JPS626261Y2 - - Google Patents

Description

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

The effectiveness of the exhaust brake, that is, the friction horsepower, improves as the pressure of the exhaust manifold (hereinafter referred to as exhaust pressure) increases. Therefore, the higher the sealing degree of the exhaust shutter provided in the exhaust passage of the engine, the better. However, when the exhaust brake is activated during high-speed operation of the engine, the exhaust pressure rises above the seating force of the exhaust valve, inducing the exhaust valve to open abnormally, causing exhaust to flow back into the cylinder during the intake stroke and damage the intake system. The noise from Also, as mentioned above, if the exhaust valve opens abnormally (is pushed open by the exhaust gas in the exhaust manifold) and the exhaust flows back into the cylinder, carbon etc. discharged into the manifold will also flow back into the cylinder. This causes various problems.

The present invention has been made in view of the above, and an object of the present invention is to provide an exhaust brake device that can prevent abnormal opening of the exhaust valve and ensure sufficient frictional horsepower during low-speed operation. .

The present invention will be explained in detail below based on illustrated embodiments.

In FIG. 1, an exhaust shutter 3 is pivotally mounted by a support shaft 2 in a housing 1 interposed in the middle of an exhaust pipe of an engine (not shown). 4 is spindle 2
This is a bearing that is pivotally attached to the housing 1. An arm 5 is fastened and fixed to one end of the support shaft 2 with a nut 6, and the tip of the arm 5 is connected via a link 8 to the tip of a piston rod 7 of an exhaust brake cylinder (not shown). The housing 1 is provided with a bypass passage 9 that communicates between the upstream and downstream sides of the exhaust shutter 3, and a bypass valve 10 is provided at the upstream end of this passage 9. The bypass valve 10 is connected to the diaphragm 1 of the diaphragm actuator 11.
2 via a rod 13, and a pressure chamber 14 defined by the diaphragm 12 is provided with a spring 15 which holds the bypass valve 10 closed via the diaphragm 12 and the rod 13. Note that a chamber 16 defined from the pressure chamber 14 via the diaphragm 12 is open to the atmosphere. Then, the housing 1 installed in the middle of the engine's intake passage
An intake shutter 18 that opens and closes in synchronization with the exhaust shutter 3 is provided in the main passage 7, and the tip of a pipe 19 connected to the pressure chamber 14 is exposed to the auxiliary passage in the housing 17. .

In the exhaust brake device configured as described above, when a required signal is transmitted, the exhaust brake cylinder (not shown) is extended, and its piston rod 7, link 8, and arm 5 are moved in a predetermined direction to close the exhaust shutter 3. Rotate. Therefore, the exhaust pressure in the exhaust manifold increases and friction horsepower is generated in the engine. Further, since the intake shutter 18 is also rotated to close in synchronization with the closing operation of the exhaust shutter 3, the main passage within the housing 17 is closed.

When the intake shutter 18 is rotated to close in this manner, negative pressure is generated within the intake manifold. In addition, the suction negative pressure generated in this way is
There is no need to explain in detail that the higher the rotational speed of the engine, the stronger the force becomes.

Here, the diaphragm actuator 11
The pressure chamber 14 and the inside of the intake manifold are communicated through the pipe 19 and the auxiliary passage in the housing 17, so that the suction load caused by the blockage of the intake shutter 18 is not introduced into the pressure chamber 14. Ru. When the tensile force of the diaphragm 12 due to the negative pressure introduced into the pressure chamber 14 in this way becomes larger than the pressing force of the spring 15, that is,
When the rotational speed of the engine reaches a predetermined value or higher and the exhaust pressure in the exhaust manifold becomes greater than the seating force of the exhaust valve, the diaphragm 12 moves toward the pressure chamber 14 against the spring 15. Then,
Bypass valve 10 is pulled in the same direction via rod 13, so that bypass passage 9 is opened.

Furthermore, the opening area of the bypass passage 9, that is, the opening degree of the bypass valve 10, increases as the engine rotational speed increases and the suction negative pressure becomes stronger.
The upstream exhaust pressure can be maintained at a substantially constant value slightly smaller than the seating force of the exhaust valve. Therefore, the abnormal opening of the exhaust valve that tends to occur during high-speed operation can be prevented without sacrificing the frictional horsepower during low-speed operation.

Figure 2 shows the characteristics of suction negative pressure and friction horsepower with respect to engine speed when the exhaust brake is activated.In the past, as the engine speed decreased, as shown by the solid line, By installing _the exhaust pressure adjustment mechanism as mentioned above, the frictional horsepower, which had been decreasing almost in proportion to be.

In the embodiment shown in FIGS. 3 and 4, instead of providing a bypass passage, the rotating shaft core of the exhaust shutter 3 is formed hollow, and a leak passage 20 is provided perpendicular to this hollow part. Then, a rod 13 is attached to the diaphragm actuator similar to the above.
By fitting the piston valve 21 connected through the hollow part into the hollow part, the leak passage 20 is kept fully closed until the rotational speed of the engine reaches a predetermined value or more. For example, as the rotational speed increases, the opening area of the leak passage 20 by the piston valve 21 is gradually increased to increase the amount of exhaust gas leaking when the exhaust brake is activated.

In the embodiment shown in FIG. 5, a leak hole 22 is formed in the exhaust shutter 3, and a valve plate 23 covering the leak hole 22 is pivotally attached to the upstream side surface of the exhaust shutter 3 with a pin 24. Then, the tip of the rod 13 connected to the diaphragm actuator similar to the above is plunged into engagement with the elongated hole 25 of the valve plate 23 at the rotational shaft core of the exhaust shutter 3, thereby causing the engine to rotate in the same manner as described above. The opening degree of the leak hole 22 can be changed depending on the speed.

As explained above, according to the present invention, the degree of sealing of the exhaust shutter is changed according to the suction negative pressure that responds to the rotational speed of the engine. Abnormal valve opening can be prevented. In addition, since the suction negative pressure that detects the rotational speed of the engine can be directly used as the power source for operating the exhaust pressure adjustment mechanism, it can be implemented using only a mechanical configuration without using a rotational speed sensor or its control circuit. , it is also advantageous in terms of cost.

[Brief explanation of the drawing]

The figures show an exhaust brake device according to the present invention, and FIG. 1 is a cross-sectional view of the main parts of the first embodiment;
Fig. 2 is a friction horsepower characteristic diagram same as above, Fig. 3 is a sectional view of the main part of the second embodiment, Fig. 4 is a - sectional view of Fig. 3, and Fig. 5 is a sectional view of the main part of the third embodiment. It is a diagram. 3...Exhaust shutter, 9...Bypass passage, 10...Bypass valve, 11...Diaphragm actuator, 18...Intake shutter, 20...Leak passage, 21...Piston valve, 22...Leak Hole, 23...valve plate.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) An exhaust shutter that blocks the exhaust passage of the engine when a predetermined signal is transmitted, an intake shutter that also blocks the intake passage of the engine, and an intake shutter that blocks the engine's intake negative pressure. an exhaust pressure adjusting mechanism that is operated by a diaphragm actuator as a power source and reduces the degree of sealing of the exhaust shutter in accordance with an increase in suction negative pressure when the suction negative pressure exceeds a predetermined value; Brake device. (2) The exhaust pressure adjustment mechanism is comprised of a bypass passage that communicates the upstream and downstream sides of the exhaust shutter, and a bypass valve that widens and narrows this passage. The exhaust brake device according to item 1. (3) Utility model registration claim 1, characterized in that the exhaust pressure adjustment mechanism is comprised of a leak hole provided in the exhaust shutter and a valve body that widens and narrows the leak hole. Exhaust brake device described in.