JP2778866B2 - In-vehicle turbo compound engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust turbocharger type engine which can be widely used for two-cycle and four-cycle diesel engines mounted on general vehicles, cargo handling machines, construction machines, special vehicles and the like. The present invention relates to a turbo compound engine having a supercharging system, and more particularly to an improvement in connection / disconnection control of a hydraulic connection / disconnection clutch for selecting an operation mode.

[0002]

2. Description of the Related Art As shown in FIG. 5, a conventional turbo compound engine having an exhaust turbocharger has variable stationary blades outside a turbine rotor blade 16 in a turbine portion of an exhaust turbocharger 14. A variable nozzle 18 is arranged on the circumference, and a drive ring 17 for changing the opening of the variable nozzle 18 is provided.
Is connected to the variable nozzle 18 via a link.

[0003] The exhaust turbocharger 14 is connected to the crankshaft 10 of the engine 20 via a power transmission system having a reduction gear train 11. This reduction gear train 11 includes an exhaust turbocharger 14
In the power transmission between the motor and the crankshaft 10, the power transmission system is configured to have two parallel gear trains. Between these gear trains, a first hydraulic clutch 12a, a second hydraulic clutch 12b, which can be hydraulically connected and disconnected by an engine rotation speed signal,
A first one-way clutch 13a and a second one-way clutch 13b respectively connected to the hydraulic clutches 12a and 12b in series are interposed. The two one-way clutches 13a and 13b are connected to the exhaust turbocharger 1 via the gear train 11.
The power transmission directions between 4 and the crankshaft 10 are configured to be opposite to each other. In other words, the directions of the arrows of the one-way clutches 13a and 13b in the drawings indicate the power transmission direction, and the power is not transmitted in the direction opposite to the arrow.

[0004] Hydraulic clutches 12a, 12 interposed in a reduction gear train 11 for connecting the exhaust turbocharger 14 and the crankshaft 10 to each other.
b is an operation mode of the engine 20 and the exhaust turbocharger 14, that is, a mechanical drive mode (hereinafter, referred to as an “MD mode”) in which the engine 20 drives the exhaust turbocharger 14, There are three operation modes: a turbo compound mode in which turbine exhaust energy is recovered to the side 20; and a free turbo mode (hereinafter, referred to as “FT mode”) in which there is no mechanical connection between the engine 20 and the exhaust turbocharger 14. The operation is selectively performed by turning on and off the hydraulic clutches 12a and 12b.

That is, in the MD mode, the first hydraulic clutch 12a is turned on to drive the exhaust turbocharger 14 by the engine 6, and in the FT mode, the first and second hydraulic clutches 12a and 12b are operated. Both are turned off to perform free turbo supercharging, and the second hydraulic clutch 12b is turned on to perform a turbo compound mode, that is, power recovery via the one-way clutch 13b.

The ON / OFF control of each hydraulic clutch in the selection of each mode described above is performed based on the engine speed.

In FIG. 5, reference numeral 21 denotes an exhaust pipe, reference numeral 22 denotes an air supply cooling pipe, reference numeral 19 denotes an air supply pipe, and reference numeral 15 denotes a compressor.

[0008]

By the way, as described above, in the conventional turbo compound engine, the FT
Mode and the MD mode are switched based on the engine speed.
It is in D mode. For this reason, the following problems occur in the vehicle-mounted engine. (1) Since the entire MD gear train must be driven by the starter, the load on the starter increases, the cranking speed decreases, and the startability deteriorates. (2) Since the load at the time of idling increases, fuel efficiency deteriorates. (3) A high-speed gear sound is heard when idling. (4) When the vehicle starts accelerating, start in MD mode and start FT in the middle
Since the point at which the mode is switched is always at a constant rotational speed, the mode is switched regardless of the state of the gear stage of the transmission at that time. Therefore, in the MD mode,
When a shift (for example, shifting from the first gear to the second gear) is performed,
Due to the decrease in the exhaust energy, the torque for driving the exhaust turbocharger increases, and the engine speed decreases significantly.

