JPH0229239Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a device for controlling exhaust gas from an exhaust passage connected to a combustion tube of an engine.

Normally, in order to ensure its output, the engine
The ventilation resistance of the exhaust pipe, muffler, etc. is kept low to prevent excessive exhaust pressure. However, when a car equipped with an engine requires braking force, rotational force due to the inertia of the car body is applied from the wheel side to the engine, causing the engine to suffer pumping losses and act as a so-called engine brake. . As a device that can deal with such cases,
Exhaust brakes are known that actively close exhaust passages to increase engine pumping losses. This exhaust brake uses a valve that opens and closes the exhaust passage by operating a switch, thereby controlling the exhaust pressure. On the other hand, as a means to improve the startability of the engine at low temperatures, it suppresses the amount of exhaust gas discharged from the combustion cylinder and retains relatively high-temperature residual gas within the combustion cylinder, thereby keeping the gas temperature in the cylinder high. Cold start assist devices that stabilize combustion are known.

By controlling the exhaust flow rate through the exhaust passage in this manner, the engine is more effectively and easily utilized. By the way, an exhaust path control device that changes the cross-sectional area of the exhaust path includes a valve that opens and closes the exhaust path. This valve is connected to a valve operating means that applies an operating force to it, and changes within a set range by receiving an opening/closing operating force from a movable member such as a piston that reciprocates a set stroke in response to operating gas. However, this movable member remains in its home position when not receiving working gas, and changes by a set amount when receiving working gas. For this reason, the on-off valve only connects and disconnects the exhaust path, and cannot control the exhaust pressure and flow rate to the desired amount.In particular, this valve is used to form a low-temperature starting assist device that also serves as an exhaust brake. In such cases, inconveniences occur. In other words, the valve used in this low-temperature start assist device seals the exhaust passage when the exhaust braking function is activated, and secures a small opening area necessary to continue driving the engine when the low-temperature start function is activated. Must be. However, the conventional device uses a two-position opening/closing valve that maintains the opening/closing valve at an extremely small opening degree, which compromises these conflicting demands. For this reason, the exhaust brake does not work satisfactorily, and furthermore, if it operates as a low-temperature start assist device, black smoke may be generated due to an excessive increase in exhaust pressure and a reduction in the amount of intake air.

The object of this invention is to provide an engine exhaust control device in which a valve body that changes the opening area of an exhaust passage can accurately maintain not only fully open and fully closed positions but also intermediate opening degrees.

The engine exhaust control device according to this invention includes a valve body that crosses the exhaust passage of the engine to open and close the exhaust passage, and a groove that guides the valve body in the cross direction of the exhaust passage. a cylinder that is attached to the valve support and has a working gas receiving chamber to which working gas is supplied; A movable member connected to the main body via a rod, an elastic member that applies an urging force in a direction opposite to a direction of movement of the movable member by the working gas stored in the cylinder, and the movable member are set. elastic force applying means for generating an elastic force on the movable member that is added to the elastic force of the elastic member when the movable member reaches the intermediate position; a first supply means for supplying a working gas capable of applying pressure in a direction to fully close the valve body against the resultant force of elastic forces; and a first supply means communicating with the working gas receiving chamber. A pressure regulating valve is provided for supplying a predetermined amount of working gas with a pressure returned to the atmospheric pressure side relative to the pressure of the supplied working gas, and the resultant force of both the elastic forces of the elastic member and the elastic force applying means is provided by the equalizing pressure valve. and a second supply means for supplying working gas at a pressure that balances the movable member at the intermediate position, and the valve body is moved to the intermediate opening position by supplying the working gas from the second supply means. It is characterized by being held at.

According to such an engine exhaust control device,
The movable member moves to a position where the working force of the working gas and the elastic force in the opposite direction to this working force are balanced, but the working gas is supplied from the second supply means and the movable member reaches the set intermediate position. At this time, an additional elastic force is applied to the movable member in addition to the elastic force. Therefore, the movable member reaches the intermediate position in a range where the amount of displacement per unit actuation force is small. That is, even if there is a slight deviation in the operating force, the movable member is held at the intermediate position without deviation, and the on-off valve can be held at the desired intermediate opening degree with high precision.

This invention will be explained below with reference to the accompanying drawings.

FIG. 1 shows an engine exhaust control device (hereinafter simply referred to as an exhaust control device) 1 as an embodiment of this invention. This exhaust control device 1 is attached to an exhaust pipe 3 of a diesel engine 2. The exhaust control device 1 together with a negative pressure gas supply means 6 that supplies negative pressure gas as a working gas, forms a low temperature starting assist device 4 which also serves as an exhaust brake.

As shown in FIG. 2, the exhaust control device 1 includes a guillotine-type valve (hereinafter simply referred to as a valve body) 5 that slides to open and close an exhaust passage R in an exhaust pipe 3, and a guillotine-type valve (hereinafter simply referred to as a valve body) 5 that is connected to the exhaust passage R. a valve support 7 formed with a groove 14 guiding in the cross-sectional direction A perpendicular to the centerline;
Cylinder 8 integrally attached to this valve support
, a piston 9 as a movable member housed in this cylinder so as to be slidable in the direction of its center line l, and a working gas receiving chamber (hereinafter referred to as An inner coil spring (hereinafter simply referred to as an inner spring) 11 which generates an elastic force F1 in the opposite direction to the operating force F applied by the negative pressure gas of the 10 (hereinafter simply referred to as a receiving chamber) to the piston 9; It is formed of an outer coil spring (hereinafter simply referred to as an outer spring) 12. The piston 9 is integrally connected to the valve body 5 via a rod 13.
The inner spring 11 of the inner and outer springs 11 and 12, which are doubly fitted around the rod 13, allows the piston 9 to fully open when the valve body 5 is fully open as shown in FIG. 3a. An elastic force is applied to position the camera at the home position P1. On the other hand, as shown in FIG. 3b, when the valve body 5 shows an intermediate opening degree that forms a warm-up gap x1 necessary to continue warming up the engine, the piston 9 is at the set intermediate position P0. To position. At this time, the outer spring 12 as well as the inner spring 11 comes into contact with the piston 9, and the elastic force F1 of the inner spring 11
In addition, additional elastic force F2 of the outer spring 12 is also applied.

The negative pressure gas supply means 6 is a vacuum tank 15
, first and second supply pipes 16 and 17 as first and second supply means for supplying negative pressure gas from the vacuum tank 15 to the receiving chamber 10;
and first and second attached to the second supply pipe.
A regulator is connected in series with the three-way solenoid valves 18 and 19 and the second three-way solenoid valve 19, and regulates the pressure by returning a predetermined amount of negative pressure gas to the atmospheric pressure side, that is, supplies negative pressure gas whose pressure has been adjusted to increase. Pressure valve 20 and first three-way solenoid valve 18
It is formed of a low temperature start control circuit 21 and an exhaust brake switch circuit 22 which are connected in parallel to each other (see FIG. 1).

The low temperature start control circuit 21 is the diesel engine 2
is connected to a rotation speed detector 211 that emits a rotation speed signal So corresponding to the rotation speed of 500
If it is in the first setting range a1 of [rpm], the fully closed signal I1
is applied to the first three-way solenoid valve 18. Furthermore, if the rotational speed signal So is in the second setting range a2 of 500 to 1000 [rpm], a starting assist signal I2 is given to the second three-way solenoid valve 19. The first three-way solenoid valve 18 is connected to the switch circuit 2
When the exhaust brake switch 221 in the exhaust brake switch 2 is turned on, the fully closed signal I1 is received, and as shown in FIG.
The high level negative pressure gas from the vacuum tank 15 is passed through as it is. On the other hand, the second three-way solenoid valve 19 is turned on in response to the starting assist signal I2 issued by the low-temperature starting control circuit 21, and as shown in FIG. Switch connection to 173. The pressure regulating valve 20 regulates the negative pressure gas at the high level pressure P1 supplied from the vacuum tank 15 via the second three-way solenoid valve 19 to a desired pressure value (here, 7 [Kg/cm ² ]). It is sufficient if the pressure is regulated to about 3 to 3 [Kg/cm ² ]. In addition, the operating force F (P0) due to the corrected pressure P0 after pressure adjustment
The pressure regulating valve 20 is adjusted so that the piston 9 is held at the intermediate position P0 when the force F2 is balanced with the resultant force of the elastic force F1 and the additional elastic force F2.

The operation of the exhaust control device 1 shown in FIG. 1 will be explained together with the operation of the negative pressure gas supply means 6.

First, when the diesel engine 2 starts, the low temperature start control circuit 21 of the negative pressure gas supply means starts operating. This low temperature start control circuit 21 outputs a fully closed signal I1 when detecting a cooling water temperature T below a set value and a first set range a1 (see FIG. 5). Then, the first three-way solenoid valve 18 is turned on,
Actuation force F due to negative pressure gas of pressure P1 on piston 9
(P1) acts, and the piston 9 is moved by the inner and outer springs 11,
It slides through a stroke L1 against 12 elastic forces F1 and F2. As a result, the valve body 5 is maintained at the closed opening position (see FIG. 3c). Therefore, the exhaust pressure increases, and the residual gas keeps the gas temperature in the cylinder of the diesel engine 2 high, allowing the engine to continue moving relatively smoothly. Eventually, when the second setting range a2 is entered, the low temperature start control circuit 21 outputs the start assist signal I2 instead of the fully closed signal I1. Then, the second three-way solenoid valve 19 is turned on, and the negative pressure gas having the pressure P0 that has passed through the pressure regulating valve 20 applies an operating force F (P0) to the piston 9. Then, the piston 9 slides through the stroke a and stops at the intermediate position P0. In this case, the piston 9 has an operating force F(P0)
and the resultant force of the elastic forces F1 and F2 are held at an intermediate position P0 as a balance position.

As the rotational speed further increases, the exhaust pressure starts to rise again (see Figure 5), the in-cylinder gas temperature also rises, heating of the diesel engine itself is promoted, and the rotational speed continues to rise. This warm-up is completed quickly because the cylinder temperature is kept high by the residual gas. At this time, the cooling water temperature T exceeds the set value. At this point, the low temperature start control circuit 21 outputs the start assist signal I.
Stop 2. Then both solenoid valves 18,1
9 communicate the receiving chamber side ports 161, 171 with the atmosphere opening ports 162, 172, and then reach the closed position. As a result, the piston 9 is moved by the inner and outer springs 1
1 and 12 returns to the home position P1 (see FIG. 3a). The diesel engine 2 that has been warmed up in this manner then enters steady operation.
On the other hand, in the diesel engine 2 in steady operation, when the exhaust brake switch 221 is turned on, the first three-way solenoid valve 18 receives the fully closed signal I1, and the valve body 5 is maintained at the closed opening position (see Fig. 3c). be done. Then, the exhaust pressure rises rapidly, and the diesel engine 2 is forcibly rotated by the inertia of the vehicle, causing a pump loss, which causes the exhaust brake to work accurately.

In this way, the exhaust control device 1 can maintain the valve body 5 at an intermediate opening degree other than fully closed or fully open.
Moreover, by using the outer spring 12 as the elastic force applying means as shown in FIG. 4a, the composite spring constant at the intermediate position P0 is increased. Therefore, even if the pressure value P0 of the negative pressure gas passing through the second supply pipe 17 deviates from the set value to some extent, the amount by which the piston 9 deviates from the intermediate position P0 is kept low due to the deviation. (FIG. 4b shows the case of a single coil spring), and the piston 9 can be easily held at the set intermediate position P0 with high precision. Therefore, by using this exhaust control device 1, it is possible to form a low-temperature start assist device 4 that accurately exhibits both exhaust braking performance and low-temperature start assist performance.

The exhaust control device 1 shown in FIG. 1 uses an outer spring 12 fitted onto the inner spring 11 as an elastic force applying means, but as shown in FIG. good. In this case, the nonlinear coil spring 23 has a central portion 231 and upper and lower ends 232.
The pitch between the two ends is unequal, and the upper and lower ends 232 act as elastic force applying means. That is, when the actuation force F acts on the piston 9, first, the center portion 231 is greatly compressed, and the upper and lower ends 232 are compressed very slightly. Eventually, when the pitch between the center portion 231 and the upper and lower ends 232 becomes equal, the whole is compressed by the same amount. In this region where the whole changes by the same amount, the spring constant becomes large (see FIG. 7), and the amount of variation of the piston 9 per unit actuation force F becomes small. For this reason,
Even when this nonlinear coil spring 23 is used, as with the inner and outer springs 11 and 12 described above, an elastic force F with a large spring constant acts on the piston 9 that reaches the intermediate position P0. Therefore, even if the pressure value of the negative pressure gas deviates somewhat, the piston 9 is easily held at the set intermediate position P0.

The outer spring 12 used in the exhaust control device 1 shown in FIG. 1 had a free length when the piston 9 was not in contact with it, but instead of this outer spring 12, a set force as shown in FIG. An outer spring 12 with attached member 24 may also be used. In this case, the outer spring 12 is subjected to a set force F4, and even if it comes into contact with the piston 9, a pressure value P2 that causes the piston to generate an operating force exceeding this set force F4 is applied.
The compression will not fluctuate unless negative pressure gas is applied (see Figure 9). Therefore, if the value p0 is set with the pressure reducing valve 20 (see Figure 1) so that the piston 9 maintains the intermediate position P0 at the value immediately before the pressure value p2, the piston 9 will be kept at the intermediate position P0 from now on.
Even if there is a deviation in p0, the intermediate position P
It has the advantage of being kept at 0. The set force imparting member 24 used here consists of a pair of cylindrical bodies 241 and 242 which are upper and lower parts and which are fitted concentrically to each other.
It is. Moreover, both the cylindrical bodies 241 and 242 are engaged with each other via opposing hook parts 243 and 244,
The length of the outer spring 12 is regulated. In place of these two cylindrical bodies, the set-force applying member may be formed by using a plurality of annular tapes 245 having sufficient durability against tension, as shown in FIGS. 10a and 10b.

In the exhaust control device 1 shown in FIG. 1, the low-temperature start control circuit 21 sends out the fully closed signal I1 and the start assist signal I2, but instead of this, a manual switch may be used. Further, although the exhaust control device 1 uses negative pressure gas, positive pressure gas may be used instead.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view of a diesel engine equipped with an exhaust control device as an embodiment of this invention, Fig. 2 is an enlarged schematic view of the same exhaust control device, and Fig. 3 is a diagram of a piston used in the above exhaust control device. Operation explanatory diagram, Fig. 4a is a valve opening-negative pressure value diagram, Fig. 4b is a conventional valve opening-negative pressure value diagram, and Fig. 5 is an exhaust pressure-rotational speed diagram of the same diesel engine. Fig. 6 is a side view of a nonlinear coil spring used in an exhaust control device as another embodiment of this invention, and Fig. 7 is a valve opening-negative pressure value diagram used in the exhaust control device of Fig. 6. , FIG. 8 is a side sectional view of a set force applying member used in an exhaust control device as another embodiment of this invention, and FIG. 9 is a valve opening degree-negative pressure value diagram of the valve body shown in FIG. 8. , and FIG. 10 respectively show explanatory views of other members used as the set force imparting member. DESCRIPTION OF SYMBOLS 1... Exhaust control device, 2... Diesel engine, 5... Valve body, 9... Piston, 10... Receiving chamber, 11... Inner spring, 12... Outer spring, 15...
Vacuum tank, 16... First supply pipe, 17...
...Second supply pipe, 23...Nonlinear coil spring, 20
...Pressure regulating valve, R...Exhaust path, P0...Intermediate position,
F... Actuation force, F1, F3... Elastic force, F2...
Additional elastic force.

Claims (1)

[Scope of utility model registration request] a valve body that opens and closes the exhaust passage across the exhaust passage of the engine; a valve support body in which a groove is formed in the exhaust passage for guiding the valve body in the cross direction of the exhaust passage; a cylinder having a working gas receiving chamber attached to the cylinder and supplied with working gas;
A movable member is slidably housed inside the cylinder and connected to the valve body via a rod, and the movable member is slidably housed inside the cylinder by the working gas. an elastic member that applies a biasing force in a direction opposite to the direction of movement; and an elastic force that applies an elastic force to the movable member that is added to the elastic force of the elastic member when the movable member reaches a set intermediate position. means and
A first supply that communicates with the working gas receiving chamber and supplies working gas capable of applying pressure in the direction of fully closing the valve body against the resultant force of the elastic force of the elastic member and the elastic force applying means. and a pressure regulating valve communicating with the working gas receiving chamber and supplying a pressure of a predetermined amount of working gas returned to the atmospheric pressure side relative to the pressure of the working gas supplied by the first supplying means; a second supply means for supplying working gas at a pressure that balances the resultant force of both the elastic forces of the elastic member and the elastic force applying means and holds the movable member at the intermediate position using a synchronized pressure valve; An exhaust gas control device for an engine, wherein the valve body is maintained at an intermediate opening degree by supplying working gas from a supply means.