JPH0649864Y2 - Intake device for V-type multi-cylinder internal combustion engine - Google Patents

Description

[Detailed Description of the Invention] A. Purpose of the Invention (1) Field of Industrial Application The present invention, in a V-type multi-cylinder internal combustion engine, controls the intake pressure fluctuation by making the passage length of the intake system variable.
The present invention relates to an improvement of an intake device that aims to improve the volumetric efficiency of the engine.

(2) Related Art In an intake system of a conventional multi-cylinder internal combustion engine, it is used that a negative pressure wave generated at the start of intake in each cylinder is reflected by a volume expansion part provided in the intake system and returned to the intake port side. There have already been proposed various intake devices which exhibit the above-mentioned inertial effect and enhance the volumetric efficiency from the low speed to the high speed region of the engine (for example, see JP-A-61-226515).

The above intake device communicates a plurality of cylinders of a multi-cylinder internal combustion engine with the first volume expanding section via independent distribution pipes for each cylinder,
Further, the upstream side of the first volume expanding section is connected to the atmosphere via a throttle valve, and the intermediate section of the distribution pipe is connected to the second volume expanding section via a short branch passage to operate the engine in the branch passage. A pipe length switching valve that is controlled to open and close according to the state is provided, and by controlling the opening of the pipe length switching valve, the second volume enlargement portion and each cylinder are made to communicate with each other through a straight short passage. Has been done.

Therefore, by closing the pipe length switching valve in the low speed operation range of the engine, an inertia supercharging system having a long passage communicating with each cylinder through the entire length of the distribution pipe to the first volume expanding portion is formed. By improving the volumetric efficiency in the low speed operation range of the engine, and by opening the pipe length switching valve in the high speed operation range of the engine,
An inertial supercharging system having a short passage communicating with the second volume expanding portion from each cylinder through the downstream portion of the distribution pipe and the branch passage is provided to improve the volumetric efficiency in the high speed operation range of the engine. . Then, in the high-speed operation range, the second volume expansion section and each cylinder are communicated with each other via a linear passage to increase the propagation speed of the pressure wave and to increase the volume efficiency in the high-speed operation range to a higher value. It is supposed to be secured.

(3) Problem to be Solved by the Invention By the way, the above conventional intake system is applied to an in-line multi-cylinder internal combustion engine, and is for installing the intake system in a narrow V space of a V-type multi-cylinder internal combustion engine. No special consideration has been given.

The present invention has been made in view of the above-mentioned circumstances, and a V-type multi-cylinder internal combustion engine having an intake device in which the length of the distribution pipe connected to each cylinder of the multi-cylinder internal combustion engine is variable via a pipe length switching valve. The purpose is to rationally lay out in a narrow V space.

B. Configuration of the Invention (1) Means for Solving the Problems According to the present invention, in order to achieve the above-mentioned object, a plurality of distribution pipes whose downstream ends are respectively connected to the left and right cylinder groups, and the operation of the engine. In a V-type multi-cylinder internal combustion engine intake device in which a pipe length switching chamber, which communicates with an intermediate portion of the distribution pipe through a pipe length switching valve that is controlled to open and close according to the situation, is arranged in a V-shaped space, It is curved in an inverted U shape and the pipe length switching chamber is provided on the upper part thereof, the downstream side of the distribution pipe is linearly connected to the left and right cylinder groups, and the outer wall surface of the curved portion of the distribution pipe is The first feature is that the pipe length switching chamber and the left and right cylinder groups are communicated with each other through a linear passage by forming an opening that communicates with the pipe length switching chamber.

In addition to the first feature of the present invention, when a pipe length switching valve having a butterfly type valve body is attached to the opening and the opening is opened to connect the pipe length switching chamber to the left and right cylinder groups. The second feature is that the valve element is rotated to a position parallel to a passage connecting the pipe length switching chamber and the left and right cylinder groups.

(2) Operation According to the first feature, when the pipe length switching valve is controlled to be closed in the low speed operation range of the engine, the communication between the respective distribution pipes and the pipe length switching chamber is cut off, and the entire length of each distribution pipe is effectively intake. Functions as a passage. As a result, a supercharging system having a relatively small natural frequency is formed, and the volumetric efficiency in the low speed operation range of the engine is improved. On the other hand, when the pipe length switching valve is controlled to open in the high speed operation region of the engine, each distribution pipe communicates with the pipe length switching chamber through the opening formed in the intermediate portion. As a result, a supercharging system having a relatively large natural frequency is formed, and the product efficiency in the high speed operation range of the engine is improved.