Then, when the engine speed increases again after the shift, the turbocharger must first be accelerated, and this inertial acceleration torque delays the rise of the engine speed after the shift.

That is, if a shift is performed in the MD mode, the rise of the engine speed is delayed immediately after that, causing a problem such as poor vehicle transient response. That is, in FIG. 4 (FIG. 4 shows the time on the horizontal axis and the rotational speed, engine speed, and vehicle speed of the exhaust turbocharger on the vertical axis), the vehicle speed is changed by a shift performed after a while after starting. increasing speed as shown by line E in line E 'shown by a dotted line is significantly reduced, the time t _b required to reach any vehicle speed V ₀ becomes larger. Note that the rotation speed G and the engine rotation speed F of the exhaust turbocharger G ′ and F ′ and the speed increase thereof are significantly reduced with the shift.

As a countermeasure, FT during idling operation
Mode, and turn the clutch
It is conceivable to set the mode to N and switch to the MD mode. However, since there is a response delay in the hydraulic clutch, switching from the FT mode to the MD mode is not performed promptly,
There is a delay in increasing the rotation speed of the exhaust turbocharger, and it takes time to increase the engine rotation speed. In other words, a delay in switching from the idling FT mode to the starting MD mode causes problems such as temporary generation of exhaust smoke and poor transient response.

This point will be described in more detail. For example, in the case of an engine with an automatic transmission, referring to FIG. 2B, FIG. 2B shows a graph in which the horizontal axis represents time, the vertical axis represents engine speed, exhaust turbocharger speed, This shows the clutch state and the clutch oil pressure.

First, the driver puts the shift lever of the automatic transmission in the N (neutral) range. At this time, the clutch oil pressure flowing into the hydraulic clutch is low as shown by the line D ', and therefore, the hydraulic clutch is in the OFF state as shown by the line C', and therefore the engine is in the FT state.
In mode. This improves idling fuel efficiency while the vehicle is stopped.

Next, the driver puts the shift lever into the D (drive) range with the intention of starting the vehicle, but the engine speed is still at the idling speed.

On the other hand, the switching between the FT mode and the MD mode is performed based only on the engine speed. When the engine is idling (for example, at 800 rpm), the FT mode is selected. For example, 850r.
pm).

Therefore, when the accelerator pedal is depressed to start the vehicle in this state, the mode is not immediately switched from the FT mode to the MD mode, and a rise in the rotational speed of the exhaust turbocharger is delayed. It takes time to increase the rotation speed.

That is, a delay in switching from the FT mode to the MD mode at the time of starting causes an increase in the time [t _b in FIG. Is bad.

In FIG. 2B, the horizontal axis represents time, the line A ′ represents the relationship between the engine speed (vertical axis) and the vehicle speed, and the line D ′.
Represents the relationship between the rotational speed (vertical axis) of the exhaust turbocharger and the vehicle speed, and lines C ′ and D ′ represent ON and OFF of the hydraulic clutch, respectively.
The relationship between the OFF state, the state of the clutch hydraulic pressure, and the vehicle speed is shown.

The present invention is intended to solve such a problem. In a turbo compound engine, as an input signal to a controller of a hydraulic disconnecting clutch for setting the engine to an MD mode and an FD mode. In addition to the engine speed signal, by inputting the position signal of the shift lever of the vehicle or the gear position position signal, the hydraulic connection / disconnection clutch is turned off regardless of the engine speed when the engine is started, and the engine is set to the FT mode. It is an object of the present invention to provide an on-board turbo compound engine which sets and sets the engine to the MD mode by turning on a hydraulic connection / disconnection clutch in a low engine speed range to improve vehicle transient response.

