JP4155695B2 - Exhaust brake device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust brake device for an internal combustion engine, and more particularly to a technique for preventing an increase in engine rotation speed even when an electrical short circuit occurs in an operation control system of the exhaust brake device.
[0002]
[Prior art]
In general, an exhaust brake device is attached to a commercial vehicle such as a truck equipped with a diesel engine in order to improve deceleration performance. The exhaust brake device is positioned as an auxiliary brake device that applies a large braking force to the vehicle by closing the exhaust passage and operating the internal combustion engine as a compressor by an exhaust shutter interposed in the exhaust passage.
[0003]
The exhaust brake device is attached not only to a diesel engine but also to a compressed natural gas (hereinafter referred to as “CNG”) engine. In a CNG engine, an air-fuel mixture is formed by mixing fuel and air with a mixer, so backfire may occur when the exhaust brake device is operated. For this reason, in order to prevent the formation of air-fuel mixture, as disclosed in Japanese Utility Model Laid-Open No. 6-40326, a bypass passage for bypassing the mixer and the throttle valve is provided, and an electromagnetic on-off valve is interposed in the bypass passage Has been proposed.
[0004]
Here, in the conventional CNG engine, the exhaust brake device is controlled by an operation control system as shown in FIG. That is, when it is detected by the clutch switch 1 that the clutch is in the engaged state, an operation instruction is issued by the exhaust brake operation switch 2, and an operation command is issued from the control unit 3, the I / O of the control unit 3 The transistors 3a and 3b, which are terminals, operate, and the bypass passage is opened by the electromagnetic on-off valve 4. At the same time, the coil portion 5a of the exhaust brake relay 5 is turned ON and the terminal portion 5b is short-circuited, whereby the exhaust shutter is rotated by the exhaust shutter valve 6 and the exhaust passage is closed.
[0005]
[Problems to be solved by the invention]
However, in such an operating system, for example, if an electrical short circuit occurs in the transistor 3a as the I / O terminal, the on-off valve 4 is turned on even if the exhaust brake operating command is not issued, and the bypass is bypassed. The passage is opened. In this case, in the mass flow type internal combustion engine in which the fuel supply amount is calculated from the intake flow rate Q and the engine rotational speed Ne, the fuel supply amount is increased by the increase of the intake flow rate Q, and the engine rotational speed Ne is increased. . If the engine rotational speed Ne increases, the braking force of the entire vehicle may decrease when the vehicle is braked.
[0006]
Therefore, in view of the conventional problems as described above, the present invention provides an engine that can be used even when an electrical short circuit occurs in the operation control system of the exhaust brake device when the exhaust brake device is attached to the mass flow internal combustion engine. An object of the present invention is to provide an exhaust brake device for an internal combustion engine in which the rotational speed is prevented from increasing.
[0007]
[Means for Solving the Problems]
For this reason, in the first aspect of the present invention, as shown in FIG. 1, a bypass passage C that bypasses the throttle valve B interposed in the intake passage A, a passage opening / closing mechanism D that opens and closes the bypass passage C, An exhaust shutter G that closes the exhaust passage E and acts as an internal combustion engine F as a compressor to generate a braking force, a shutter opening / closing mechanism H that opens and closes the exhaust shutter G, and an operating condition of the exhaust brake based on the engine operating state An operation condition determining means I for determining whether or not the condition is satisfied, and a physically separate electric part that performs a switch operation when the operation condition determining means I determines that the exhaust brake operation condition is satisfied. and I / O pin actuating means L for the two I / O terminals J and K respectively operated, and the exhaust brake relay M normally-open type having a terminal portion for short-circuiting operation by the coil unit and which, It comprise configured, wherein the driving circuit of the coil portion of the exhaust brake relay M, while the one of the I / O terminal J is interposed, to an output circuit of the terminal portion of the exhaust brake relay M, the shutter The opening / closing mechanism H, the other I / O terminal K connected in series and the passage opening / closing mechanism D are interposed in parallel .
