due to the boost pressure increase, the fuel injection amount can be increased, and a high torque can be output from the engine.

  The turbocharger 2 shown in FIG. 4 is a two-stage turbocharger. The high-pressure exhaust gas discharged from the exhaust manifold 4 of the engine 3 is introduced from the high-pressure exhaust pipe 5 to the turbine 7 of the high-pressure stage turbocharger 6, and the exhaust gas that has become low pressure in the turbine 7 is the turbine 9 of the low-pressure stage turbocharger 8. To be introduced. On the other hand, the air is compressed to a pressure higher than the atmospheric pressure by the compressor 10 of the low-pressure stage turbocharger 8 and sent to the compressor 11 of the high-pressure stage turbocharger 6. In the compressor 11, the air is further compressed to a high pressure, cooled by the intercooler 12, and sent from the high pressure intake pipe 13 to the intake manifold 14 of the engine 3.

  In the EGR device 17, the exhaust gas from the high-pressure exhaust pipe 5 is cooled by the EGR cooler 16 according to the opening degree of the EGR valve 15 and circulated to the high-pressure intake pipe 13.

JP-A-8-260991

  In the turbocharger 2, the impellers built in the turbines 7 and 9 and the compressors 10 and 11, and the rotating shaft connecting the both impellers have inertia, so that the turbocharger 2 shifts rapidly from a low rotation to a high rotation. It is difficult. For this reason, the boost pressure may be delayed in a situation where the boost pressure needs to be quickly increased, such as when starting or accelerating. If the boost pressure is delayed and the intake air amount is insufficient, the fuel injection amount cannot be increased, and the engine output torque will not increase sufficiently, so the vehicle will not be able to start or accelerate quickly and the driving feeling will be impaired. It is. In particular, in the two-stage turbocharger 2, a delay in the rotation speed increase due to inertia is significant, and the increase in the boost pressure is delayed.

  In the intake device disclosed in Patent Document 1, an excess boost pressure is stored in an accumulator tank when the engine rotates at high speed, and the boost pressure is taken out from the accumulator tank at a low rotation time such as when starting acceleration. Then, the intake air amount that cannot be obtained quickly is compensated.

  However, in this intake device, since air is sent to the pressure accumulating tank by a turbocharger compressor, the air pressure in the pressure accumulating tank does not exceed the boost pressure of the compressor. Therefore, the boost pressure of the air that can be taken out from the pressure accumulation tank does not exceed the boost pressure of the compressor when air is stored in the pressure accumulation tank. For this reason, it is not possible to meet the demand for increasing the intake air amount more quickly.

  Further, in this intake device, since a pressure accumulating tank that has not been conventionally added is added, the cost increases with the increase in members, and the layout around the engine becomes complicated.

  Therefore, an object of the present invention is to solve the above-described problems and provide a start acceleration assisting device that can obtain a sufficiently high boost pressure at the start and acceleration with a simple configuration.

  In order to achieve the above object, a starting acceleration assisting apparatus of the present invention is provided with high pressure air introducing means for introducing high pressure air from an air brake air tank into an intake manifold between a turbocharger and an engine. The high pressure air introduction means assists the air intake into the intake manifold.

  The correspondence may be obtained in advance between the front / rear inclination of the vehicle body and the torque required for starting and acceleration, and the assist may be executed when the engine output torque is less than the torque corresponding to the front / rear inclination of the vehicle body.

  The assist may be executed when the forward acceleration of the vehicle body is less than a predetermined lower limit value.

  The assist may be executed when the boost pressure is less than a predetermined lower limit value.

  The assist may be executed when the engine speed is less than a predetermined lower limit.

  The correspondence may be obtained in advance between the boost pressure and the injectable fuel injection amount, and the assist may be executed when the injectable fuel injection amount corresponding to the boost pressure is less than the fuel injection instruction amount.

  The present invention exhibits the following excellent effects.

  (1) It can be realized with a simple configuration.

  (2) A sufficiently high boost pressure can be obtained when starting or accelerating.

1 is a configuration diagram around an engine of a vehicle to which a start acceleration assisting device showing an embodiment of the present invention is applied. It is a flowchart which shows the control procedure at the time of start acceleration in the start acceleration auxiliary | assistance apparatus of this invention. It is a graph which shows the time change of the torque in this invention and a prior art. It is a block diagram around the engine of a conventional vehicle.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, the vehicle to which the start acceleration assisting device 1 of the present invention is applied is equipped with a turbocharger 2. In this embodiment, the turbocharger 2 is a two-stage type. In this vehicle, a high pressure exhaust pipe 5 is connected to an exhaust manifold 4 of the engine 3, and an inlet of a turbine 7 of a high pressure stage turbocharger 6 is connected to the high pressure exhaust pipe 5. The inlet of the turbine 9 of the low-pressure stage turbocharger 8 is connected to the outlet of the turbine 7. The outlet of the turbine 9 is connected to the atmosphere via an exhaust gas processing device (not shown). The inlet of the compressor 10 of the low-pressure stage turbocharger 8 is connected to the atmosphere via an air filter (not shown). The inlet of the compressor 11 of the high-pressure turbocharger 6 is connected to the outlet of the compressor 10, the high-pressure intake pipe 13 is connected to the outlet of the compressor 11 via the intercooler 12, and the intake manifold 14 of the engine 3 is connected to the high-pressure intake pipe 13. Connected. An EGR device 17 having an EGR valve 15 and an EGR cooler 16 is provided between the high pressure exhaust pipe 5 and the high pressure intake pipe 13.

  The start acceleration assisting apparatus 1 of the present invention is provided with high pressure air introduction means 19 for introducing high pressure air from an air brake air tank 18 into an intake manifold 14 between the turbocharger 2 and the engine 3, and the high pressure air at the time of start and acceleration. The introduction means 19 assists the intake of air into the intake manifold 14.

  The air tank 18 for air brakes stores the compressed air for supplying to the air brake which is not shown in figure. Air brakes are conventionally used in vehicles, particularly medium and large vehicles. The air brake air tank 18 stores compressed air by a dedicated compressor (not shown). However, since it is necessary to obtain a large braking force, the air brake 18 is compressed at a pressure higher than the maximum boost pressure that can be realized by the compressor 11 of the high-pressure turbocharger 6. Can store air.

  The high-pressure air introduction means 19 includes an assist pipe 20 connected to the air brake air tank 18 and an assist valve 21 connected to the assist pipe 20 and inserted into the high-pressure intake pipe 13 from the intercooler 12 to the intake manifold 14. Become. The assist valve 21 is provided closer to the intercooler than the connection location of the EGR device 17. A boost pressure sensor 22 that detects the boost pressure is provided between the connection points of the assist valve 21 and the EGR device 17.

  The control unit 23 that controls opening / closing of the assist valve 21 is incorporated as software in an electronic control unit (ECU) that has conventionally performed fuel injection control. The ECU knows the current values of all vehicle parameters (sensor detection values and calculated values) used in the control procedure of FIG. Further, the ECU stores various maps and lower limit values used in the control procedure of FIG.

  Hereinafter, the start and acceleration operations of the start acceleration assisting apparatus 1 of the present invention will be described with reference to FIG.

  The control procedure includes a start / acceleration stage T1, an assist necessity determination stage T2, and an assist execution stage T3.

  In the start / acceleration stage T1, the side brake signal switch, the clutch switch, and the foot brake switch are referred to.

  In step S21, it is determined whether or not the side brake signal switch is off. If the determination is NO, that is, if the side brake signal switch is on, it means that the side brake has been pulled, and the start has not started or is not running, so the process returns to the start. If the determination is YES, that is, if the side brake signal switch is off, it means that the side brake has been released and there is a possibility of starting, or the vehicle is running, so the process proceeds to step S22.

  In step S22, it is determined whether the clutch switch is off. If the determination is NO, that is, if the clutch switch is on, it means that the clutch pedal has been depressed and the start has not started or the gear stage is being changed, so the process returns to the start. If the determination is YES, that is, if the clutch switch is off, the clutch pedal has been depressed, and there is a possibility of starting or accelerating, so the process proceeds to step S23.

  In step S23, it is determined whether the foot brake switch is off. If the determination is NO, that is, if the foot brake switch is on, the brake pedal has been depressed and the start has not started or the vehicle is decelerating, so the process returns to the start. If the determination is YES, that is, if the foot brake switch is off, it is determined that the brake pedal has been depressed, and that it is necessary to respond to start or acceleration in conjunction with the previous determination. Therefore, the process proceeds to the stage T2 for determining the necessity of assisting for starting and acceleration.

  At the stage T2 for determining necessity of assist, the accelerator opening, the number of gear stages, the vehicle speed, the forward acceleration, the forward tilt angle, the boost pressure, the engine rotation speed, and the fuel injection instruction amount are referred to. Based on these vehicle parameters, It is determined whether it is necessary to assist the intake of air into the intake manifold by the high-pressure air introduction means.

[Judgment 1]
The start / acceleration torque map is a map in which the correspondence relationship between the forward inclination angle and the torque required for start and acceleration is set in the map. It is an uphill road when the forward inclination angle is greater than 0, and the larger the forward inclination angle, the greater the required torque. The forward tilt angle is applied to the start / acceleration torque map, and the torque required for start and acceleration is read out. On the other hand, the current engine output torque is calculated from the accelerator opening, the number of gears, and the vehicle speed by a known method. When the current engine output torque is less than the torque required for starting and accelerating, it is determined that assistance is required.

[Decision 2]
When the forward acceleration is less than a predetermined acceleration lower limit value, it is determined that assistance is required in order to increase the forward acceleration quickly.