[0020]

In order to achieve the above object, a vehicle-mounted turbo compound engine according to the present invention is a turbo compound engine mounted on a vehicle,
A supercharging system including an exhaust turbocharger and a reduction gear train including two parallel gear trains for connecting the exhaust turbocharger to the crankshaft of the engine; One of the parallel gear trains is configured as a gear train for driving the exhaust turbocharger from the crankshaft of the engine, and the other is configured as a gear train for driving the crankshaft of the engine from the exhaust turbocharger side. In addition, a one-way clutch that can transmit power in the driving direction and does not transmit power in the opposite direction and a hydraulic clutch that can be connected and disconnected are inserted into each gear train, and mechanical control is performed by controlling the connection and disconnection of each hydraulic clutch. Drive mode, turbo compound mode and free turbo mode
One of the two operation modes can be selectively performed, and the connection / disconnection control of each of the hydraulic clutches is controlled by a shift lever position signal or a gear position signal of a transmission of the vehicle, a rotation speed of the engine, It is characterized by being performed based on.

[0021]

With the above-described turbo-compound engine of the present invention, the engine is set to the FT mode when the engine is started or stopped, so that the startability and fuel efficiency can be improved.

Further, since the vehicle is in the MD mode when the vehicle starts, quick acceleration can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a turbo-compound engine according to an embodiment of the present invention.
1 is a system diagram of the connection / disconnection clutch control system, FIG. 2 (a) is a graph showing the performance of the control system of FIG. 1, FIG. 3 is a system diagram of a modification of the control system, and FIG. It is a graph.

The turbo compound engine of this embodiment also has substantially the same configuration as the conventional turbo compound engine shown in FIG. 5, and has a control system shown in FIG. 1 as a control system for the first and second hydraulic clutches. The system is used.

In FIG. 1, reference numeral 12 denotes a hydraulic clutch corresponding to the first and second hydraulic clutches 12a and 12b in FIG. The pressurized hydraulic oil is configured to be supplied via the electromagnetic switching valve 2. Further, a controller 5 for operating the electromagnetic on-off valve 2 is provided, and the controller 5 is provided with an engine speed signal 6 measured by a tachometer 6.
a and a shift lever position signal 7a of the automatic transmission 7 are input.
In the (neutral) range or the P (parking) range, the electromagnetic on-off valve 2 is closed and the hydraulic clutch 12 is turned on.
When the engine is idling, the engine is set to the FT mode, and when the shift lever position is not in the N range or the P range and the engine speed is equal to or less than an arbitrarily set speed, the electromagnetic on-off valve 2 is opened and the hydraulic clutch is opened. Is turned on to set the engine to the MD mode.

The reference numeral 3 in FIG.
Indicates a pressure gauge.

As described above, in this embodiment, switching between the FT mode and the MD mode is performed according to the position of the shift lever of the automatic transmission 7, so that fuel consumption and noise during idling can be reduced, and the vehicle can be reduced. Transient responsiveness can be improved.

More specifically, in FIG. 2 (a), the driver first puts the shift lever in the N (neutral) range. At this time, since the oil flowing into the clutch is almost in the "LOW" state (line B), the clutch is also in the OFF state (lines C and D).

As a result, the exhaust turbocharger is not connected to the engine crankshaft, and the supercharging mode is in the FT (free turbo) mode. As a result, the idling fuel efficiency while the vehicle is stopped is improved.

Next, the driver puts the shift lever into the D (drive) range for the purpose of starting. At this time, the solenoid on-off valve is switched, and the oil flows into the hydraulic clutch and “H
IGH "state. As a result, the hydraulic clutch (generally, a friction plate type is adopted) is turned on with slippage. The rotation of the exhaust turbocharger is also increased in proportion to the state of the clutch, and the operation mode changes from the FT mode to the MD mode. In this state, start preparation is completed.

When the driver steps on the accelerator, the engine already in the MD mode can obtain a sufficient boost pressure and can accelerate quickly, and the time until the vehicle reaches an arbitrary vehicle speed (t) _a ) becomes shorter. When compared to the t _b in FIG. 2 (b), it is readily understood that a t _a> t _b.

