JPH0819865B2 - Exhaust brake device for engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine exhaust blower configured to open and close an engine exhaust pipe with a slide valve.
Regarding equipment.

[0002]

2. Description of the Related Art An exhaust brake device for forcibly increasing the pressure in an exhaust pipe to brake an engine under load has conventionally been constructed such that a slide valve provided in the exhaust pipe is opened and closed by a pneumatic cylinder. Are known. However, in this type of exhaust brake device, the high exhaust pressure generated during exhaust braking acts on the cylinder rod sliding part of the pneumatic cylinder as it is, so high temperature exhaust gas enters the cylinder from the gap of this sliding part. There was a problem of getting in. In other words, the exhaust gas is not only hot but also
It contains components such as bon which adversely affect the slidability, which causes the slidability of the piston rod to deteriorate over time.

Therefore, in recent years, as shown in FIG. 3, a shaft b of a slide valve a and a piston rod d of a pneumatic cylinder c are used.
Are integrated shafts, and a bearing f is provided on the exhaust pipe e side of the pneumatic cylinder c from the pneumatic cylinder c side to the exhaust pipe e side.
A bearing housing h is formed so as to accommodate a bearing and a seal bearing g, and a high pressure seal gas pressure is supplied to a ring-shaped space i sandwiched by the bearings f and g. ("Slide type exhaust brake device" (Japanese Utility Model Laid-Open No. 58-12646)).

[0004]

With the configuration as proposed, it becomes possible to prevent the exhaust gas from entering from the bearing side due to the pressure of the high-pressure seal gas. By the way, even in the proposal, in order to protect bearings and seal bearings from unburned exhaust such as carbon, the frequency of use of exhaust brake and high-temperature exhaust gas environment remain unchanged. It is desirable that the seal gas is positively leaked into both the exhaust pipe and the cylinder, and the carbon that is trying to adhere to the bearing and the seal bearing is positively blown away. In the structure in which high-pressure air of the same pressure is simultaneously applied to the front and rear surfaces of the piston, the pressure on the working side of the piston loses the spring force and the force to defeat the pressure in the spring chamber and slides. The valve cannot be activated. Therefore, the applicant of the present invention weakens the set force of the spring and introduces high-pressure air into the gas seal immediately after the piston rod d has completely moved, and supplies the compressed air to the air chamber of the cylinder. Is used as a separate system to supply working air at a pressure higher than that of the spring chamber side, and the receiving area (volume) is increased by increasing the cylinder inner diameter to cause a pressure difference,
I examined such a method. However, the spring force cannot be made so weak in that the return speed of the piston rod d is kept constant, and increasing the air pressure of the compressed air is not suitable for the capacity and safety of the air tank, and the cylinder diameter is increased. Was not suitable in terms of space and weight, and neither of them could be adopted. It is possible to increase the size of the air vent hole in the spring chamber more than necessary in order to positively discharge the compressed air from the cylinder, but this is to allow the air pressure of the air tank to be consumed unnecessarily. There is a high possibility that the operation of the system will be uncertain, and it cannot be adopted.

As described above, in order to enable the maintenance and the accurate operation of the cylinder of the exhaust brake device by using the high-pressure seal air, the piston of the pneumatic cylinder during the exhaust brake is operated. It is necessary to fully consider back pressure.

An object of the present invention is to provide an exhaust brake device of the above-mentioned type, in which the supply / discharge timing of the seal gas is delayed by a predetermined time with respect to the supply of working air to the piston rod, The precise operation of the cylinder and the sealing of the cylinder by the sealing gas are possible.

[0007]

In order to achieve the above-mentioned object, the present invention is a spring retarder which is attached to an exhaust pipe and has a slide valve for opening and closing the exhaust pipe at the tip of its piston rod. Type pneumatic cylinder, an operating air supply / exhaust system connected to the operating air chamber of the spring return type pneumatic cylinder to open / close the exhaust pipe by supplying / discharging operating air by switching the first three-way valve, and A gas seal part is formed on the cylinder wall of the exhaust pipe to exert a seal gas pressure on the sliding surface of the piston rod, and a second three-way valve connected to this gas seal part is used to change the seal. A seal gas supply / exhaust system for supplying / discharging high-pressure gas, and switching the second three-way valve to the seal gas supply position with a delay of a predetermined time immediately after switching the first three-way valve to the exhaust brake operating position, and the above 1 a three-way valve exhaust blur - the second three-way valve with a delay of a predetermined time immediately after switching to the key released position sheet -
And a valve switching means for switching to the gas exhaust position.

[0008]

When there is an instruction to operate the exhaust brake, the valve switching means immediately switches the first three-way valve to the exhaust brake position and supplies the working air to the working air chamber of the spring-return type pneumatic cylinder. Then, the piston rod is moved to move the slide valve to the closed position of the exhaust pipe. Immediately after the slide valve is moved to the position where the exhaust pipe is closed, the second three-way valve is closed.
Switch to the rugas supply position. In other words, until the piston rod is completely moved to the position where the exhaust pipe is closed, the supply of seal gas is cut off to eliminate the back pressure that hinders the movement of the piston rod. For the first time, seal gas is supplied to the gas seal section to prevent exhaust gas from entering the cylinder.

On the other hand, when there is an instruction to release the exhaust brake, the valve switching means switches the first three-way valve to the exhaust brake releasing position to discharge the working air from the working air supply / discharge system, and thereafter. When the internal pressure of the exhaust pipe upstream of the slide valve drops to the normal pressure, the second three-way valve is switched to the seal gas discharge position. Therefore, the supply of the seal gas to the gas seal portion is continued even during the release of the exhaust brake of the slide valve, and the pressure of the seal gas prevents the exhaust gas from entering the cylinder.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the exhaust brake device of the present invention basically comprises a spring-return type pneumatic cylinder 1 and a tip of a piston rod 2 of the spring-return type pneumatic cylinder 1. A slide valve 4 which is integrally mounted to open and close the exhaust pipe 3, and the spring return type pneumatic cylinder 1 and the exhaust pipe 3 are connected to each other and protruded to the outside of the spring return type pneumatic cylinder. The piston rod 2 and the slide valve 4 are constituted by a housing member 5 formed in a tubular shape so as to be reciprocally housed in the opening / closing direction.

Specifically, in the cylinder 6, a spring 7 on the side of the exhaust pipe 3 and a working air chamber 9 on the opposite side are formed by a piston 7 of a piston rod 2 which is reciprocally accommodated therein.
And a return spring 10 for urging an elastic force in the spring chamber 8 in a direction to reduce the volume of the working air chamber 9 with respect to the piston 7. . A first air supply pipe 12 is connected to the rear end side of the cylinder 6 so as to communicate with the inside of the working air chamber 9 and supply the high pressure air from the air tank 11 to the working air chamber 9. The first air supply pipe 12 is configured to have a first electromagnetic three-way switching valve 13 with an atmosphere opening port in the middle thereof. When the first electromagnetic three-way switching valve 13 is switched to the atmosphere opening port, the pressure in the working air chamber 9 is released to the atmosphere to move the piston rod 2 to the maximum retracted position, that is, the slide valve 4 to the exhaust pipe 3. Is moved to the fully open position, and the high pressure air is introduced into the working air chamber 9 when the air opening port position is switched to the switching position where the first air supply pipe 12 and the working air chamber 9 are communicated with each other. Is allowed to move to the maximum forward position, that is, to the exhaust pipe 3 side, and the exhaust pipe 3 is closed.

The cylinder 6 is also provided with an exhaust pipe side partition wall, that is, a cylinder member 14, at the tip thereof so as to be airtightly fitted into the cylinder 6 by an inlay. The cylinder member 14 is formed by extending the inner peripheral portion of the spring chamber 8 side along the axial direction thereof into a columnar shape toward the working air chamber 9 side, and the outer peripheral side of the column upper portion is a return spring. A retainer portion 15 for seating 10 is formed, and a hole penetrating in the axial direction is opened in the shaft core portion, and the hole is used as a bearing hole 16 for accommodating the piston rod 2 reciprocally. The bearing hole 16 is provided in the working air chamber 9
Side and the exhaust pipe 3 side are expanded in a ring shape, and the working air chamber 9
The expanded portion on the side of the exhaust pipe 3 serves as a chamber 17, and the expanded portion on the side of the exhaust pipe 3 serves as a housing 19 for fitting the sleeve-shaped gas seal members 18, 18 at an axial interval. ing. Specifically, the gas seal member 18 has a hole 20 through which the piston rod 2 is reciprocally fitted to the axis thereof.
Further, the ring-shaped space formed between the gas seal members 18, 18 serves as a gas seal portion 21. On the other hand, in the cylinder member 14, a seal gas supply is provided to the flange portion 22 of the cylinder member 14, the other end of which is opened from the outer peripheral surface thereof and passes through the inside of the flange portion 22 in the radial direction to face the gas seal portion 21. It has a passage 23, and when pressurized air is supplied to the gas passage 23, the pressure of the high pressure air is applied to the outer peripheral surface of the piston rod 2. A second air supply pipe 24 is connected to the seal gas supply passage 23 for supplying and discharging high pressure air for sealing. In the embodiment of the present invention, the second air supply pipe 24 is the first
It is formed by branching from the upstream of the electromagnetic three-way switching valve 13, and in the middle thereof, a second electromagnetic three-way switching valve 25 with an atmosphere opening port is provided.

The slide valve 4 engages with the inner surface of the exhaust pipe 3 to open and close the exhaust pipe 3, and the front end of the slide valve 4 is engageable with the valve engaging groove 26 on the inner peripheral surface of the exhaust pipe 3. It is formed in a shape. The housing member 5 is formed integrally with flanges 28 and 29 that are joined to the cylinder member 14 and the mounting flange 27 of the exhaust pipe 3 at both ends thereof, and the axial center portion of the housing member 5 with respect to the inside of the exhaust pipe 3 is formed. Is formed with an engagement hole 30 for accommodating the slide valve 4 so that it can be moved back and forth.

The main object of the present invention is to provide an exhaust brake device of the type described above with a seal for the working air chamber 9.
The purpose is to delay the supply and discharge of rugas to enable the operation of the piston rod 2.

Therefore, according to the present invention, the first electromagnetic three-way switching valve 13 and the second three-way switching valve 25 are controlled to be opened and closed with a predetermined time difference t1 as shown in the timing chart of FIG. Is configured.

That is, in terms of electric circuit, the exhaust blower in the driver's seat
The switch 31 and the first electromagnetic three-way switching valve 13 are directly connected, the second electromagnetic three-way switching valve 25 is connected via the timer 32, and these first electromagnetic three-way switching valves 13 and 25 are connected.
As shown in the timing chart of FIG. 2, when the exhaust brake switch 31 is turned on, the first electromagnetic three-way switching valve 31 is turned on first (switching position for supplying high-pressure air) and the timer 32 is switched. ON of the first electromagnetic three-way switching valve
The second electromagnetic three-way switching valve 25 is turned on after a predetermined time t1 from
The relay circuit is configured so as to be (switching position for supplying seal gas), and the OF of the exhaust brake switch 31 is
At the same time as F, the relay circuit is configured such that the first electromagnetic three-way switching valve 31 is turned off first, and the timer 32 turns off the second electromagnetic three-way switching valve 25 after a predetermined time t1 from the turning off of the first electromagnetic three-way switching valve. are doing.

The predetermined time t1 is basically the working air chamber 8
The introduction of air (gas) having the same pressure into both the gas seal portion 21 and the gas seal portion 21 is completely eliminated so that the piston rod 2 operates normally, and the exhaust pipe 3 during the exhaust brake is also provided. Taking into account the rise in the internal pressure of the cylinder and the rise in the pressure in the exhaust pipe due to the fuel injected into the cylinder immediately before the release of the exhaust brake, the exhaust gas is prevented from entering the cylinder 6 at that time. .

That is, at the time of exhaust brake, the second electromagnetic three-way valve 25 is turned on before the exhaust pipe internal pressure reaches the exhaust pipe internal pressure for the engine by turning on the first electromagnetic three-way valve 13. As a result, the exhaust gas is prevented from entering the cylinder 6, and when the exhaust brake is released,
After releasing the exhaust brake, the second electromagnetic three-way valve 25 is kept ON until the exhaust pipe internal pressure becomes lower than the exhaust pipe internal pressure that allows the exhaust gas to enter the cylinder 6, and the exhaust gas into the cylinder 6 is exhausted. It tries to prevent the invasion of gas.

Next, the operation will be described.

When the exhaust brake actuation switch 31 is turned on, the first electromagnetic three-way switching valve 13 is actuated and the actuation air chamber 9
When the piston rod 2 is moved to the closing side of the exhaust pipe 3 and the slide valve 4 engages with the engaging portion 26 of the exhaust pipe 3, the upstream internal pressure of the exhaust pipe 3 increases and the internal pressure of the exhaust pipe 3 increases. Ascending causes the engine to undergo forced load braking.
Here, the second electromagnetic three-way valve 25 does not turn on until the exhaust pipe 3 internal pressure rises after the first electromagnetic three-way switching valve 13 turns on, but it turns on after a predetermined time t1 set by the timer 33. Therefore, high-pressure air (gas) is not simultaneously introduced into both the working air chamber 9 and the gas port 21, and the piston rod 2 operates normally. When the second electromagnetic three-way valve 25 is turned on, the gas seal portion 21 is connected to the second air supply pipe 24 and the seal gas supply passage 2 from the air tank 11.
High-pressure air is supplied through 3, and the pressure of the high-pressure air acting on the outer peripheral surface of the piston rod 2 prevents the exhaust gas from entering the cylinder 6. The second electromagnetic three-way switching valve 25 also serves to cut off the supply of the seal gas and at the same time discharge the exhaust gas through the gas seal portion 21.

When the exhaust brake is released, the first solenoid valve 13 is turned off at the same time when the exhaust brake operating switch 31 is turned off.
Then, the second electromagnetic three-way valve 25 is delayed by a predetermined time t1.
Turns off. Until the second electromagnetic three-way valve 25 is turned off, the exhaust pipe internal pressure changes from the accelerator depression to the slide valve 4
2 rises due to the fuel injected into the cylinder during the time t1 until the return is cut off (part A in FIG. 2), but the second electromagnetic three-way valve 25 has a certain amount of pressure in part A from the OFF of the first electromagnetic three-way valve 13. Since the ON state is maintained until the predetermined time t1 until the temperature falls, the invasion of the exhaust gas into the cylinder 6 is blocked even at this time.

As described above, according to the present invention, in consideration of the internal pressure of the exhaust pipe at the time of the exhaust brake and immediately after the release of the exhaust brake, the piston rod 2 is normally operated while preventing the exhaust gas from entering the cylinder 6. It is possible to protect the cylinder 6 from the exhaust gas by operating it in the above-mentioned manner, and its reliability and durability are greatly improved.

The device for producing the time lag with respect to the first solenoid valve 13 and the second solenoid valve 25 may be either electrical or mechanical, but a control unit interlocking with a timer or an electronic governor is actually used. Target.

[0025]

As is clear from the above description, the present invention exhibits the following excellent effects.

(1) Since the supply timing of the seal gas is shifted by a predetermined time with respect to the supply of the working air to the piston rod, the piston rod can be reliably operated and the cylinder can be sealed.

[Brief description of drawings]

FIG. 1 is a system diagram showing an exhaust brake device for an engine according to the present invention.

FIG. 2 is a timing chart showing the switching timing of the first electromagnetic three-way valve and the second electromagnetic three-way valve according to the present invention with respect to the exhaust pipe internal pressure.

FIG. 3 is a diagram showing a conventional example.

[Explanation of symbols]

 1 Spring Return Pneumatic Cylinder 2 Piston Rod 4 Slide Valve 9 Working Air Chamber 12 First Air Supply Pipe (Working Air Supply / Discharge System) 13 First Electromagnetic Three-way Switching Valve (First Three-way Valve) 24 Second Air Supply Pipe (Seal gas supply / discharge system) 21 Gas seal part 25 Second electromagnetic three-way switching valve (second three-way valve)

Claims (1)

[Claims] 1. A spring-return type pneumatic cylinder attached to an exhaust pipe and having a slide valve for opening and closing the exhaust pipe at a tip of its piston rod, and a working air chamber of the cylinder. An operating air supply / exhaust system for opening and closing the exhaust pipe by supplying and exhausting operating air by switching the first three-way valve, and a seal gas pressure acting on the piston rod sliding surface of the cylinder wall on the exhaust pipe side. The formed gas seal part, a seal gas supply / discharge system connected to the seal part for supplying / discharging high-pressure gas for sealing to / from the second three-way valve by switching the first three-way valve. Immediately after switching to the key operation position, the second three-way valve is switched to the seal gas supply position with a predetermined delay, and immediately after switching the first three-way valve to the exhaust brake release position, a predetermined time is delayed from the above. The second three-way valve And a valve switching means for switching to the exhaust position of the engine.
Ki device.