JPS581636Y2 - Exhaust brake device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an exhaust brake device used in dogs and medium-sized vehicles.

Large and medium-sized vehicles are equipped with exhaust brakes to increase the effect of so-called engine braking.

In a typical exhaust brake, when the exhaust brake switch, accelerator switch, and clutch switch are all turned on, the exhaust shutter is closed to close the exhaust passage and increase the pressure in the combustion chamber of the engine to perform braking.

In addition, due to such high exhaust pressure, the exhaust valve opens abnormally during the engine intake stroke, causing exhaust to flow back into the combustion chamber, which causes noise from the intake system, so an intake shutter is installed in the intake passage. The noise is suppressed by closing the intake shutter when the exhaust brake is operated.

However, when the intake passage is blocked by the intake shutter in this way, the filling efficiency of intake air is reduced, so it is undeniable that the braking effect of the exhaust brake associated with the action of the engine's compressor is reduced.

In a high engine speed range where the exhaust valve opening degree during the intake stroke increases due to an increase in exhaust pressure and the noise from the intake system increases accordingly, the intake shutter should be closed giving priority to the noise suppression measure. Although it is unavoidable, closing the intake shutter even if the button is pressed in a low engine speed range where the exhaust valve opening during the intake stroke is small and the intake system noise is not a problem will unnecessarily reduce the braking performance of the exhaust brake. It was an unreasonable structure.

The present invention was devised in view of these conventional drawbacks, and is designed to prevent the intake shutter from exhausting in the engine speed range above a predetermined value, where noise from the intake system due to abnormal opening of the exhaust valve during the intake stroke becomes a problem. The present invention provides an exhaust brake device in which the intake shutter is closed together with the intake shutter, but in an engine rotational speed range below this, the intake shutter is locked in the open position to improve braking performance.

The present invention will be described in detail below based on embodiments shown in the drawings.

Referring to FIG. 1 showing one embodiment, an exhaust shirt 2 disposed in an exhaust passage 1 is connected to an arm 3 and a rod 4 fixed to an end of a shaft protruding from the wall of the passage 1. Opening/closing is controlled by an air cylinder 5.

The air cylinder 5 is connected to a near reservoir 8 by a pipe 7 having an electromagnetic on-off valve 6 interposed therebetween.

An accelerator switch 10 is attached in conjunction with a control member 9a of a fuel injection pump 9 so that the signal line of the electromagnetic on-off valve 6 turns ON when an accelerator pedal (not shown) is released.
．． As in the conventional case, it is connected to a battery 15 via a clutch switch 12 that is turned on when the clutch pedal 11 is released and a brake switch 14 that is turned on when the exhaust brake 1/bar 13 is pulled.

On the other hand, an intake shutter 17 disposed in the intake passage 16 is controlled to open and close by an air cylinder 18 connected to the shutter 17 in the same manner as the exhaust shutter.
The air cylinder 18 is connected to a pipe 19 branching from the pipe I downstream of the electromagnetic on-off valve 6.

An electromagnetic on-off valve 20 constituting the present invention is installed in the pipe 19.

That is, the signal line of the electromagnetic on-off valve 20 is connected to the engine's tachometer 21.
It is connected to the battery 15 via an engine rotation speed detection switch 22 attached to the engine rotation speed, and when the engine rotation speed is below a predetermined value, the detection switch 22 turns OFF and the electromagnetic on-off valve 20 closes, and the engine rotation speed decreases. When the predetermined value is exceeded, the detection switch 22 is turned on, and the electromagnetic on-off valve 20 is energized and opened.

Alternatively, the detection switch 22 is turned ON to close the electromagnetic on-off valve 20 when the engine speed is below a predetermined value, and the detection switch 22 is turned OFF when the engine speed exceeds a predetermined value to open the electromagnetic on-off valve 20. You can.

The operation of the exhaust brake device having such a configuration will be explained.

In a high-speed region where the engine speed exceeds a predetermined value, the electromagnetic on-off valve 20 is open, so if the exhaust brake is operated in this state, the electromagnetic on-off valve 6 opens and compresses air from the near reservoir 8 to the air cylinder 5 through the piping 7. Air is supplied and the normally open exhaust shutter 2 is closed, and compressed air is also supplied to the air cylinder 18 through the piping 19, and the intake shutter 17 is also closed, eliminating noise from the intake system due to abnormal opening of the exhaust valve. The braking force characteristic shown in part A in FIG. 2 is obtained when this is prevented.

Furthermore, in a low speed region where the engine speed is below the predetermined value, the electromagnetic on-off valve 20 closes and the pipe I is cut off, so compressed air is supplied to the air cylinder 5 when the exhaust brake is operated, as in the case of a high speed region. is supplied and the exhaust shutter 2 is closed, but since the supply of compressed air to the air cylinder 18 is cut off, the intake shutter 17 is held in the open position, so the braking force characteristics are shown in part B of Fig. 2. As shown, the improvement is improved compared to the case where the intake shutter shown by the broken line is closed.

In addition, the braking characteristics showing the relationship between the time required after the start of exhaust brake operation and continuous speed are as shown by broken line C in Figure 3, and when the intake shutter is closed over the entire range of engine speed, as shown by the broken line. The vehicle speed decreases in a shorter time than before, and exhaust braking performance improves.

The opening/closing control of the electromagnetic on-off valve 20 is not limited to the one using the engine speed meter 21 shown in this embodiment, but may be performed by detecting the frequency generated by the alternator, for example.

The present invention can also be used in other types of systems, such as interlocking the intake shirt and exhaust shaft via flexible wires.The key point is to detect the engine rotational speed and detect the area where the speed exceeds a predetermined value. In this case, the configuration may be such that the four-inch comb is locked in the open position, and in a speed range below this, the lock is released to allow the intake shutter to close when the exhaust brake is operated.

As explained above, according to the present invention, when the exhaust plate material is made, the exhaust shutter is closed in the region where the engine rotational speed exceeds a predetermined value and the noise from the intake system is large due to the abnormal opening of the exhaust valve due to the rise in exhaust pressure. However, in the engine speed range below the predetermined value where noise from the intake system due to abnormal opening of the exhaust valve is low, the intake shirt is held in the open position and only the exhaust shutter is closed. Since the structure is configured to increase the braking force, there is a significant practical effect in that the braking performance of the exhaust brake can be greatly improved while fully satisfying the above-mentioned noise countermeasures.

[Brief explanation of drawings]

Fig. 1 is an overall system diagram of an exhaust brake device showing one embodiment of the present invention, Fig. 2 is a graph showing the relationship between the engine rotation speed and the braking force of the exhaust brake in the embodiment device, and Fig. 3 is a graph showing the relationship between vehicle speed and the time required after the start of exhaust brake operation, which is pressed on the device. 1...Exhaust passage, 2...Exhaust shutter, 1
6...Intake passage, 17...Intake shutter, 2
o: Solenoid on-off valve, 21: Engine speed meter, 22: Speed detection switch.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) An exhaust brake device configured to control the opening and closing of an exhaust shutter installed in an exhaust passage and an intake shutter installed in an intake passage in conjunction with each other. An exhaust brake device comprising a control means for locking an intake shutter in an open position in a speed range below a predetermined engine rotational speed and releasing the lock in a speed range exceeding the predetermined value. (■ The control means is an on-off valve that is installed in the air piping that supplies compressed air to the air cylinder for operating the intake shutter when the exhaust brake is operated, and whose opening and closing are controlled by detecting the engine rotation speed. Exhaust brake device according to scope item (1). (3) Claim for utility model registration, wherein the on-off valve is an electromagnetic on-off valve that is controlled to turn on and off by connecting to a speed detection switch attached to an engine speed meter. The exhaust brake device according to item (2).