[Decision 3]
When the boost pressure is less than a predetermined pressure lower limit value, it is determined that assistance is required to quickly increase the boost pressure.

[Decision 4]
When the engine rotation speed is less than a predetermined rotation lower limit value, it is determined that assistance is required in order to quickly increase the engine rotation speed.

[Decision 5]
The boost pressure versus fuel injection amount map is a map in which the correspondence between the boost pressure and the fuel injection amount that can be injected is set in the map. The boost pressure is applied to the boost pressure vs. fuel injection amount map, and the fuel injection amount that can be injected is read out. On the other hand, the fuel injection instruction amount is calculated based on the accelerator opening. When the injectable fuel injection amount is less than the fuel injection instruction amount, it is determined that assistance is required.

  If it is determined that the assist is necessary even if one of the determination results of the determinations 1 to 5 is necessary, the execution of the assist is finally determined. If it is determined that no assist is required, the control procedure is terminated.

  In the assist execution stage T3, the assist valve 21 is opened, and high-pressure air is introduced into the intake manifold 14 from the air tank 18 for air brake. As a result, the boost pressure rises, and the ECU can increase the fuel injection amount.

  When the ECU increases the fuel injection amount based on the accelerator opening, the value of the vehicle parameter referred to in the determinations 1 to 5 is improved. That is, whether the engine output torque reaches the required torque corresponding to the forward tilt angle, the forward acceleration reaches the acceleration lower limit value, the boost pressure reaches the pressure lower limit value, or the engine speed reaches the rotation lower limit value. The fuel injection amount that can be injected corresponding to the boost pressure reaches the fuel injection instruction amount. When the value of the vehicle parameter is thus improved, it is determined that the assist has been achieved. The assist ends and the assist valve 21 is closed. At this time, as the fuel injection amount increases, the exhaust gas amount increases and the rotation of the turbocharger 2 is promoted, so that a sufficient intake air amount can be obtained from the turbocharger 2.

  As a result of the above control, start and acceleration are achieved quickly.

  FIG. 3 shows the time change of torque in the present invention and the prior art.

  As shown in the figure, in the prior art (without assist), the torque rises only immediately after the start of starting, and it takes time to reach a desired torque value. In the present invention, since the assist is executed, the torque rises quickly immediately after the start of starting or immediately after the start of acceleration, and the time required to reach the desired torque value is shortened compared to the conventional case. From this, it can be seen that in the present invention, start / acceleration is quickly achieved.

  According to the start acceleration assisting apparatus 1 of the present invention, the high pressure air introducing means 19 for introducing the high pressure air from the air brake air tank 18 to the intake manifold 14 is provided between the turbocharger 2 and the engine 3, and the high pressure air at the time of start acceleration is provided. Since the introduction means 19 assists the intake of air into the intake manifold 14, start and acceleration can be achieved quickly.

  The start acceleration assisting apparatus 1 according to the present invention does not need to add a new accumulator tank and has a simple configuration as compared with the intake apparatus disclosed in Patent Document 1.

  Since the starting acceleration assisting device 1 of the present invention uses high-pressure air for air braking, a boost pressure sufficiently higher than the intake device of Patent Document 1 that does not exceed the boost pressure of the compressor can be obtained.

  In the present embodiment, the turbocharger 2 is of a two-stage type, but the present invention can also be applied to a single-stage turbocharger.

DESCRIPTION OF SYMBOLS 1 Start acceleration assistance apparatus 2 Turbocharger 3 Engine 14 Intake manifold 18 Air tank for air brake 19 High pressure air introduction means

Claims (6)

  A high-pressure air introduction means for introducing high-pressure air from the air brake air tank to the intake manifold is provided between the turbocharger and the engine so that the high-pressure air introduction means assists the intake of air into the intake manifold at the time of start and acceleration. A starting acceleration assisting device characterized by that.   A correspondence relationship between the front and rear inclination of the vehicle body and the torque required for starting and acceleration is obtained in advance, and the assist is executed when the engine output torque is less than the torque corresponding to the front and rear inclination of the vehicle body. The start acceleration assisting device according to claim 1.   The start acceleration assisting device according to claim 1 or 2, wherein the assist is executed when a forward acceleration of the vehicle body is less than a predetermined lower limit value.   The start acceleration assisting device according to any one of claims 1 to 3, wherein the assist is executed when a boost pressure is less than a predetermined lower limit value.   The start acceleration assisting device according to any one of claims 1 to 4, wherein the assist is executed when an engine rotation speed is less than a predetermined lower limit value.   A correspondence relationship between the boost pressure and the injectable fuel injection amount is obtained in advance, and the assist is executed when the injectable fuel injection amount corresponding to the boost pressure is less than the fuel injection instruction amount. The start acceleration assisting device according to any one of claims 1 to 5.

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