JP2001082278A - Variable valve timing device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the opening/closing timing of an exhaust valve by changing the relative phase of a rotor to a housing, and to synchronize fuel injection timing with intake air timing by providing a driving means driving an injection pump on the housing. SOLUTION: In a diesel uniflow type engine of two cycle in-line three cylinders, exhaust gas is exhaust from four exhaust ports 92, and a exhaust valve 4 provided on each exhaust port 92 is driven to open/close by a exhaust cam 11 provided on a pair of exhaust cam shafts 1A, 1B. The first exhaust cam shaft 1A is chain-united to a crank shaft Cf through a variable valve timing device 5 changing the relative phase of a rotor with reference to a housing so as to control varying the opening/closing timing of the exhaust valve 4. In this case, in the housing, a driving pulley P1 is provided on the exhaust cam shaft 1A, and an injection pump 1P is driven by the rotation of the driving pulley P1 through a belt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve timing device for varying the opening / closing timing of an exhaust valve in a diesel internal combustion engine, and more particularly to driving an injection pump for fuel injection by utilizing rotation of an exhaust camshaft. About what you are doing.

[0002]

2. Description of the Related Art Generally, in a diesel engine, it is necessary to drive an injection pump for fuel injection in accordance with the opening and closing timing of an intake valve. The injection pump is connected so as to interlock with the camshaft. By the way, for example, in a uniflow type, each cylinder is provided with only an exhaust valve, and air is taken in from an intake hole provided in the cylinder inner wall by using a vertical movement of a piston to open the exhaust valve. I'm trying to exhaust. Therefore, an exhaust camshaft is used for driving the injection pump in such an engine.

[0003]

However, when such a type of engine is provided with a variable valve timing device as disclosed in Japanese Patent Application Laid-Open No. 11-132014, this device is attached to an exhaust camshaft. Since the opening / closing timing of the exhaust valve with respect to the intake timing is changed, there occurs a problem that the phase of the injection pump is shifted from the intake timing.

[0004]

SUMMARY OF THE INVENTION In view of the above-described problems, the present invention does not directly drive an injection pump by an exhaust camshaft, but uses a variable valve timing device that always rotates in synchronization with a crankshaft in a housing.
This is to drive an injection pump.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A variable valve timing apparatus for an internal combustion engine according to the present invention comprises a rotor fixed to an exhaust camshaft, a rotor rotatably connected to the rotor within a predetermined range, and a crank. A housing connected so as to rotate synchronously with the shaft, wherein the opening and closing timing of the exhaust valve can be variably controlled by changing the relative phase of the rotor with respect to the housing. And a driving means for driving the injection pump.

In such a case, in the uniflow type internal combustion engine, for example, in which only the opening and closing timing of the exhaust valve can be changed, the injection pump is driven by the housing which always rotates synchronously with the crankshaft. The fuel injection timing by the injection pump can be synchronized with the phase of the crankshaft, that is, the intake timing, without making major modifications to the device and its peripheral mechanism.

On the other hand, when the rotor is provided with an elastic body which constantly urges the housing in one direction, specifically, the advance direction, the elastic body is efficiently arranged, and particularly, the length in the axial direction is increased. To reduce the length, while fixing the drive pulley for driving the injection pump to the housing,
It is desirable to provide a housing space for housing the elastic body in the drive pulley.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The engine according to the present embodiment is a two-cycle in-line three-cylinder diesel uniflow type as shown in FIGS. When P reaches the vicinity of the bottom dead center, it inhales, and exhaust gas after explosion is discharged from four exhaust ports 92 provided at the upper end of each cylinder 9. These exhaust ports 92
Are respectively provided with exhaust valves 4. These exhaust valves 4 are opened and closed by exhaust cams 11 provided on a pair of exhaust camshafts 1A and 1B, respectively. The exhaust camshafts 1A and 1B are connected via a gear train 10 so as to rotate synchronously and in reverse with each other, and one exhaust camshaft 1A is chain-connected to a crankshaft Cf via a variable valve timing device 5. . At the center of the upper end of each cylinder 9, an injection nozzle (not shown) for fuel injection is provided. The injection nozzle is connected to the injection nozzle from an injection pump Ip via an injection pipe (not shown), an injection nozzle holder Ih, and the like. The fuel is pumped. The injection pump Ip is belt-driven by a driving pulley P1 attached to the variable timing device 5, as will be described later.

The variable valve timing device 5 utilizes a so-called swing cylinder mechanism, and comprises a rotor 2 fixed to an exhaust camshaft 1 and a housing 3 connected to the crankshaft Cf so as to always rotate synchronously. The opening and closing timing of the exhaust valve 4 can be variably controlled by changing the relative phase of the rotor 2 with respect to the housing 3. For example, the opening / closing timing of the exhaust valve 4 is moved to the advanced angle side during idling, and is moved to the retarded side when the load is high, thereby contributing to the improvement of the fuel efficiency and output of the engine or the drivability. I have.

The variable valve timing device 5 will be described in detail. As shown in FIGS. 3 and 4, the rotor 2 has a cylindrical shape and is fixed to one exhaust camshaft 1A at the outer end thereof. And three vanes 22 protruding radially from the outer periphery of the rotor main body 21 so as to be equidistant from each other. The housing 3 has a disk shape and has a holding space 31 provided therein for rotatably holding the rotor 2 within a predetermined range. The holding space 31 is provided with three chambers 32 each having a fan-shaped cross section for accommodating each vane 22 of the rotor 2, and each vane 22 divides each room 32 into the advance chamber 3.
2a and a retard chamber 32b. The timing sprocket SP1 fixed to the inner end of the housing 3 is connected to a drive sprocket SP2 provided on the crankshaft Cf via a timing chain CH so that the timing sprocket SP1 always rotates synchronously with the crankshaft Cf. Is configured.

