JPH0231529Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is an engine braking device that absorbs the kinetic energy of the vehicle through the pumping loss of the engine and obtains braking force. This invention relates to a device equipped with a gas conduction means that conducts gas to a combustion chamber during an intake stroke and increases braking force.

Conventionally, exhaust brakes have been used to close the engine exhaust passage with an on-off valve to increase exhaust pressure, have the engine perform a pump operation, and obtain a braking force in response to this operation, or to adjust the engine stroke phase to near the top dead center of the compression stroke. It was known to open a certain combustion chamber and release the stored energy as pressure to brake the engine. However, as the output of engines increases, a device with higher braking ability is desired, and for example, an engine braking device 1 as shown in FIG. 1 has been proposed. This engine braking device 1 has 4 cylinders 4
It is attached to engine 2 of the cycle. An on-off valve 4 capable of preventing exhaust gas from being discharged into the atmosphere is attached to the exhaust pipe 3 of the engine 2, and this on-off valve 4 is operated by an air cylinder 7 supplied with compressed air from an air tank 5 through an air passage 6. do. The air passage 6 is opened and closed by a solenoid valve 10, which is a normally closed valve that opens when both the manual switch 8 and the accelerator pedal interlocking switch 9 are turned on. Therefore, when both switches 8 and 9 are turned on, the on-off valve 4 closes the exhaust pipe 3 and operates as an exhaust brake. On the other hand, each combustion chamber 11 of the engine 2 communicates with an intake port 17 opened and closed by an intake valve 12, an exhaust port 14 opened and closed by an exhaust valve 13, and an exhaust pipe 3, as shown in FIG. 3rd valve 1
A third port 16 that is opened and closed at 5 is provided.
The intake and exhaust valves 12 and 13 are opened and closed by intake and exhaust cams 25 and 26 on a camshaft 24 via rocker arms 18 and 19, push rods 20 and 21, and tappets 22 and 23, respectively. Third valve 15
is a normally closed valve to which an initial load is applied by a spring 27, and a piston 28 is formed at the upper end of the valve.
This piston is a cylinder portion 30 within the bearing member 29.
It is inserted into. The cylinder portion 30 communicates with an oil reservoir 31, as shown in FIG. The oil reservoir 31 communicates with the inside of a cylinder member 34 attached to the crankcase, and also communicates with the oil supply path 3 through a normally closed valve 32.
It is connected to 3. Low pressure oil is supplied to this oil supply path 33 from an oil pump (not shown) of the engine 2. The normally open valve 32 can be closed by a solenoid 35, and is closed when both the manual switch 8 and the accelerator-linked switch 9 are turned on, thereby sealing the oil reservoir 31 side. A piston 37 that is pressed against the exhaust cam 26 by a spring 36 is fitted into the cylinder member 34 . By the way, when this piston 37 moves to the farthest right (in FIG. 3) due to the lift of the exhaust cam 26, that is, when the oil sump 31 side is pressurized and the third valve 15 can be opened, this exhaust gas is removed. The stroke phase of the combustion chamber 11 facing the cam 26 is set to be near the top dead center of the compression stroke.

In this engine brake device 1, when the accelerator interlock switch 9 and the manual switch 8 are turned on, the on-off valve 4 is closed and the normally open valve 32 is closed. Then, the exhaust pipe 3 on the upstream side of the on-off valve 4 becomes clogged with exhaust gas, causing an increase in pumping loss in the engine 2.
Moreover, in the combustion chamber 11 whose stroke phase is near the top dead center of the compression stroke, the third valve 15 is operated to open, and the third valve 15 is opened.
Compressed gas is ejected through the port 16, and the compression work is absorbed, and this high-pressure gas generates pressure waves in the exhaust pipe 3 on the upstream side of the on-off valve 4, a part of which is generated near the bottom dead center of the intake stroke. The gas flows into another combustion chamber (not shown) located in the third valve 15 by pushing open the exhaust valve of that combustion chamber, increasing the filling amount of gas in the same chamber and increasing the compression work in the same chamber. It is possible to absorb this and generate a sufficiently high braking force.

By the way, as shown in Fig. 3, cylinder 3
0, the oil reservoir 31 and the inside of the cylinder member 34 are sealed by closing the normally open valve 32, and the third valve 15 is operated. However, when the third valve 15 is not operated, the low pressure oil supplied to these
The oil flows in from the oil sump 3 side, and part of it flows out from the oil drain path 38 through a check valve (not shown).
Low oil pressure is always applied to the 1 side. For this reason, the exhaust cam 26 and the piston 37 are subjected to pressing force against each other, and the generation of these surface pressures has the disadvantage of accelerating the wear of both.

SUMMARY OF THE INVENTION An object of the present invention is to provide an engine brake device that can shut off oil supply to a pressurizing piston that constitutes a hydraulic pressure generating means for operating a normally closed valve when the engine is not in operation.

The engine braking device according to the present invention includes an exhaust passage that communicates with a combustion chamber when an exhaust valve is opened, and an on-off valve that is installed in the exhaust passage and opens and closes the exhaust passage, and operates an exhaust braking force when the exhaust passage is blocked. , a solenoid valve that is interposed in an air passage communicating between an air cylinder that drives the on-off valve and the air tank and opens and closes the air passage; one end communicates with the exhaust passage between the on-off valve and the exhaust valve; A port whose end is communicated with the combustion chamber, and a port that is disposed in the port on the side of the combustion chamber, opens and closes the combustion chamber, and operates a brake force when the combustion chamber is opened near the top dead center of the compression stroke. a gas passage means having a piston connected to the normally closed valve and a cylinder portion into which the piston is inserted; a pressurizing piston that responds by contacting the exhaust cam; and a pressurizing piston into which the pressurizing piston is inserted. Hydraulic pressure is generated to supply high pressure oil to the cylinder section so that the normally closed valve opens near the top dead center of the compression stroke, which has a pressure cylinder and a pressurization chamber defined by the pressure cylinder and the pressure piston. means, a hydraulic oil supply passage having one end communicating with the pressurizing chamber and the other end communicating with the cylinder portion; one end communicating with the pressurizing chamber and the other end communicating with an oil supply source supplying low pressure oil; an oil drain passage whose one end communicates with the oil supply passage and discharges pressurized oil in the pressurizing chamber; and an oil drainage passage that is interposed in a communicating portion of the oil supply passage and the oil drainage passage and communicates the oil supply source with the pressurization chamber. an electromagnetic three-way valve that can selectively switch between shutting off the oil supply source and the pressurizing chamber and communicating the pressurizing chamber and the oil drain path, when operating the engine brake; , closes the on-off valve and opens the normally closed valve near the top dead center of the compression stroke, and when the engine brake is not operated, the solenoid valve and the solenoid valve open the on-off valve and stop opening of the normally closed valve. A gas discharge control means for switching and controlling the electromagnetic three-way valve; a safety valve disposed in the hydraulic oil supply passage for discharging the high-pressure oil at a predetermined pressure; , the supply of low-pressure oil from the oil supply source to the pressurizing chamber is cut off, and the pressurized oil in the pressurizing chamber is discharged from the oil drain path, so that the pressurizing piston is rendered inoperable.

The present invention will be described below with reference to the accompanying drawings. Incidentally, an engine braking device 50 as an embodiment of the present invention has a general overall structure similar to that shown in FIG. 1, and has a similar general structure of a combustion chamber 11 as shown in FIG. Hereinafter, the same constituent members as these will be denoted by the same reference numerals, and their repeated explanation will be omitted.
An engine braking device 50 shown in FIG. 4 includes a gas discharge control means 51 that switches and controls an on-off valve 4 (see FIG. 1) and an electromagnetic three-way valve (hereinafter simply referred to as a three-way valve) 63 attached to the exhaust pipe 3 of the engine 2.
and gas conduction means 52. The gas communication means 52 is formed by a third port 16 attached to each combustion chamber 11, a third valve 15 that opens and closes the third port 16, and its drive system. The cylinder head 53 in the upper part of the combustion chamber 11 is formed with a third port 16 and intake and exhaust ports 17 and 14 (see FIG. 2).
A bearing member 54 is integrally attached to the upper part. Note that the third port 16 communicates with the exhaust port 14 side in a merged manner. This third port 16 can be opened by the third valve 15 as a normally closed valve. The third valve 15 is biased in the closing direction by a spring 27, and has a piston 28 attached to its upper portion. The piston 28 is fitted into a cylinder portion 55 formed within the bearing member 54 and is operated by high pressure oil. In addition, the reference numeral 56 indicates a relief valve as a safety valve, which prevents the oil pressure of the cylinder portion 55 from excessively (usually leaking at about 150 kg/cm ² ).
Preventing it from getting bigger.