In FIG. 2 (a), the horizontal axis indicates time, and the vertical axis indicates engine speed, exhaust turbocharger speed, clutch state and clutch oil pressure, respectively, and line A indicates engine speed. , Line B is the exhaust turbocharger rotation speed, line C
Indicates the clutch state, and line D indicates the clutch oil pressure.

Next, a modification shown in FIG. 3 is a case where a manual transmission is used as a transmission. In this case, a manual transmission is used instead of the shift lever position signal of the automatic transmission of the above-described embodiment. The difference is that the speed position signal 9a of the transmission of the transmission 9 is input to the controller 5. In this example, when the engine speed reaches an arbitrarily set speed, and when shifting (shift up) is performed. In this case, for example, when the vehicle shifts from the first gear to the second gear of the next gear at the start, the shift is detected and the MD mode at the start is switched to the FT mode.

As described above, in this example, the mode is switched from the MD mode to the FT mode at the time of upshifting. Therefore, as shown in FIG. 4, the vehicle speed E, the engine speed F, and the exhaust turbocharger speed G before and after shifting. Does not drop significantly (this point can be easily understood by comparing with E ', F', G 'of the conventional example), and therefore, the transient response of the vehicle can be improved. It is also possible to make the time t _a from when the vehicle starts to reach an arbitrary vehicle speed shorter than t _{b in the} conventional case.

[0034]

As described in detail above, the following effects and advantages can be obtained by the on-vehicle turbo compound engine of the present invention. (1) By switching between the FT mode and the MD mode according to the shift lever position of a vehicle equipped with a turbo compound engine, it is possible to reduce fuel consumption and noise during idling. (2) The transient response of the vehicle can be improved. (3) Since the demand for the responsiveness of the hydraulic clutch is reduced, the capacity of the hydraulic clutch and the hydraulic pump can be reduced, and the strength of the reduction gear train can be reduced, thereby contributing to downsizing of the engine. (4) By detecting the engine speed and the gear position of the transmission of the vehicle, turning on and off the connecting / disconnecting clutch and switching between MD mode and FT mode, the drop in turbocharger speed after shifting and the engine acceleration Can be prevented, and the transient response of the vehicle can be improved.

[Brief description of the drawings]

FIG. 1 is a system diagram of a connection / disconnection clutch control system for an on-vehicle turbo compound engine as one embodiment of the present invention.

2A is a graph showing the same performance, and FIG. 2B is a graph showing the performance of a conventional on-board turbo compound engine.

FIG. 3 is a system diagram of a modified example of the control system.

FIG. 4 is a graph showing the performance of the one of FIG.

FIG. 5 is a schematic view of a conventional turbo compound engine.

[Explanation of symbols]

 2 solenoid on-off valve 4 hydraulic pump 5 control valve 6 tachometer 6a speed signal 7 automatic transmission 7a shift lever position signal 9 manual transmission 9a gear position signal 12 hydraulic clutch

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ identification code FI F02D 45/00 310 F02D 45/00 310M (58) Fields investigated (Int.Cl. ⁶ , DB name) F02B 37/04

Claims (1)

(57) [Claims] 1. A turbo compound engine mounted on a vehicle, a reduction gear train comprising an exhaust turbocharger and two parallel gear trains for connecting the exhaust turbocharger to a crankshaft of the engine. One of the two parallel gear trains is configured as a gear train for driving the exhaust turbocharger from a crankshaft of the engine, and the other is an exhaust turbocharger. A hydraulic clutch that can be connected and disconnected with a one-way clutch that can transmit power in the driving direction and does not transmit power in the opposite direction, and is configured as a gear train that drives the crankshaft of the engine from the side. The mechanical drive mode, the turbo compound mode and the free turbo mode are controlled by the connection / disconnection control of each hydraulic clutch. The operation mode can be selectively performed, and the connection / disconnection control of each of the hydraulic clutches is controlled by a shift lever position signal or a gear position signal of the transmission of the vehicle, and the engine speed. An in-vehicle turbo compound engine, characterized in that it is performed on the basis of: