Crankcase compression type two-cycle engine

The present invention provides a crankcase compression type two-cycle engine which has a comparatively simple construction, is capable of operating at a low fuel consumption and discharges an exhaust gas having a comparatively low hydrocarbon concentration. The engine comprises a crankcase, a piston, a cylinder joined to the crankcase and provided in its lower part with an exhaust port which is opened and closed by the piston, a cylinder head attached to the upper end of the cylinder, and forming a combustion chamber together with the cylinder and the piston. A poppet scavenging valve is provided in the upper part of the cylinder so as to be opened to the combustion chamber side. A diaphragm actuator operates the poppet scavenging valve using the pressure within the crankcase. The diaphragm actuator is provided with a diaphragm that receives the pressure within the crankcase on one side thereof and receives the pressure of a spring on the other side thereof. Further, a passage for introducing the pressure within the crankcase into the diaphragm actuator is connected to a scavenging passage. A fuel supply system may be connected to the scavenging passage to supply the fuel into the scavenging passage.

BACKGROUND OF THE INVENTION 
1. Field of the Invention: 
The present invention relates to a small-capacity crankcase compression 
type two-cycle gasoline engine. 
2. Description of the Related Art: 
Referring to FIG. 8 showing a conventional small-capacity crankcase 
compression type two-cycle gasoline engine by way of example, there are 
shown a cylinder 1' provided with a scavenging hole 6', a piston 2', a 
crankshaft 3', a connecting rod 4', a crankcase 5' having a crank chamber, 
a cylinder head 8', a combustion chamber 9', an ignition plug 12', and a 
scavenging passage 61' connecting the crank chamber of the crankcase 5' to 
the scavenging hole 6'. In FIG. 8, the exhaust port of the cylinder 1' is 
not shown. The piston 2' is forced to move downward by the pressure of a 
combustion gas 13' produced by the combustion of a fuel-air mixture within 
the combustion chamber 9' to rotate the crankshaft 3' through the 
connecting rod 4'. As the piston 2' moves downward, the exhaust hole, not 
shown, opens gradually to allow the combustion gas to flow out of the 
combustion chamber 9' and, at the same time, a fuel-air mixture previously 
taken into the crankcase 5' through an intake hole, not shown, is 
compressed within the crankcase 5', and it is introduced into the 
combustion chamber 9' through the scavenging hole 6' to scavenge the 
combustion gas. This scavenging system is called a Schnule type scavenging 
system and its gas exchange pattern is shown in FIG. 9. 
In the engine of this type, both of the scavenging hole and the exhaust 
port are provided at the side of the cylinder and are adjacent to each 
other. Accordingly, the fresh air 14' tends to escape directly from the 
scavenging hole to the exhaust port. Especially in the engine in which 
fuel is premixed with the fresh air by a carburetor, fuel content is 
included in the escaping fresh air as above, and hence, the fuel 
consumption rate is deteriorated and the hydrocarbon concentration in the 
exhaust gas becomes high. However, the Schnule type engine has advantages 
in that an exhaust valve and a driving mechanism therefor, of it such as a 
cam or a rocker arm, are unnecessary and, therefore, the construction is 
simple. 
In order to solve the problem of the escape of part of the fuel-air mixture 
in the Schnule type scavenging system, a uniflow scavenging type two-cycle 
engine is proposed. In FIG. 10, one example of this uniflow scavenging 
type two-cycle engine is shown. 
In FIG. 10, an exhaust valve 11' provided in a cylinder head 8' is driven 
to open and close an exhaust port 7' by a valve operating mechanism 
comprising a cam 36' mounted on a crankshaft 3', a valve tappet 13', a 
push rod 14' and a rocker arm 15'. The fuel-air mixture precharged in a 
crankcase 5' flows through a scavenging hole 6 into a combustion chamber 
9' to scavenge the combustion gas remaining within the combustion chamber 
9' so that the combustion gas 13' will be discharged through the exhaust 
port 7'. The flow pattern of the gas exchange in the uniflow scavenging 
type two-cycle engine is illustrated in FIG. 11. 