A hydraulic pressure generating means 69 for driving the third valve 15 of the gas conduit 52 is a pressurizing cylinder 59 connected to the cylinder portion 55 via a connecting pipe 58 forming a hydraulic oil supply path.
and a pressurizing piston 60 fitted therein. An exhaust cam 26 is in contact with a tappet portion 62 that is integrally connected to the pressurizing piston 60. The pressurizing chamber 591 of the pressurizing cylinder 59 is connected to an oil supply path 61 that supplies low-pressure oil from a sub-oil gear gallery 64 as an oil supply source. The oil supply path 61 is connected to a sub-oil gear gallery 64 and an oil drain path 65 that go to an unillustrated oil jet of the engine 2 via a three-way valve 63.
It is possible to alternatively communicate with. The three-way valve 63 is a solenoid valve, which allows the control piston 63 to
Slide 1. That is, when the manual switch 8 and the accelerator-linked switch 9 are turned on, the three-way valve 63
is turned on, allowing the oil supply passage 61 that was communicating with the oil drain passage 65 (shown by a solid line in FIG. 4) to communicate with the sub-oil gear gallery 64 (see FIG. 5).
In addition, in FIG. 4, reference numeral 66 indicates a check valve, which prevents oil from flowing back toward the sub-oil gear gallery 64 when the pressurizing piston 60 of the pressurizing cylinder 59 is pressurized. Preventing. The tappet portion 62 is biased toward the exhaust cam 26 by a spring 67. When this tappet portion 62 moves to the leftmost position (in FIG. 4) due to the lifting height of the exhaust cam 26,
When pressurizing the engine, the stroke phase of the combustion chamber 11 facing the exhaust cam 26 is set to be near the top dead center of the compression stroke.

The operation of the engine braking device 50 shown in FIG. 4 will be explained. When the driver returns the accelerator (not shown) and turns on the accelerator interlocking switch 9 and the manual switch 8, the on-off valve 4 closes and the three-way valve 63 is turned on.
makes the sub-oil gear gallery 64 communicate with the oil supply path 61, and closes the oil drain path 65. As a result, the on-off valve 4
The exhaust pipe 3 on the upstream side is clogged, and the engine 2 generates a braking force due to increased pumping loss. Moreover, the third valve 15 facing the combustion chamber 11 whose stroke phase is near the top dead center of the compression stroke is pressurized by the oil in the pressurizing cylinder 59 facing it, and the high pressure oil presses the piston 28 and presses the third valve 15. The valve 15 is opened and compressed gas is injected into the third port 16 to absorb the compression work of the combustion chamber 11 and obtain braking force. At the same time, the high-pressure gas discharged into the exhaust pipe 3 on the upstream side of the on-off valve 4 becomes a pressure wave and is transmitted, and a part of it is transmitted to another combustion chamber (not shown) near the bottom dead center of the intake stroke. Push open the exhaust valve of the chamber and let it flow in. For this reason,
The amount of gas charged in the combustion chamber increases, and the compression work in the same chamber also increases.If this gas is similarly ejected from the third valve, the compression work can be absorbed more effectively, and the braking force is increased accordingly. It can be generated sufficiently high.

In the engine braking device 50 shown in FIG. 4, a pressurizing chamber 591 in its hydraulic pressure generating means is selectively connected to a sub-oil gear gallery 64 as a hydraulic pressure source and an oil drain path 65 via a three-way valve 63. . For this reason,
A third valve that connects the pressurizing cylinder 59 to the oil drain path 65.
When the valve 15 is not in operation, the pressurizing cylinder 59 is isolated from the sub-oil gear gallery 64 side, and the exhaust cam 26 and the tappet portion 62 are brought into contact with each other only by surface pressure due to the weak elastic force of the spring 67. , it is not affected by the oil pressure on the pressurizing cylinder 59 side, and it is possible to prevent both wear and output loss. Furthermore, there is an advantage that a drop in the oil pressure of the sub-oil gear gallery 64 can be prevented. Note that when the pressurizing cylinder 59 and the sub-oil gear gallery 64 can communicate with each other, that is, when the third valve 15 can open, the engine brake is being applied, and in this state, the combustion chamber is almost completely closed. There is no combustion inside the sub-oil gear 64, and both the heat load and the heat internal pressure are low, so changes in the oil pressure inside the sub-oil gear gallery 64 do not cause any problems.

