KR100319120B1 - Engine auxiliary brake apparatus - Google Patents

Abstract

The present invention aims to provide an engine auxiliary brake device capable of maximizing a compression-pressing engine brake effect in an engine equipped with a supercharger using exhaust gas energy. An exhaust turbine 121 having a variable nozzle 151 whose flow rate is adjustable upstream thereof, and an intake compressor 122 that supercharges the intake air to the internal combustion engine 1 in association with the exhaust turbine 121; According to the driving state of the vehicle, the variable nozzle 151 is operated in a direction in which the passage cross-sectional area of the exhaust system decreases, and the cylinder 22 is selectively communicated near the compression stroke top dead center to open the compression pressure. For example, the port opening area of the exhaust valve 4 or the dedicated auxiliary exhaust valve 40 is set to 6.5% or more of the bore cross section of the cylinder 22, whereby the maximum absorption horsepower is achieved. That one will get a feature.

Description

Engine auxiliary brake device {ENGINE AUXILIARY BRAKE APPARATUS}

The present invention is an internal combustion engine having a turbocharger using exhaust gas, and a compression pressure opening means for communicating a cylinder of the internal combustion engine to an exhaust system to open the compression pressure in the cylinder to obtain high absorption horsepower (braking force). It relates to an engine auxiliary brake device having a.

In order to improve the output of the internal combustion engine, there is a technique of supercharging the intake air to the internal combustion engine by operating the supercharger installed in the intake machine using the exhaust gas from the internal combustion engine. Such a supercharging technique is called a turbocharger, and consists of an exhaust turbine installed in the exhaust system, and an intake compressor installed in the intake machine and connected to the exhaust turbine. In recent years, the flow rate (exhaust speed) of the exhaust gas introduced into the exhaust turbine is variably controlled in accordance with the operating state of the internal combustion engine by using a variable nozzle provided upstream of the exhaust turbine, thereby adjusting the supercharge amount. It is performed and is called VG (Variable Geometric) turbo.

On the other hand, when braking of a vehicle, there is a technique of communicating a cylinder of an internal combustion engine to its exhaust system to open a compression pressure in the cylinder, thereby obtaining a high absorption horsepower (braking force), which is called a compression-opening type engine brake. Compressive compression engine brakes of this kind are basically negative when the piston is lowered in the next combustion stroke by placing the compressed mixer in the cylinder in the exhaust system near the compression stroke top dead center of the internal combustion engine. ), Thereby obtaining a high absorption horsepower engine braking power.

Particularly, Japanese Patent Application Laid-Open No. 61-159639 discloses that this type of compression-opening engine brake is incorporated into an internal combustion engine equipped with the turbocharger (VG turbo) described above, thereby opening the compression pressure near the compression stroke top dead center. The technique which raises the compression pressure immediately before supercharging and thereby improves the absorption horsepower (braking effect) is disclosed.

However, according to the prior art, the compression-pneumatic engine brake incorporates a dedicated auxiliary exhaust valve (third valve) into the combustion chamber top, and forcibly opens the auxiliary exhaust valve separately from the timing specified in the normal combustion cycle. This is realized by. In other words, in addition to the intake valve and the exhaust valve, an auxiliary exhaust valve for a compression-pneumatic engine brake is further incorporated into the top of the combustion chamber. In a conventional pre-combustion engine, a pre-combustion apparatus is usually formed at the top of the combustion chamber.

Therefore, the port area (pot diameter of the valve) of each valve is naturally restricted, and the opening area of the auxiliary exhaust port opened and closed by the auxiliary exhaust valve is compared with the exhaust port opened and closed by the exhaust valve. You can't deny it getting noticeably smaller. Therefore, there is a problem that the braking effect described above cannot be obtained even when the compression pressure is improved by combining the above-mentioned VG turbo with the auxiliary pressure release type engine assist brake.

Incidentally, if the port opening area of the auxiliary exhaust valve for the compression-pneumatic engine brake is set large, theoretically, the opening effect of the compression pressure can be increased, so that the absorption horsepower during the compression-pneumatic engine brake is set large. Can be. In general, however, after determining the size of the intake valves or exhaust valves according to the specification of the output performance of the engine, the size of the auxiliary exhaust valves for the compression-pneumatic engine brakes is determined in view of the limitation of the size of these intake valves or exhaust valves. do. Therefore, the diameter of the auxiliary exhaust valve cannot be made large enough to match the relationship with the bore diameter of the cylinder, and the port opening area of the auxiliary exhaust valve must be set relatively small. For this reason, it is a fact that the capability of a compression compression engine brake is not brought out to the maximum.

In addition, even in the case of realizing a compression-opening engine brake using an exhaust valve, since the size of the exhaust valve itself is determined according to the size of the intake valve, the cylinder bore diameter, etc., the capability of the compression-opening engine brake also depends on this. It is hard to say that they are maximizing the capability of the compression-pneumatic engine brake. That is, since the size of the exhaust valve is determined according to the specification of the engine performance, it is difficult to say that the maximum compression-pressing engine brake effect can be obtained by the size.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide an engine auxiliary brake device capable of maximizing a compression-pressing engine brake effect.

In particular, the present invention increases the compression pressure in the cylinder by a supercharger using exhaust gas energy, and effectively discharges the high compression pressure, thereby fully exhibiting the action of the compression-opening type engine brake to obtain a high absorption horsepower, and the exhaust valve In addition, the present invention provides an engine assist brake system that can give design indexes of exhaust ports.

1 is a view showing a schematic configuration of a turbocharger attached engine to which the present invention is applied;

Figure 2 is a view showing the characteristics of the change in absorption horsepower with the change in port opening area for opening the compression pressure to the bore cross-sectional area of the cylinder,

3 is a view showing the configuration of intake valves, exhaust valves, and auxiliary exhaust valves in various engines, and the relationship between the valves that are opened for opening the compression pressure;

<Description of the symbols for the main parts of the drawings>

4: exhaust valve 4a: exhaust port

40: auxiliary exhaust valve 22: cylinder

121: exhaust turbine 122: intake compressor

151: variable nozzle

In order to achieve the above object, the engine auxiliary brake device described in the present invention comprises an exhaust turbine having a variable nozzle for changing a passage cross-sectional area of an exhaust system of an internal combustion engine and an exhaust turbine provided upstream of the internal combustion engine. And an intake compressor for supercharging the intake air, and having a communication cross section area of 6.5% or more for the bore cross section of the cylinder of the internal combustion engine, for example, for an exhaust valve or pressurized engine brake. And an exhaust communication means for communicating the cylinder with the exhaust system, and communicating the exhaust communication means in the vicinity of the exhaust stroke and compression stroke top dead center of the internal combustion engine in accordance with the operating state of the vehicle. While opening the compression pressure, the variable nozzle is directed to reduce the passage cross-sectional area of the exhaust system. And control means for operating.

That is, the present invention relates to an internal combustion engine including a turbocharger that supercharges using exhaust gas, and, in addition to the normal combustion cycle and timing depending on the operating state, specifically, the cylinder of the internal combustion engine in the vicinity of the compression stroke top dead center. A compression pressure opening means for driving an exhaust communication means, for example, an exhaust valve or an auxiliary exhaust valve for a compression-opening engine brake for selectively communicating with the exhaust system, to open the compression pressure in the cylinder; The communication cross-sectional area of the exhaust system of the exhaust communication means, for example, the port opening area, is set at 6.5% or more of the bore cross-sectional area of the cylinder at the time of pressure release.

EMBODIMENT OF THE INVENTION Hereinafter, the engine assist brake apparatus which concerns on one Embodiment of this invention with reference to drawings is demonstrated.

FIG. 1: shows the whole structure typically, and connects the exhaust side push rod 8 of arbitrary cylinders in the multi-cylinder engine 1, and the exhaust valve 4 of a cylinder different from this. It is typical sectional drawing cut along the flow path 11, and the sectional drawing of the cylinder from which right and left differs is shown on the basis of the broken line of the center of the rocker arm 10, respectively. The engine 1 is provided with a compression-pressure engine brake 100 and a turbocharger 102 that supercharges intake air by exhaust pressure. The engine auxiliary brake device according to the present invention is mainly constituted by the engine brake 100 and the turbocharger 102.

The brief description will be given of the compressed compression type engine brake 100. The engine brake 100 is configured in a manner similar to that of a conventional compressed compression type engine brake. That is, as shown in FIG. 1, the upper end of the exhaust side push rod 8 abuts the end of the exhaust side rocker arm 10 supported by the rocker shaft, while the lower end of the push rod 8 And a cam (not shown) rotated and driven in accordance with the rotation of the crankshaft. As a result, the push rod 8 reciprocates in the vertical direction in accordance with the rotational drive of the cam to swing the rocker arm 10.

In addition, the cylinder head 2 is provided with a valve bridge 5 which abuts two exhaust valves 4 and 4 and is capable of simultaneously opening and closing the exhaust valves 4 and 4 at the same time. The tip end of each rocker arm 10 is in contact with the valve bridge 5 described above. Therefore, when the rocker arm 10 swings, the exhaust valves 4 and 4 as the exhaust communication means are simultaneously opened and closed.

On the other hand, the exhaust push rod 8 of each cylinder and the exhaust valve 4 of the cylinder corresponding to it are connected via the flow path 11. This flow path 11 is connected to the push rod 8 of the cylinder which faces the exhaust stroke when the piston 21 of the cylinder shown in FIG. 1 came near compression stroke top dead center. As shown, a first oil sac 12a is formed at the push rod end of each flow path 11, and the first rod 12a is provided with a push rod 8 in the first oil chamber 12a. The master piston 12b which abuts and reciprocates in the said flow path 11 is inserted.

In addition, a second oil chamber 13a is formed in the oil passage 11 above one exhaust valve 4 of each cylinder, and the hydraulic pressure supplied through the oil passage 11 to the second oil chamber 13a. In accordance with this, a reciprocating slave piston 13b is provided. Further, below the slave piston 13b, an operating rod 17 that contacts the slave piston 13b and the exhaust valve 4 and transmits the driving force from the slave piston 13b to the exhaust valve 4 is disposed. It is. By this mechanism, the exhaust valve 4 can be driven independently of the rocker arm 10 in accordance with the drive of the slave piston 13b.

A check valve 14 and a solenoid valve 15 are disposed on the other end side of the flow path 11 (right side in the figure). The solenoid valve 15 is driven by a controller (ECU) 16 as its control means. In addition, the front side of the solenoid valve 15 is provided with a hydraulic oil supply part (not shown) which can supply hydraulic oil of predetermined pressure. In addition, when the high pressure hydraulic oil is supplied into the flow path 11 in accordance with the operation of the solenoid valve 15, the hydraulic pressure of the predetermined pressure is applied to the slave piston 13b. However, this hydraulic pressure is set to a pressure at which the slave piston 13b cannot be pushed down alone. Therefore, the operation of the compression-opening type engine brake 100 is achieved by turning on the solenoid valve 15 by the control signal from the controller 16 and supplying hydraulic oil of a predetermined pressure to each flow path 11 from the hydraulic oil supply part. do. At this time, the working oil is supplied into the flow passage 11 via the above-described check valve, so that the flow passage 11 is maintained at a predetermined pressure state.

On the other hand, in the first oil chamber 12a, the master piston 12b is reciprocally driven by the exhaust side push rod 8 to generate hydraulic pressure. By the operation of the master piston 12b, the pressure of the hydraulic oil supplied from the hydraulic oil supply portion is increased, and it operates on the slave piston 13b of the second oil chamber 13a. The slave piston 13b and the operating rod 17 are driven by this high-pressure working hydraulic pressure, that is, in accordance with the reciprocation of the master piston 12b. The operation of the slave piston 13b and the operating rod 17 causes the exhaust valve 4 to open and close at a different timing than the opening and closing timing by the rocker arm 10.

Reference numeral 19 shown in FIG. 1 denotes a flat spring for isolating the master piston 12b from the exhaust side push rod 8 when the solenoid valve 15 is turned off and the flow path 11 is at a low pressure. (Flat spring).

Herein, the opening / closing timing of the exhaust valves 4 and 4 of each cylinder at the time of the operation of the compression-pneumatic engine brake 100 will be described. As shown in FIG. The piston 21 closes immediately after passing the bottom dead center, and the compression process starts from this timing. On the other hand, when the transition from the compression stroke to the expansion stroke, that is, when the piston 21 is near the compression top dead center, the cylinder for starting the exhaust (in this case, the first oil chamber 12a of the flow path 11 is connected. The slave piston 13b is driven in accordance with the operation of the exhaust side push rod 8 of the cylinder, and the exhaust valves 4 and 4 are open-driven accordingly. Therefore, the air compressed at high pressure in the combustion chamber 20 by the piston 21 is discharged from the exhaust valves 4 and 4. Similarly, the exhaust valve of the other cylinder is also opened and closed in accordance with the drive timing of the exhaust side push rod of the cylinder corresponding thereto. By operating the exhaust valve 4 as described above in each cylinder, the compression work in the cylinder 22 increases, and the engine brake force of the engine 1 increases.

In addition, at the time of operation of the compression-push-out type engine brake 100, supply of fuel to a cylinder is stopped. In addition, an on-off switch for an engine brake device (not shown) is provided near a driver's seat (not shown), for example, and the driver operates the on-off switch to operate the compressed-push type engine brake 100. • Non-operation is to be switched.

As described above, the engine assist brake device is provided with a so-called turbocharger 102 which supercharges intake air by exhaust energy caused by exhaust pressure. The turbocharger 102 is mainly installed in the exhaust passage 103 of the engine 1 and rotates in response to the exhaust energy of the exhaust gas and the intake passage 104 of the engine 1. It is interposed and consists of an intake compressor 122 which rotates by the rotational force of the exhaust turbine 121 and compresses the intake air (intake).

A turbine housing 103A is formed on the exhaust passage 103, and the exhaust turbine 121 is provided in the turbine housing 103A. Similarly, a compressor housing 104A is formed in the intake passage 104, and an intake compressor 122 is provided in the compressor housing 104A. In addition, the exhaust turbine 121 and the intake compressor 122 are connected by the turbine shaft 123, and the intake compressor 122 is rotated by the rotation speed according to the rotation speed of the exhaust turbine 121. As shown in FIG.

By the way, the above-mentioned turbine housing 103A is provided with exhaust throttle means 105 for adjusting the speed of the exhaust gas colliding with the exhaust turbine 121. As shown in FIG. 1, this exhaust throttle means 105 consists of the variable nozzle 151 attached to the turbine housing 103A, and the actuator 152 which adjusts the opening degree of this variable nozzle 151. As shown in FIG. The operation of the actuator 152 is controlled based on the operation control signal from the controller (ECU) 16 as the control means. By closing the opening degree of the variable nozzle 151 controlled in this way, the flow velocity of the exhaust gas which collides with the exhaust turbine 121 becomes high, and conversely, by opening the opening degree of the variable nozzle 151, the flow rate of exhaust gas becomes slow. do. The variable nozzle 151 of the exhaust turbine 121 is called VG (variable guide vane).

Incidentally, the variable nozzle 151 consists of a plurality of nozzle vanes arranged at equal intervals around the turbine blades of the exhaust turbine 127, for example, and the exhaust gas flow rate ( Exhaust gas velocity). The variable adjustment of the variable nozzle (nozzle vane) 151 is made by driving the actuator 152 under the control of an engine control unit (ECU) 16 which controls the operation of the internal combustion engine in accordance with the driving state of the vehicle.

On the downstream side of the intake compressor 122, a boost pressure sensor 172 for detecting the compressed pressure (boost pressure) of the intake air compressed by the compressor 122 and guided into the intake manifold 104 is incorporated. . The ECU 16 includes information such as boost pressure detected by the boost pressure sensor 172, accelerator opening degree information for controlling the operation of the engine, information of a brake switch indicating braking operation, engine speed, and the like. And the driving state of the vehicle is monitored by comprehensively judging this information. The ECU 16 controls the operation (operation of the actuator 152) of the exhaust turbine 121 in accordance with the driving state of the vehicle, and drives the exhaust valve 4 to drive the exhaust valve 4, ( 4) is opened and the compression pressure in the cylinder 1 is released.

However, in the internal combustion engine (engine) comprising the turbocharger 102 and the compression compression engine brake 100 as described above, the engine assist brake device according to the present invention is characterized by a compression stroke boss. Set the communication cross-sectional area of the exhaust system in which the cylinder 22 is in communication with the exhaust system to open the compression pressure in the cylinder 22 near the point is set to 6.5% or more of the bore cross-sectional area defined by the bore diameter of the cylinder 22. It is characterized by one.

That is, for example, when only the exhaust valves 4 and 4 are opened to open the compression pressure in the cylinder 22 to act on the compression-opening type engine brake 100, the exhaust valves 4 and 4 The cross-sectional area of the exhaust passage communicating with the exhaust system, specifically, the port opening area in the auxiliary exhaust port 4a is set to 6.5% or more of the bore end area of the cylinder 22. In other words,

[Port opening area / bore area] × 100% ≥ 6.5%

Is set in relation to

FIG. 2 shows the change in absorption horsepower when the ratio of the port opening area to the bore cross-sectional area for releasing the compression pressure of the cylinder 22 is changed. In addition, the solid line A is a change characteristic of the absorption horsepower in the case of the turbocharger (VG turbo 102) with a turbocharger with a variable nozzle, and the broken line B is a change characteristic of the absorption horsepower in the case of no turbocharge. As shown in Fig. 2, particularly in the case of supercharging, when the opening area of the exhaust port is set to 6.5% or more with respect to the bore end area of the cylinder 22, the effect of increasing the absorption horsepower is almost saturated. Under these conditions, the maximum compression compression engine brake effect can be obtained.

In other words, in order to maximize the engine brake effect by opening the compression pressure, the engine design may be performed so that the port opening area for releasing the compression pressure of the cylinder 22 is 6.5% or more of the bore cross-sectional area. For example, when the port opening area is less than 6.5% of the bore area, the maximum absorption horsepower cannot be obtained, and the braking characteristic of the engine itself cannot be sufficiently exhibited. In addition, as indicated in the prior art, an auxiliary exhaust valve having a smaller diameter than the exhaust port is taken as an example, and the diameter of the auxiliary exhaust port is designed to be about 5.5 mm with respect to the bore diameter 130 mm of the cylinder 22. The opening area of the auxiliary exhaust port occupies only 0.17% of the bore cross section. Therefore, it is possible to obtain some compression compression engine brake effect, but it is difficult to say that the maximum absorption horsepower is obtained by the compression opening.

Therefore, according to the above-described engine for opening the compressed pressure, for example, the port opening area opened by the auxiliary exhaust valve 8 to be 6.5% or more of the cross-sectional area, the absorption horsepower is sufficiently increased to maximize the maximum. Compression and compression engine brake effect can be obtained. In particular, by using a turbocharger (VG turbo 102) with a variable nozzle, high absorption horsepower can be obtained together with the supercharge effect. In other words, when the pot opening area is increased from 0.17% of the cross-sectional area to 6.4%, the increase in absorption horsepower is significantly greater in the case where the VG turbo 102 is used in combination, and the compression-pressure engine brake capability is fully exhibited. Can be.

That is, when the on / off switch is turned on by the driver's operation, the operation control signal of the variable nozzle 151 is output from the ECU 16 to the actuator 152, whereby the variable nozzle 151 is closed. Works in the direction of At the same time, the compression-pressure engine brake 100 also operates to open one exhaust valve 4 near the compression stroke top dead center, which is a timing other than the exhaust process. As a result, the intake compressor 122 is driven at a high speed rotation to supercharge the intake air, and a large amount of intake air is introduced into the cylinder 22. In the timing near the compression stroke top dead center, since a large amount of intake air in the cylinder 22 is discharged at once from the exhaust port 4a, which is set to 6.5% or more of the bore area as described above. Great braking force can be obtained.

In addition, according to the present invention, since the opening area of the exhaust port is set to 6.5% or more of the bore area, the maximum compression press method brake effect can be exhibited. The design index of the valve and the exhaust port can be effectively set by setting the opening area of the exhaust port to 6.5% or more of the cross-sectional area as described above.

In addition, this invention is not limited to the above-mentioned embodiment, It is applicable to the engine of various types from which a valve structure differs. For example, as shown in Fig. 3 (a), it can be similarly applied to an engine which simultaneously opens two exhaust valves 4 and 4 to realize a compression-pneumatic engine brake. As shown in Fig. 3B, the exhaust valve 4 and the auxiliary exhaust valve 40 opened only at the time of the operation of the compression-pneumatic engine brake 100 are simultaneously opened to realize a compression-pneumatic engine brake. It is also applicable to the engine. In this case, the bore of the cylinder 22 sums the sum of the port opening areas of the cross-sectional exhaust port of the exhaust passage communicated with the exhaust system by the exhaust valves 4 and 40 and the auxiliary exhaust port. You can set it to 6.5% or more of the cross-sectional area.

As shown in Fig. 3 (c), the engine is provided with two intake valves 50 and two exhaust valves 4, and only one exhaust valve 4 is opened to realize a compression pneumatic engine brake, or As shown in FIG.3 (d), it is applicable also to the engine provided with the intake valve 50 and the exhaust valve 4 one by one, and equipped with the auxiliary exhaust valve 40 exclusively for compression-pressure engine brake. For example, when the bore diameter of the cylinder 1 is 130 mm and only one auxiliary exhaust valve 40 provided independently of the exhaust valve 4 is opened to release the compression pressure, thereby obtaining absorption horsepower. What is necessary is just to set the diameter (opening port diameter) of the auxiliary exhaust port opened by the said auxiliary exhaust valve 40 to about 33.5 mm.

In addition, as shown in FIG. 3 (e), only one pair of intake valves 50 and exhaust valves 4 are provided, and the exhaust valves 4 are opened to be applied to an engine that realizes a compression pneumatic engine brake. In this case, the port opening area of the exhaust port 4a in the cross-sectional area of the exhaust passage communicated with the exhaust system by the exhaust valve 4 may be set to 6.5% or more of the bore end area. In addition, this invention can be variously modified and implemented in the range which does not deviate from the summary.

As described above, according to the engine assist brake apparatus according to the present invention, in an engine equipped with a turbocharger for supercharging intake air using an exhaust turbine whose exhaust gas flow rate is variable, the communication cross-sectional area of the cylinder with respect to the bore cross section of the cylinder is determined. For example, the exhaust communication means having an exhaust port opening area of 6.5% or more is provided, the exhaust communication means is driven in accordance with the driving state of the vehicle, and the exhaust turbine is rotated at high speed to supercharge the intake air. Since the absorbed horsepower is obtained by opening the supercharged high compression pressure, it is possible to obtain the maximum compression-pressure engine brake effect easily and effectively. In addition, the above design index can be effectively given to obtain the maximum compression compression engine brake effect.

Claims (1)

An exhaust turbine 121 installed in the exhaust system of the internal combustion engine 1, A variable nozzle 151 which is provided upstream of the exhaust turbine 121 to change the passage cross-sectional area of the exhaust system; An intake compressor 122 for supercharging the intake air to the internal combustion engine 1 in conjunction with the exhaust turbine 121, exhaust communication means for communicating the cylinder 22 of the internal combustion engine 1 with the exhaust system; According to the driving state of the vehicle, the exhaust communication means is connected in the vicinity of the exhaust stroke and the compression stroke top dead center of the internal combustion engine 1 to open the compression pressure in the cylinder 22, and the variable nozzle 151 In the engine auxiliary brake device having a control means for operating in a direction in which the passage cross-sectional area of the exhaust system is small, An engine assist brake device, characterized in that the communication cross section of said exhaust communication means to said exhaust system is set to be 6.5% or more with respect to the bore cross section area of the cylinder (22) of said internal combustion engine (1).