[0008]
According to such a configuration, when the exhaust brake operating condition is satisfied, the two I / O terminals composed of physically separate electric parts that perform the switching operation are operated . When one I / O terminal is activated, the coil portion of the exhaust brake relay is activated and the terminal portion is short-circuited. The shutter opening / closing mechanism connected thereto is activated and the exhaust passage is blocked by the exhaust shutter. . Further, when the other I / O terminal is operated simultaneously, the passage opening / closing mechanism is operated and the bypass passage is opened.
[0009]
Here, for example, consider a case where one I / O terminal is short- circuited due to an electrical short circuit. Then, when the exhaust brake is not operated, the exhaust passage is closed and a braking force is generated, but the other I / O terminal is not operated, so the bypass passage is not opened. On the other hand, consider the case where the other I / O terminal is short- circuited due to an electrical short circuit. Then, when the exhaust brake is not operated, the other I / O terminal is always operated, but one I / O terminal is not operated , the exhaust passage is not blocked , and the bypass passage is not opened.
[0010]
For this reason, even if a failure occurs in the operation control system due to an electrical short circuit, the intake flow rate does not increase due to the opening of the bypass passage. Therefore, even in the mass flow type internal combustion engine, the fuel supply amount is prevented from increasing as the intake air flow rate increases, and the engine rotational speed is prevented from increasing.
[0011]
According to a second aspect of the present invention, the operating condition determining means is configured to determine whether or not an exhaust brake operating condition is satisfied when the clutch interposed in the power transmission system is in an engaged state. Features.
[0012]
According to such a configuration, only when the clutch interposed in the power transmission system is in the engaged state, the operating condition determining means determines whether the operating condition of the exhaust brake is satisfied based on the engine operating condition. Therefore, the exhaust brake operates only when the clutch is in the engaged state. For example, the exhaust brake does not operate when the transmission is shifted, and unnecessary operation of the exhaust brake is prevented.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 2 shows an overall configuration in which an exhaust brake device according to the present invention is applied to a mass flow internal combustion engine.
[0014]
A fuel injection valve 14 for injecting fuel to each cylinder is attached to the intake manifold 12 of the internal combustion engine 10, and an intake passage 16 that guides air in which impurities are filtered by an air cleaner (not shown) is connected. An air flow meter 18 that detects the intake air flow rate Q and a throttle valve 20 whose opening degree changes in conjunction with an accelerator pedal (not shown) are interposed in the intake passage 16. Further, the intake passage 16 is provided with a bypass passage 22 so as to bypass the throttle valve 20, and an electromagnetic on-off valve 24 (passage opening / closing mechanism) for opening and closing the bypass passage 22 is interposed therein.
[0015]
On the other hand, an exhaust passage 28 that guides exhaust gas is connected to the exhaust manifold 26 of the internal combustion engine 10. The exhaust passage 28 includes an exhaust shutter 30 that constitutes a part of the exhaust brake device, an air-fuel ratio sensor 32 that detects an air-fuel ratio, a catalyst 34 that purifies exhaust, and a muffler 36 that reduces exhaust noise. Be dressed. The exhaust shutter 30 is connected to the operating rod 40a of the air cylinder 40 via a link mechanism 38, and is connected to the air reservoir 46 by a pipe 44 in which an electromagnetic exhaust shutter valve 42 is interposed. Therefore, the air cylinder 40 is operated by controlling the opening and closing of the exhaust shutter valve 42, and the operation and release control of the exhaust brake device is performed.
[0016]
A shutter opening / closing mechanism is configured including the link mechanism 38, the air cylinder 40, and the exhaust shutter valve 42.
In addition to the air flow meter 18 and the air-fuel ratio sensor 32, an exhaust brake operation switch 48, a clutch pedal switch 50, and a rotation speed sensor 52 are provided in order to control the operation of the exhaust brake device. The exhaust brake operation switch 48 is a switch for instructing whether or not to operate the exhaust brake device, and is attached, for example, near a combination switch of a steering column (not shown). The clutch pedal switch 50 is a switch for detecting a connection / disconnection state of a clutch (not shown) interposed in the power transmission system, and is provided along with the clutch pedal 54. The rotation speed sensor 52 is a switch that detects the engine rotation speed Ne, and is attached to a signal disk plate (not shown), for example.
[0017]
Output signals of the air flow meter 18, the air-fuel ratio sensor 32, the exhaust brake operation switch 48, the clutch pedal switch 50, and the rotation speed sensor 52 are input to a control unit 56 incorporating a microcomputer, respectively. Then, the control unit 56 controls the driving of the on-off valve 24 and the exhaust shutter valve 42 in order to control the exhaust brake device according to a flowchart described later.
[0018]
The control unit 56 realizes the operating condition determining means and the I / O terminal operating means by software.
FIG. 3 is an electric circuit diagram of an operation control system of the exhaust brake device having such a configuration.
[0019]
The + terminal of the power supply 58 whose ground is grounded is connected to the transistor 56a which is the I / O terminal of the control unit 56 via the clutch pedal switch 50, the exhaust brake operation switch 48 and the coil portion 60a of the exhaust brake relay 60. The The positive terminal of the power source 58 is connected to one end of the terminal part 60 b of the exhaust brake relay 60, and the other end part of the terminal part 60 b is an I / O terminal of the control unit 56 via the electromagnetic on-off valve 24. In addition to being connected to the transistor 56b, it is connected to the electromagnetic exhaust shutter valve 42. Here, the transistors 56a and 56b, which are I / O terminals of the control unit 56, are physically separate elements that operate simultaneously when an operation command for the exhaust brake device is generated.
[0020]
Next , the control content of the exhaust brake device will be described using the flowchart shown in FIG.
[0021]
In step 1 (abbreviated as “S1” in the figure, the same applies hereinafter), the engine speed Ne is detected by the rotation speed sensor 52.
In step 2, the air-fuel ratio is detected by the air-fuel ratio sensor 32.
[0022]
In step 3, it is determined based on the detected engine speed Ne and air-fuel ratio whether or not the exhaust brake operating condition is satisfied. Here, in order to satisfy the operating condition, it is necessary that the engine rotational speed Ne is equal to or higher than a predetermined speed and the air-fuel ratio is equal to or higher than a predetermined value. This is to prevent stall and backfire. If the exhaust brake operating condition is satisfied, the process proceeds to step 4 (Yes), and if the exhaust brake operating condition is not satisfied, the process returns to step 1 (No).
[0023]
In addition, the process of step 1-step 3 corresponds to an operation condition determination means.
In step 4, the transistor 56 a serving as the I / O terminal of the control unit 56 is operated to turn on the exhaust brake relay 60. As a result, the terminal portion 60 b of the exhaust brake relay 60 is short-circuited, air is supplied from the air reservoir 46 to the air cylinder 40 by the electromagnetic exhaust shutter valve 42, and the exhaust passage 28 is closed by the exhaust shutter 30. A large braking force is generated in the vehicle by causing the internal combustion engine 10 to act as a compressor. The process for operating the transistor 56a of the control unit 56 corresponds to the I / O terminal operating means .
[0024]
In step 5, the transistor 56 b serving as the I / O terminal of the control unit 56 is operated to operate the electromagnetic on-off valve 24. As a result, the bypass passage 22 is opened, and intake air is introduced into the internal combustion engine 10 via the bypass passage 22. Therefore, the resistance of the internal combustion engine 10 as a compressor is increased, and the braking force by the exhaust brake device is efficiently produced in combination with the blockage of the exhaust passage 28 by the exhaust shutter 30. The process for operating the transistor 56b of the control unit 56 corresponds to the I / O terminal operating means .
[0025]
According to the exhaust brake device described above, the exhaust passage 28 is blocked by the exhaust shutter 30 when an electrical short circuit occurs in the operation control system of the exhaust brake device, for example, the transistor 56a which is the I / O terminal of the control unit 56. However, as long as the exhaust brake operating condition is satisfied and the transistor 56b does not operate, the bypass passage 22 is not opened. Further, when an electrical short circuit occurs in the transistor 56b as the I / O terminal of the control unit 56, the bypass passage 22 is not opened unless the exhaust brake operating condition is established and the transistor 56a is operated.
[0026]
For this reason, in a mass flow internal combustion engine equipped with an exhaust brake device, even if an electrical short circuit occurs in the operation control system of the exhaust brake device, the intake flow rate Q does not increase unless the operating conditions are satisfied, and the fuel supply The engine speed Ne can be prevented from increasing due to the increase in the amount. Therefore, even during braking by the exhaust brake device, a reduction in braking force due to an increase in the engine rotational speed Ne is prevented, and safety can be improved.
[0027]
In the configuration described above, the transistor 56a, which is the I / O terminal of the control unit 56, is taken as an example of the electric element that operates the exhaust brake relay 60. However, for example, a short circuit of a relay, a photocoupler, or the like may occur. It may be an electrical component that is compatible.
[0028]
【The invention's effect】
As described above, according to the first aspect of the present invention, even if a failure occurs in the operation control system due to an electrical short circuit, the intake flow rate is prevented from increasing due to the opening of the bypass passage. Even in the mass flow type internal combustion engine, it is possible to prevent the fuel supply amount from increasing with an increase in the intake flow rate, and to prevent the engine speed from increasing.
[0029]
According to the second aspect of the present invention, unnecessary operation of the exhaust brake is prevented, and the running feeling can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram corresponding to claims according to claim 1. FIG. 2 is an overall configuration diagram of an internal combustion engine to which an exhaust brake device according to the present invention is applied. FIG. 3 is an electric circuit diagram showing the operating system. FIG. 5 is an electric circuit diagram showing an operating system of an exhaust brake device in the prior art.
DESCRIPTION OF SYMBOLS 10 Internal combustion engine 16 Intake passage 20 Throttle valve 22 Bypass passage 24 On-off valve 28 Exhaust passage 30 Exhaust shutter 38 Link mechanism 40 Air cylinder 42 Exhaust shutter valve 50 Clutch pedal switch 56 Control unit 60 Exhaust brake relay

Claims (2)

A bypass passage that bypasses the throttle valve interposed in the intake passage; and
A passage opening and closing mechanism for opening and closing the bypass passage;
An exhaust shutter that closes the exhaust passage and causes the internal combustion engine to act as a compressor to generate a braking force;
A shutter opening and closing mechanism for opening and closing the exhaust shutter;
An operating condition determining means for determining whether an operating condition of the exhaust brake is satisfied based on the engine operating state;
I / O terminal actuating means for actuating two I / O terminals consisting of physically separate electric parts that perform a switch operation when it is judged by the actuating condition judging means that the exhaust brake operating condition is satisfied. When,
A normally open exhaust brake relay having a coil portion and a terminal portion that is short-circuited thereby ;
It is configured to include a,
The drive circuit of the coil part of the exhaust brake relay is provided with the one I / O terminal, while the output circuit of the terminal part of the exhaust brake relay is connected in series with the shutter opening / closing mechanism. An exhaust brake device for an internal combustion engine, wherein the other I / O terminal and the passage opening / closing mechanism are interposed in parallel .   2. An exhaust brake for an internal combustion engine according to claim 1, wherein said operating condition determining means is configured to determine whether or not an exhaust brake operating condition is satisfied when a clutch interposed in a power transmission system is in an engaged state. apparatus.

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