By providing a pipe length switching chamber on the upper portion of the distribution pipe curved in an inverted U shape, the space in the V space can be effectively utilized, and the downstream side of the distribution pipe is linearly left,
By connecting to the right cylinder group and forming an opening in the outer wall surface of the curved portion of the distribution pipe that communicates with the pipe length switching chamber, the pipe length switching chamber and the left and right cylinder groups are communicated via a straight passage. The volumetric efficiency can be improved by increasing the propagation speed of the pressure wave.

According to a second feature of the present invention, the valve body that opens and closes the opening is of a butterfly type, and in its open position, the valve body is rotated to a position parallel to a passage connecting the pipe length switching chamber and each cylinder. Therefore, the pressure wave is smoothly propagated between the pipe length switching chamber and each cylinder in the high speed operation range, and higher volume efficiency is secured.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings.

1 to 7 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a main part of a V-type 6 cylinder internal combustion engine equipped with the device of the present invention, and FIG. 2 is a plan view of its cylinder block. 3 is an enlarged partial plan view taken along the line III-III in FIG. 1, FIG. 4 is an enlarged partial plan view taken along the line IV-IV in FIG. 1, and FIG.
FIG. 4 is a cross-sectional view taken along the line VV, FIG. 6 is FIG.
Sectional drawing which follows the line, FIG. 7 is sectional drawing which follows the VII-VII line of FIG.

In FIGS. 1 and 2, the engine body E of the 6-cylinder internal combustion engine is shown.
Is equipped with a pair of left and right engine blocks Bl, Br which are arranged in a V shape with each other. The left and right engine blocks Bl, Br are respectively joined to the cylinder blocks 1, 1r and their deck surfaces. , Which have three cylinders 2l, 2R, three left cylinders 3l are formed in series in the left cylinder block 1, and three cylinders 3r are also formed in the right cylinder block 1r.
Are formed in series. The three left cylinders 3l ... constitute a left cylinder group Cl in which the intake stroke is not continuous, that is, the intake valves 10 do not overlap, and the three right cylinders 3r ...
Also constitutes the right cylinder group Cr in which the intake stroke is not continuous, that is, the intake valves 10 described later do not overlap.

Pistons 4 are slidably fitted in the left and right cylinders 3l ..., 3r ... as usual, respectively.
Is linked to the crankshaft 6 via the connecting rod 5. Further, the left and right cylinder heads 2l and 2r are respectively formed with a combustion chamber 7 facing the piston 4 and intake and exhaust ports 8 and 9 communicating with the combustion chamber 7, and each intake port 8 has
An intake valve 10 for opening and closing the port 8 is provided, and an exhaust valve 11 for opening and closing the port 9 is provided for each exhaust port 9.
Are provided respectively. The intake / exhaust valves 10 and I1 are opened / closed at a predetermined timing by a conventionally known valve operating mechanism 12.

Intake ports 8 of the left and right cylinder heads 2l, 2r
An intake system In, which will be described in detail later, is connected to ... And a conventionally known exhaust system (not shown) is connected to the plurality of exhaust ports 9 of the left and right cylinder heads 2l and 2r.

Next, the structure of the intake system In will be described in detail with reference to FIGS. 2 to 7. The intake system In is disposed in the V space C between the left and right engine blocks 1 and 1r, and the air cleaner Ac
And the intake passage Pi connected to the outlet of this air cleaner Ac.
A box-shaped volume expansion portion Bg having a pair of left and right resonance chambers Cr-l, Cr-r connected to the downstream end of the intake passage Pi, and intake air of the left and right cylinder blocks 1, 1r. The left and right resonance chambers Cr-l, Cr-r are joined to the end faces where the ports 8 are opened, and the intake manifold Mi for communicating the left and right cylinder groups Cl, Cr respectively.

The intake passage Pi is provided with an air cleaner Ac as shown in FIG.
At the downstream end of the upstream intake passage 14
A downstream side intake passage 16 is integrally connected via 15. The upstream intake passage 14 is formed of a hollow cylinder to suck intake air from the air cleaner Ac, and has a throttle body.
The axial end of 15 is fixed to the upstream intake passage 14 and the downstream intake passage 16 by bolts 17, ..., 18, respectively, and a throttle valve 20 whose opening / closing is controlled by an operating portion 19 is provided inside thereof.

The downstream side intake passage 16 has a rectangular cross section and extends along the direction of the crankshaft 6 of the engine, and the inside thereof is a partition wall.
Left and right branch resonance passages 22l, 22r parallel to each other by 21
It is divided into The left and right branch resonance passages 22l,
The upstream end of 22r is connected to the throttle body 15. An opening / closing valve 23 is provided in the partition wall 21 near the downstream side of the downstream side intake passage 16. That is, the partition wall
21 is provided with a valve holder 25 that opens a valve port 24 that communicates the left and right branch resonance passages 22l, 22r.
A valve shaft 26 extending along the axial direction of the downstream side intake passage 16 is rotatably supported, and a rectangular plate-shaped valve body 27 for opening and closing the valve port 24 is fixed to the valve shaft 26 with screws 28. ing. One end of the valve shaft 26 penetrates the end wall of the valve holder 25 and projects to the outside of the downstream side intake passage 16, and a conventionally known actuator 29 is connected to the projecting end. The actuator 29 is actuated and controlled according to the operating state of the engine to open / close the opening / closing valve 23. The on-off valve 23 is sometimes controlled to open.

On the left and right sides of the downstream side intake passage 16, the left and right resonance chambers Cr- of the volume expansion part Bg are arranged so as to sandwich the intake passage 16.
l, Cr-r are formed integrally in parallel with the downstream side intake passage 16.

As shown in Figs. 1 and 5, the left and right resonance chambers Cr-l, Cr-r
Also, the downstream side intake passage 16 is integrally formed inside the volume expansion portion Bg including the box-shaped body 31 connected to the lower portion of the manifold Mi by a plurality of bolts 32. Downstream intake passage
At the downstream end of 16, on the left and right sides thereof, left and right communication ports 33l, which communicate with the resonance chambers Cr-l, Cr-r, respectively.
33r is opened. And the left and right communication ports 33l, 33r
Are arranged in the vicinity of the valve opening 24 and are arranged in parallel so as to face both sides of the valve opening 24.

When the valve body 27 is closed, the left and right branch resonance passages 22l and 22r are independently connected to the left and right resonance chambers Cr-l and Cr-r through the communication ports 33l and 33r, respectively. And forms two resonance supercharged intake systems.

When the valve body 27 is opened, the left and right resonance chambers Cr-
l, Cr-r is the valve port 24 and the left and right communication ports 33l, 33
A large volume inertial supercharging distribution chamber Ch shown by a two-dot chain line diagonal line in FIG.

On the upper walls of the left and right resonance chambers Cr-l, Cr-r, three left and right exhaust ports 34l ..., 34r ... Each having an oval shape are opened along the longitudinal direction thereof. The three exhaust ports 34l of the left resonance chamber Cr-1 are connected to the three cylinders 3r of the right cylinder block 1r located on the opposite side of the left resonance chamber Cr-1 via an intake manifold Mi described later (intake order). Are not continuous),
Similarly, three exhaust ports 34r of the right resonance chamber Cr-r
Are communicated with three cylinders 3l of the left cylinder block 1 located on the opposite side of the right resonance chamber Cr-r (intake order is not continuous) via an intake manifold Mi described later.

As shown in FIGS. 4 to 7, in the intake manifold Mi, the six first to sixth distribution pipes 35 _{1 to} 35 _{6 in} which the upstream side is curved upwardly and the downstream side is substantially linear are the downstream side intake passages. 16 and the left and right resonance chambers Cr-l, Cr-r are arranged side by side in a direction substantially orthogonal to the longitudinal direction and alternately intersect in opposite directions and extend left and right. Second, fourth
And sixth minutes pipe 35 _2, 35 ₄ and 35 upstream ends of ₆ extends on the opposite side of the resonance chamber Cr-l after passed through each communicating three exhaust ports 34l ... to the left resonance chamber Cr-l thereof The downstream end communicates with each of the three cylinders 3r ... of the right cylinder block 1r.
One of the first, third and fifth minute pipe 35 _1, 35 ₃ and 35 of the upstream end of the ₅ three right resonance chamber Cr-r exhaust port 34r
, Respectively, and then the resonance chamber Cr-r
To the three cylinders 3l ... Of the left cylinder block 1 respectively.

A cover 37 is fixed to the upper surface of the intake manifold Mi by a plurality of bolts 36, and the six first to sixth distribution pipes 35 _{1 to} 35 ₆
A tube length switching chamber Cc is formed between the curved upper outer wall and the outer wall. The first to sixth of the pipe 35 _{1-35 6} and pipe length switching chamber Cc tube length of the right and left of the butterfly type in the boundary portion between the switching valve 38l, 38r is provided. That is, the first to sixth distribution pipes 3
5 _{1-35 6} downstream end of the curved portion of, and the wall surface of the curved outward and valve port 39 ₁ to 39 ₆ as the opening of the distributor pipe 35 _{1-35 6} is opened, the left resonance chamber Cr-l with 3 distributing pipes 35 _2, 35 _4, 35 valve port 39 formed in the _{6 2,} 39 _4, 39 ₆ communicates with the lower surface right of the pipe length switching chamber Cc extending from, extending from the right resonance chamber Cr-r Three distribution pipes 35 ₁ , 3
5 _3, 35 ₅ valve port 39 ₁ formed in, 39 _3, 39 ₅ communicates with the lower surface left side of the pipe length switching chamber Cc. A pair of left and right valve shafts 40 rotatably instructed to penetrate both sides of the intake manifold Mi
l and 40r cross the center of each of the three valve openings 39 ₁ , 39 ₃ , 39 ₅ on the left side and the three valve openings 39 ₂ , 39 ₄ , 39 ₆ on the right side, and each valve opening 39 _{1 at} that position. the valve body 41 _{1-41 6} for opening and closing the ~ 39 ₆ are fixed with a screw 42. As is clear from FIG. 4, the valve bodies 41 ₁ to 4 ₁₆ are made of elliptical plate bodies and are fixed in a state where their short axes are aligned with the directions of the valve shafts 40l and 40r. The ends of both valve shafts 40l, 40r projecting from the intake manifold Mi are connected to an actuator 43, and pipe length switching valves 38l, 38
It is designed to open and close r, and for example, pipe length switching valves 38l, 38r are controlled to be closed in the medium speed range of the engine or lower,
The valve opening is controlled in the high speed rotation range.

As it is apparent from Figure 5, the valve port 39 ₁ to 39 the valve shaft passing through the center of the ₆ 40 l, 40r are located on schematic extension distributing pipes 35 ₁ to 35 ₆ curved outer wall, the valve body 41 _{1-41 6} is arranged to compensate for the distributor pipe 35 _{1-35 6} outer wall of which is cut away to form the valve port 39 ₁ to 39 ₆ in the closed position shown by solid lines. Thus, when the valve body 41 _{1-41 6} is closed, the cross-sectional area of the distributor pipe 35 _{1-35 6} is configured not to sudden change in the portion of the valve ports 39 ₁ to 39 _6. Also, the valve bodies 41 _{1 to 4 16}
There when in the open position shown by a chain line, downstream and pipe length switching chamber Cc forming the distributor pipe 35 _{1-35 6} schematically straight is formed so as to be connected via a straight path.

As shown in FIGS. 1 and 4, the first to sixth distribution pipes 35
Each of the upper wall of the _{1-35 6} downstream end of the fuel injection nozzle 44 ...
Is provided.

Next, the operation of the embodiment of the present invention will be described.

The two actuators 29, 43 are actuated and controlled according to the operating state of the engine. For example, in the low speed operating state, the left and right pipe length switching valves 38l, 38r are closed and controlled as shown by the solid line in FIG. The on-off valve 23 is controlled to be closed as shown by the solid line in FIG. Then, the communication of the left and right branch resonance passages 22l, 22r of the downstream side intake passage 16 is cut off, and the branch resonance passages 22l, 22r for each cylinder group as an intake system and the left and right resonance chambers Cr-l for each cylinder group are provided. Cr-r and left and right distribution pipes 35 ₁ , 3 for each cylinder group
_Two intake systems consisting of 5 ₂ , 35 ₃ , 35 ₄ , 35 ₅ , and 35 ₆ , that is, two resonances from each of the three cylinders 3l ..., 3r ... to the upstream of the intake passage Pi without intake interference. A supercharging system is configured, and the resonance supercharging system has a relatively long passage length, and its natural frequency is that of each intake valve 10 in the low speed rotation range of the engine.
The opening and closing cycle of ... Can be made substantially coincident with each other, the resonance supercharging effect can be effectively exhibited, and the volume efficiency in the low speed rotation range of the engine can be enhanced.

The above-mentioned pipe length changeover valve 38l, in the state in which 38r is closed controlled valve 41 _{1-41 6} distributor pipe to close the valve port 39 ₁ to 39 ₆
For constituting a part of the outer wall 35 _{1-35 6,}該分pipe 35 _1-3
No sudden change in cross-sectional area occurs at 5 ₆ . Therefore,
Attenuation of pressure waves is prevented, and a smooth flow of intake air is ensured, so that volumetric efficiency can be increased.

When the engine is in the medium speed operation state, the on-off valve 23 is controlled to open as shown by the chain line in Fig. 3, and the left and right resonance chambers Cr-l, Cr
-R communicates with each other to form a large volume inertial supercharging distribution chamber Ch indicated by a chain double-dashed line in FIG.
Are commonly communicated with the left and right cylinders 3l ... and 3r. Then, in this state, the two resonance supercharging systems are capsulated, the negative pressure wave generated in the engine intake stroke is reflected and inverted by the large-volume inertial supercharging distribution chamber Ch, and the positive pressure wave is generated in each cylinder 3l.
, 3r ... Inertial supercharging system is formed by propagating to the intake port 8 and the passage length of the negative pressure wave and the positive pressure wave is shortened. The volume efficiency in the medium speed operation range is increased in accordance with the opening / closing cycle of the intake valves.

When the engine reaches high speed operation, the pipe length switching valve 38l,
The valve opening of 38r is controlled as shown by the chain line in FIG.
The intermediate parts of the distribution pipes 35 ₁ , 35 ₃ , 35 ₅ connected to l are valve ports 39 ₁ , 3
9 _3, 39 ₅ communicates with the pipe length switching chamber Cc through the middle portion of the distribution pipe 35 _2, 35 _4, 35 ₆ to connect to the cylinder groups Cr via the valve port 39 _2, 39 _4, 39 ₆ It communicates with the pipe length switching chamber Cc. And the pipe length switching chamber Cc is a distribution pipe 35 _{1 to} 3
The inertial supercharging distribution chamber Ch is inserted through the upstream side of 5 ₆ to form an expanded inertial supercharging distribution chamber Ch '(see the chain double-dashed line in FIG. 5). Therefore, the expanded inertial supercharging distribution chamber Ch ′ and the left and right cylinder groups Cl and Cr are connected to the distribution pipe 3
5 _{1-35 6} is the shortest the valve ports 39 ₁ to 39 ₆ is connected via a downstream portion than in passage length of, and will be larger inertial supercharging system natural frequency is configured, the intake The pressure cycle can be matched with the opening / closing cycle of the intake valve 10 during high-speed operation of the engine to enhance the volumetric efficiency in the operating range.

At this time, as apparent from Figs. 1 and 5, the pipe length switching valves 38l, 3
Valve port 39 ₁ to 39 ₆ 8r is formed on the outer wall surface of the curved portion of the distributor pipe 35 _{1-35 6,} the valve element 41 _{1-41 6} And attached to the valve port 39 ₁ to 39 ₆ Pipe length switching valve chamber Cc and each cylinder 3l ..., 3
Since the valve opening operation is performed at a position parallel to the passage connecting r ..., The pipe length switching valve chamber Cc and each cylinder 3l ..., 3r ... Are connected through a substantially linear passage, and the valve elements 41 ₁ ... 41 ₆ does not become obstacle of the passage. Therefore, the propagation speed of the pressure wave in the high speed operation region is increased, and the volume efficiency in the operation region can be improved.

In the above embodiment, the pipe length switching chamber Cc in which the middle portion of the distribution pipes 35 _{1 to} 35 ₆ is short-circuited is such that the cylinder groups Cl and Cr whose intake strokes are not continuous communicate with each other to form an inertial supercharging system. The pipe length switching chamber Cc referred to in the present invention also includes a so-called resonance chamber for forming a resonance supercharging system.

In the above embodiment, the distributor pipe 35 _{1-35 6} and pipe length switching chamber Cc is communicated directly via the valve port 39 ₁ to 39 _6, the distribution pipe 35 _{1-35 6} and pipe length switching chamber Cc short branch pipe is interposed in the branch pipe and the distributor pipe 35 _{1-35 6} connecting portion in the pipe length switching valve 38l, may be attached to 38r between.

C. Effect of the Invention As described above, according to the first feature of the present invention, a plurality of distribution pipes that are separately connected to the left and right cylinder groups are curved in an inverted U shape, and a pipe length switching chamber is provided above the distribution pipes. By providing V
It is possible to effectively utilize the space of the narrow V space of the multi-cylinder internal combustion engine. Moreover, the downstream side of the distribution pipe is linearly connected to the left and right cylinder groups, and an opening communicating with the pipe length switching chamber is formed on the outer wall surface of the curved portion of the distribution pipe to form the pipe length switching chamber and the left and right cylinders. By communicating the cylinder groups through the straight passages, the propagation speed of the pressure wave is increased, and higher volume efficiency in the high speed operation range is secured.

Further, according to the second feature of the present invention, the valve body that opens and closes the opening is a butterfly type, and at its open position, the valve body rotates to a position parallel to the passage connecting the pipe length switching chamber and each cylinder. In the high speed operation range, the pressure wave is smoothly propagated between the pipe length switching chamber and each cylinder, and higher volume efficiency is secured.

[Brief description of drawings]

1 to 7 show a first embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a V type 6 cylinder internal combustion engine equipped with the device of the present invention, and FIG. Fig. 3 is an enlarged partial plan view taken along line III-III in Fig. 1, Fig. 4 is an enlarged partial plan view taken along line IV-IV in Fig. 1, and Fig. 5 is taken along line VV in Fig. 4. 6 is a sectional view taken along line VI-VI in FIG. 5, and FIG. 7 is a sectional view taken along line VII-VII in FIG. C ... V space, Cc ... tube length switching chamber, Cl, Cr ... cylinder group 35 _{1 to} 35 ₆ ... Distribution pipe, 38l, 38r ... pipe length switching valve, 39 _{1 to} 39
₆ …… Valve mouth (opening), 41 _{1 to} 41 ₆ …… Valve

Claims (2)

[Scope of utility model registration request] 1. A pipe length switching valve downstream end left, right cylinder group and (Cl, Cr) a plurality of distribution pipes connected to each other in (35 ₁ to 35 ₆₎ are opened and closed controlled in accordance with the operating condition of the engine (38l, 38r) intermediate portion of the intake device for a V-type multi-cylinder internal combustion engine and a pipe length switching chamber (Cc) is disposed in the V-space (C) which communicates said distribution pipe through a (35 ₁ to 35 ₆₎ straight in, together with the distribution pipe (35 ₁ to 35 ₆₎ is curved in an inverted U-shape providing the tube length switching chamber thereon (Cc), the downstream side of the distribution pipe (35 ₁ to 35 ₆₎ to the left, right cylinder group (Cl, Cr) connected to, and the distribution pipe (35 ₁ to 35 ₆₎ opening (39 ₁ communicating with the duct length switching chamber (Cc) on the outside wall surface of the curved portion of the ~ 39 ₆ ) is formed to connect the left and right cylinder groups (Cl, Cr) of the pipe length switching chamber (Cc) via a linear passage, and a V-type multi-cylinder internal combustion engine. Intake device. Wherein said opening butterfly type valve body (39 ₁ to 39 ₆₎ (41 ₁ to 41 ₆₎ pipe length changeover valve having (38l, 38r) attached to, opening (39 ₁ to 39 ₆₎ and left, right cylinder group to open the duct length switching chamber (Cc) (Cl, Cr) when connecting the said valve body (41 ₁ to 41 ₆₎ a pipe length switching chamber (Cc) and the left, right cylinder group The intake system for a V-type multi-cylinder internal combustion engine according to claim 1, wherein the intake system is rotated to a position parallel to a passage connecting (Cl, Cr).