The three-way valve 63 of the engine brake device 50 shown in FIG. 4 was designed to slide the control piston 631, but instead, as shown in FIG. 6, the rotary valve 68 is rotated 90 degrees by a solenoid (not shown). It is also possible to adopt a configuration in which the oil passages are switched, and other well-known means can be used in the same way.

[Brief explanation of the drawing]

Fig. 1 is a schematic overall view of an engine braking device equipped with a third valve, Fig. 2 is a sectional view of the main part of the part shown in Fig. 1, and Fig. 3 is a sectional view of the main part of the gas conduction means of a conventional engine braking device. FIG. 4 is a sectional view of a main part of an engine braking device as an embodiment of the present invention,
FIG. 5 is a cross-sectional view of the three-way valve in FIG. 4 when it is in operation, and FIG. 6 is a cross-sectional view of essential parts of the three-way valve used in an engine braking device as another embodiment of the present invention. 3...Exhaust pipe, 4...Opening/closing valve, 11...Combustion chamber, 15...Third valve, 16...Third port, 26
...Exhaust cam, 50...Engine brake device,
51... Gas discharge control device, 52... Gas conduction means, 59... Pressurizing cylinder, 60... Pressurizing piston, 61... Oil supply path, 63, 68... Three-way valve, 6
4...Sub oil gear gallery, 65...Oil drain path, 6
6...Check valve, 69...Hydraulic pressure generating means, 591...
...pressurized chamber.

Claims (1)

[Scope of utility model registration request] An exhaust passage that communicates with the combustion chamber when the exhaust valve is opened, an on-off valve installed in the exhaust passage that opens and closes the exhaust passage and activates the exhaust brake force when the exhaust passage is blocked, and air that drives the on-off valve. A solenoid valve is installed in an air passage communicating between the cylinder and the air tank and opens and closes the air passage, one end of which communicates with the exhaust passage between the on-off valve and the exhaust valve, and the other end of which communicates with the combustion chamber. a normally closed valve disposed in the port on the side of the combustion chamber that opens and closes the combustion chamber and applies a braking force when the combustion chamber is opened near the top dead center of the compression stroke; A gas communication means having a connected piston and a cylinder portion into which the piston is inserted, a pressurizing piston that responds by contacting an exhaust cam, a pressurizing cylinder into which the pressurizing piston is inserted, and the above-mentioned pressurizing cylinder. a pressurizing chamber defined by a pressurizing piston, and a hydraulic pressure generating means for supplying high pressure oil to the cylinder section so that the normally closed valve opens near the top dead center of the compression stroke, one end of which is connected to the pressurizing chamber; A hydraulic oil supply passage that communicates with the cylinder portion at its other end, an oil supply passage whose one end communicates with the pressurizing chamber and whose other end communicates with an oil supply source that supplies low-pressure oil, and one end which communicates with the oil supply passage. and is interposed in a communication portion between the oil supply path and the oil drainage path for discharging the pressure oil in the pressurizing chamber, and communicates the oil supply source with the pressurizing chamber, or the oil supply source and the When operating an electromagnetic three-way valve that can selectively switch between blocking the pressurizing chamber and communicating the pressurizing chamber and the oil drain path, and an engine brake,
The on-off valve is closed and the normally-closed valve is opened near the top dead center of the compression stroke, and when the engine brake is not activated, the solenoid valve and the above-mentioned solenoid valve are opened and the normally-closed valve is stopped from opening. A gas discharge control means for switching and controlling the electromagnetic three-way valve, a safety valve disposed in the hydraulic oil supply passage and discharging the high-pressure oil at a predetermined pressure, and the electromagnetic three-way valve further comprises:
When the engine brake is not operated, the supply of low-pressure oil from the oil supply source to the pressurizing chamber is cut off, and the pressurized oil in the pressurizing chamber is discharged from the oil drain passage, and the pressurizing piston is deactivated. An engine braking device characterized by: