JPS63306230A - Exhaust controller for vehicle - Google Patents

Abstract

PURPOSE:To change a torque characteristic according to driving conditions by selecting one of plural opening control characteristics of the exhaust control valve installed in an exhaust pipe. CONSTITUTION:Plural opening control characteristics, to engine speed, of the exhaust control valve 20 installed exhaust pipe 16 are stored in a memory device 64. One of these opening control characteristics is selected by a selector device 62 according to each signal out of an engine speed detecting device 56 and a vehicle travel speed detecting device 70. Using the selected opening control characteristic, the exhaust control valve 20 is controlled to the desired opening by a central processing unit 66. With this constitution, a torque characteristic can be changed according to driving conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an exhaust control device for a vehicle, which includes an exhaust control valve provided at the downstream opening end of an exhaust pipe extending from an engine exhaust port to an expansion chamber. .

(Background of the Invention) It is known that in 4-stroke engines, 2-stroke engines, etc., exhaust gas is intermittently guided into the exhaust pipe by opening and closing the exhaust valve, causing an inertial effect and a pulsation effect of the exhaust gas in the exhaust pipe. . These effects (referred to as dynamic effects) vary depending on engine speed. Therefore, if this dynamic effect is maximized to increase the volumetric efficiency at the rotational speed, the dynamic effect acts in the opposite direction at other rotational speeds, resulting in a significant decrease in the volumetric efficiency. Therefore, if the exhaust system specifications (exhaust pipe length, exhaust pipe diameter, etc.) are set so that this dynamic effect is optimal in the high speed range, the torque will significantly decrease (toilet valley) in the medium speed range. There was a problem that occurred.

Therefore, an exhaust control valve is installed near the opening end of the exhaust pipe to the expansion chamber to change the exhaust flow path surface (1), reducing the flow path area in the rotational speed range where the volumetric efficiency is low, and reducing the flowpath area in the other rotational speed ranges. It has been considered to create smooth torque characteristics without torque valleys by increasing the road area.

However, depending on the running conditions of the small wheels, it may be preferable to have a torque valley. For example, when accelerating, if there is this torque valley, the acceleration feeling from the middle of acceleration will be intense, improving the driving feeling.

(Object of the Invention) The present invention has been made in view of the above circumstances, and an eleventh object thereof is to provide a vehicle exhaust gas control device that can change the torque characteristics to the desired torque characteristics depending on the driving conditions. .

(Structure of the Invention) According to the present invention, this object includes an exhaust pipe whose one end is connected to an exhaust port of an engine and whose other end opens into an expansion chamber, and an exhaust control valve that changes the exhaust flow area of the exhaust pipe. A vehicle comprising: an engine rotational speed detection means; an opening detection means for the exhaust control valve; a storage means for storing a plurality of opening control characteristics of the exhaust control valve with respect to the engine rotational speed; characteristic selection means for selecting one; target opening detection means for determining a target opening of the exhaust control valve with respect to engine speed using the selected opening control characteristic; This is achieved by a vehicle exhaust gas control device characterized by comprising a drive means for controlling a valve.

(Example) Fig. 1 is an overall system diagram of an embodiment of the present invention, Fig. 2 is a plan cross-sectional view of the exhaust control valve, Fig. 3 is a cross-sectional view taken along line mm,
FIG. 4 is a functional block diagram, and FIG. 5 is an operational characteristic diagram.

In FIG. 1, the symbol lO is a 4-cycle 4 for motorcycles.
It is a cylinder engine. This engine 10 has a crankcase 12 and a cylinder 14 extending into an obliquely upwardly curved blade.

The exhaust system runs from the front of the cylinder 14 to the crankcase 12.
The exhaust pipe 16 is provided with four exhaust pipes 16 extending downward, and an exhaust control valve 20 connected to the rear end of the exhaust pipe 16 to collect the exhaust gas from each exhaust pipe 16 and guide it to a muffler 18.

The podium 22 of the exhaust control valve 20 has four parts as shown in FIG.
A branch pipe section 24 (24a to 24d) that is connected to each exhaust pipe 16 of the book and forms an exhaust pipe together with the exhaust pipe 16, and one expansion chamber 26 in which the downstream opening end of this branch pipe section 24 opens;
The main collecting pipe portion 28 is integrally cast from cast stainless steel. The branch pipe portion 24 has each branch end on the first stream side formed into a circular cross section and connected to each exhaust pipe 16 . Further, the downstream opening end of the branch pipe portion 24 has a vertically long rectangular opening shape, and the IIM IWW2B5 are opened in parallel.

30 is a crank-shaped valve body (Fig. 2), and this valve body 3
0 is rotatably supported at both ends on the left and right walls of the expansion chamber 26,
The intermediate portion 32 has an arcuate cross section. Circular openings are formed in the left and right walls of the expansion chamber 26, and these openings are closed by bearing plates 34, 36. The shafts at both ends of the valve body 30 are respectively supported by bearing plates 34 and 36, and one shaft portion 30a passes through the bearing plate 34 and projects outward, and a pulley 38 is fixed to this projecting end. The intermediate portion 32 faces the downstream opening of the branch portion 24, that is, the downstream opening end of the exhaust pipe 16. As shown in FIG. 3, the outer peripheral surface of the intermediate portion 32 and the downstream opening end of the exhaust pipe 16 are formed in an arc shape centered on the rotation center of the valve body 30, and are close to each other. The pulley 38 is rotated by a motor 42 via a wire 40. Note that the opening degree of the valve body 30 is 0, which is detected by a potentiometer 43 provided on the motor 42, and this potentiometer 43 forms the opening degree detection means A of the exhaust control valve 20.

The intake system includes a surge tank 46 connected to the intake pipe 44, an intake air purifier 48 on the upstream side thereof, a throttle j↑50, and a fuel injection valve 52. 54 is an ignition plug, which is ignited by an ignition circuit 56 at a predetermined crank angle. In this embodiment, the engine rotation speed N is detected from this ignition circuit 56, and this ignition circuit 56 is connected to the engine rotation speed detection means B.
form.

In Figure 1, 58 is the gear shift pedal, and 60 is the crankcase 12.
The drum 60 is a speed change drum of a transmission housed in the transmission, and this drum 60 is rotated by the pedal 58 to change speed. The rotational position of the gear change drum 60, that is, the gear position n, is detected by a gear position detection switch 62. In this embodiment, characteristic selection means C for selecting one of the opening degree control characteristics described later is formed by this switch 62.

Reference numeral 64 denotes a ROM as a storage means, in which a plurality of opening control characteristics of the exhaust control valve 20 with respect to the engine rotational speed N are stored, for example, the three types shown in FIG.
, ■ are stored.

66 is a CPU, which, as shown in FIG.
A characteristic reading means E for reading out either I or III (FIG. 5B), a target opening detecting means F for determining the target opening e for the engine speed N based on the read characteristics, and a target opening detecting means F for determining the target opening e for the engine rotation speed N based on the read characteristics Compare e and current opening degree θ and calculate the difference (e−θ
). Here, the characteristic reading means E reads the opening characteristic I when the gear position n is at a low speed such as the 1.2nd speed, the opening characteristic II when the gear position n is at a middle speed such as the 3rd and 4th speed, and the When in high speed gear such as 5th gear, select opening characteristic ■. Further, 68 is a driver, and this driver 68 and the motor 42 constitute a driving means H. The obtained difference (θ−θ) is sent to this driver 68,
The motor 42 is controlled to match [1 calibration degree e].

Next, the operation of this embodiment will be explained. If the gear is currently in the low gear, the CPU 66 selects the opening characteristic and reads out the target opening θ for the engine rotational speed N at that time. At this time, the exhaust control valve 20 is closed during idling (opening ratio 10 to 3).
(approximately 0%), and above that it is fully open (100% aperture ratio). Therefore, at this time, the exhaust control valve 20 only has the function of stabilizing idling, and the torque characteristic T shown in FIG.
As shown in (I), there is a torque valley in the medium speed range. For this reason, torque increases rapidly from the latter half of the medium speed range,
It is possible to obtain driving characteristics with an emphasized sense of acceleration.

If the gear is in the middle speed, the CPU 66 selects the opening characteristic II, reads out the target opening θ according to the rotational speed N at that time, and opens the exhaust control valve 20 half-open in the low-medium speed range and fully open in the high-speed range. control. At this time, the torque in the medium speed range increases, the torque valley disappears, and smooth torque characteristics can be obtained. The reason is as follows.

In other words, the positive pressure wave caused by the opening of the exhaust valve of the engine IO propagates in the exhaust pipe 16 at the speed of sound, and the negative pressure wave generated by the rapid expansion at the open end propagates in the opposite direction through the exhaust pipe 16 at the speed of sound. and return to the exhaust valve of the engine 10.

If the exhaust control valve 20 located near this opening end is closed, the positive pressure wave caused by the opening of the exhaust valve will be transmitted to the exhaust control valve 20.
0 and returns to the exhaust valve at the speed of sound as a positive pressure wave. Therefore, if the exhaust control valve 20 is controlled to reduce the exhaust flow path area to 1/2, a negative pressure wave generated by the open end of the exhaust pipe and returned, and a positive pressure wave reflected by the exhaust control valve 20. The sum with the wave is zero. At this time, the pulsation effect is canceled out, and a decrease in volumetric efficiency (occurrence of torque valley) in the medium speed range can be suppressed. Therefore, it is suitable for running in a middle speed gear where driving is relatively calm.

Furthermore, when the gear position n becomes a high speed position, the CPU 66 selects the opening degree characteristic (3), and the exhaust control valve 20 is fully opened in the low and high speed ranges of the engine, and half open in the middle speed range. Therefore, at this time, the effects of exhaust interference between the cylinders in the low speed range are canceled out, the output in the low and high speed ranges is increased, and easy driving is possible without frequent gear changes in the high speed range.

In this embodiment, the characteristic selection means C is constituted by a switch 62 for detecting the gear position n of the transmission. However, in place of this switch 62, a vehicle speed detection means 70 (see FIG. 4) is provided to detect the engine speed N and vehicle running speed. It is also possible to detect the speed V, calculate the gear position n from these, and select the opening characteristic corresponding to the gear position n.

FIG. 6 shows another embodiment of the characteristic selection means C, in which a manually operable selection switch 7 is provided on an instrument panel 72 of a motorcycle.
4 so that the desired opening characteristic can be determined manually. That is, when driving in a sports-oriented manner, for example, select the characteristic ■ in Figure 5B to improve the sense of acceleration, and when driving quietly and with low fuel consumption, select m.
All you have to do is select the characteristics of In FIG. 6, 76 is a steering handlebar, and 78 is a fuel tank.

(Effects of the Invention) As described above, the present invention stores a plurality of opening characteristics of the exhaust control valve, and controls the opening and closing of the exhaust control valve according to the opening characteristics selected from among them. The engine's torque characteristics can be changed depending on the driving conditions and the driver's preferences, allowing for a variety of driving possibilities.

[Brief explanation of the drawing]

Fig. 1 is an overall system diagram of an embodiment of the present invention, Fig. 2 is a plan sectional view of the exhaust control valve, Fig. 3 is a sectional view taken along the line m-■, Fig. 4 is a functional block diagram, and Fig. 4 is a functional block diagram. Figure 5 is an operating characteristic diagram, and Figure 6
The figure shows another embodiment of the characteristic selection means. DESCRIPTION OF SYMBOLS 10... Engine, 16... Exhaust pipe, 20... Exhaust control valve, 26... Expansion chamber, 62... Gear stage detection switch, 74... Selection switch.

Claims (4)

[Claims] (1) In a vehicle equipped with an exhaust pipe having one end connected to an exhaust port of the engine and the other end opening into an expansion chamber, and an exhaust control valve that changes an exhaust flow path area of the exhaust pipe, an engine rotation speed detection means; an opening detection means for the exhaust control valve; a storage means for storing a plurality of opening control characteristics of the exhaust control valve with respect to an engine rotational speed; a characteristic selection means for selecting one of the opening control characteristics; and a drive means for controlling the exhaust control valve to this target opening degree. Characteristic vehicle exhaust control device. (2) The exhaust gas control device for a vehicle according to claim 1, wherein the characteristic selection means includes a gear position detection switch that detects a gear position of a transmission of the engine. (3) The characteristic selection means determines the opening control characteristic to be selected based on the gear position determined from the engine speed and the vehicle running speed. Control device. (4) The exhaust gas control device for a vehicle according to claim 1, wherein the characteristic selection means is comprised of a manually operable selection switch.