[0011] The variable valve timing device 5 having such a configuration.
Is in one of the advance chamber 32a and the retard chamber 32b,
By moving the vane 22 by introducing or discharging pressure oil through an oil control valve, not shown, a switching control valve, the relative phase of the rotor 2 with respect to the housing 3, that is, the exhaust camshafts 1A and 1B with respect to the crankshaft Cf. The relative phase is arbitrarily changed to control the opening and closing timing of the exhaust valve.

In this embodiment, the spring case 8 is fastened to the outer end surface of the housing 3 by bolts, and the drive pulley P1 for driving the injection pump is fixed so as to fit over the spring case 8. are doing. The drive pulley P1 is connected to a driven pulley P2 fixed to a shaft of the injection pump Ip via a belt BT. The spring case 8 includes a cylindrical case main body 81 and a flange 82 provided integrally with the inner end of the case main body 81. The inner end face of the flange 82 is It is attached to the outer end face. The spring case 8 is provided with a spring receiving groove S having a ring-shaped cross section which is open at the inner end surface of the flange portion 82 and has a depth reaching substantially a half portion of the case body 81. The torsion spring 6, which is an elastic body, is housed therein. The torsion spring 6 has one end engaged with the spring case 8 and the other end engaged with the rotor 2 of the variable valve timing device 5, and constantly urges the housing 3 toward the advance side with respect to the rotor 2. This is because, for example, when the engine is stopped without the oil pressure being applied, the housing 3 is always moved to the advanced rotation end (the state shown in FIG. 4), and when the engine is started, the exhaust valve 4 is moved at the most advanced timing. It is designed to be reliably opened and closed.

According to this embodiment, the injection pump Ip is driven by the housing 3 which rotates synchronously with the crankshaft Cf, so that the fuel injection timing by the injection pump Ip is
It is possible to always synchronize the phase of the crankshaft Cf, that is, the intake timing. In addition, since the driving pulley P1 is disposed outside along the axial direction of the housing 3, the arrangement position of the conventional driving pulley is hardly required to be changed, so that it can be realized without major modification. Becomes

Further, a spring case 8 for accommodating the torsion spring 6 is disposed in the driving pulley P1.
Since the spring case 8 and the driving pulley P1 are partially overlapped with each other, the length in the axial direction can be particularly reduced, and the size can be reduced. In addition,
The present invention is not limited to the above embodiment, and various modifications are possible. For example, the invention is not limited to a uniflow type engine, and the present invention can be effectively applied to any engine having a configuration that can change only the exhaust valve timing. It goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0015]

According to the present invention described in detail above, the rotor fixed to the exhaust camshaft is rotatably connected to the rotor within a predetermined range and rotates synchronously with the crankshaft. In the variable timing device having a housing connected to the crankshaft, the injection pump is driven by the housing which always rotates synchronously with the crankshaft, so that the variable valve timing device and its peripheral mechanism are largely modified. In addition, the fuel injection timing by the injection pump can be synchronized with the phase of the crankshaft, that is, the intake timing.

On the other hand, when the rotor is provided with an elastic body which constantly urges the housing to rotate in one direction, specifically, the advance direction, the elastic body is efficiently disposed, and particularly, the length in the axial direction is increased. To reduce the length, while fixing the drive pulley for driving the injection pump to the housing,
It is desirable to provide a housing space for housing the elastic body in the drive pulley.

[Brief description of the drawings]

FIG. 1 is a schematic overall view showing an internal structure of an engine according to an embodiment of the present invention.

FIG. 2 is a partial sectional side view of the engine in the embodiment.

FIG. 3 is a side sectional view showing the variable valve timing device in the embodiment.

FIG. 4 is a front sectional view showing the rotor and the housing in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Exhaust camshaft 2 ... Rotor 3 ... Housing 4 ... Exhaust valve 5 ... Variable valve timing device 6 ... Elastic body (torsion spring) P1 ... Drive pulley (drive means) Ip ... Injection pump S ... Housing space

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ichiro Fujimura 2-1-1, Taoyuan, Ikeda-shi, Osaka Daihatsu Industry Co., Ltd. (72) Inventor Yoshio Kawaharaguchi 1-1-1, Showa-cho, Kariya, Aichi Prefecture Shares F term in company DENSO (reference) 3G016 AA03 AA08 AA12 BA06 BA23 BA28 CA25 CA27 CA29 CA59 DA01 GA01 3G092 AA02 AA03 AA06 AA11 DA02 DA09 DA14 DG02 DG05 FA50

Claims (2)

[Claims] A rotor fixed to an exhaust camshaft;
A housing rotatably connected to the rotor within a predetermined range and connected so as to rotate synchronously with the crankshaft, and by changing a relative phase of the rotor with respect to the housing, opening and closing timing of the exhaust valve. The variable valve timing device for an internal combustion engine is characterized in that the housing is provided with driving means for driving an injection pump for fuel injection. An elastic body for constantly urging the housing in one direction with respect to the rotor, wherein a driving pulley as driving means is fixed to the housing;
2. The variable valve timing device for an internal combustion engine according to claim 1, wherein a housing space for housing the elastic body is provided in the drive pulley.