Although the Schnule scavenging type two-cycle engine shown in FIG. 8 has a 
simple construction, the Schnule scavenging type two-cycle engine, 
especially in a case where the fuel is premixed with the fresh air by the 
carburetor, is disadvantageous in that its fuel consumption rate is high 
and its exhaust gas has a high hydrocarbon concentration because the 
cylinder is scavenged with the fuel-air mixture and a part of the fuel-air 
mixture escapes together with the combustion gas through the exhaust port. 
Hereinafter, the escape of a part of the fuel-air mixture together with 
the combustion gas is called "blowby" in this specification. 
The uniflow scavenging type two-cycle engine shown in FIG. 10 proposed to 
suppress the direct discharge of the fuel-air mixture needs the valve 
operating mechanism and hence has a complex construction. Although it is 
most effective in reducing wasteful fuel consumption attributable to the 
blowby of the fuel-air mixture to inject the fuel directly into the 
combustion chamber 9' after the exhaust port has been closed, the fuel 
must be injected at a high pressure into the combustion chamber 9' to 
produce a fuel-air mixture immediately within the combustion chamber 9', 
which requires a cam, an injection pump and the associated parts for 
high-pressure fuel injection, and the fuel injection mechanism makes the 
construction of the uniflow scavenging type two-cycle engine more complex. 
SUMMARY OF THE INVENTION 
Accordingly it is an object of the present invention to provide an improved 
two-cycle engine incorporating the simple, lightweight construction of the 
Schnule scavenging type two-cycle engine, and capable of preventing the 
blowby of the fuel-air mixture, of operating at an improved fuel 
consumption and of discharging an improved exhaust gas having a reduced 
hydrocarbon concentration. 
With the foregoing object in view, the present invention provides a 
crankcase compression type two-cycle engine characterized in that: 
(1) an exhaust port is formed in the lower part of a cylinder so as to be 
closed and opened when a piston moves past the bottom dead point, a poppet 
scavenging valve is provided in the upper part of the cylinder to be 
opened to the combustion chamber side and also a valve operating means for 
opening the scavenging valve using the pressure of the gas compressed in 
the crankcase in a state where the piston is moving in the vicinity of the 
bottom dead center; 
(2) the valve operating means is a diaphragm actuator provided with a 
diaphragm that receives the pressure of a spring on one side thereof and 
the pressure of the gas compressed in the crankcase on the other side 
thereof, and capable of operating by the difference between the pressure 
of the spring and the pressure of the gas compressed in the crankcase; 
(3) a passage through which the pressure of the gas compressed in the 
crankcase is applied to the valve operating means is connected to a 
scavenging passage; 
(4) an exhaust port and a scavenging hole are formed in the lower part of a 
cylinder so as to be opened and closed by a piston as the piston moves 
toward and past the bottom dead center, a combustion chamber formed in the 
top part of the cylinder and interior of the crankcase are connected by a 
scavenging passage, at least one scavenging valve is disposed in a top 
part of the cylinder, and a fuel supply system is connected to the 
scavenging passage at a position upstream of the scavenging valve to 
supply the fuel into the scavenging passage; 
(5), an intake device which takes only air into the crankcase is provided; 
(6), the scavenging valve is of an electromagnetic type with a solenoid 
which is energized by a crank angle sensor and operated by an 
electromagnetic force thereof; 
(7), the scavenging valve is of a diaphragm actuator type operated by a 
diaphragm on which pressure of the gas compressed in the crankcase and 
force of a spring act; 
(8), the fuel supply system is of a carburetor type having an intake 
passage connected through a reed valve to the scavenging passage; 
(9), the fuel supply system is of a fuel injection type having a fuel 
injection valve disposed in the scavenging passage and immediately 
upstream of the scavenging valve and a fuel pump for supplying the fuel to 
the fuel injection valve under pressure; 
(10), the scavenging passage connected to the top part of the cylinder is 
provided with a throttling means; and 
(11), the crankcase compression type two-cycle engine is provided with a 
plurality of scavenging valves. 
In the crankcase compression type two-cycle engine characterized by (1) to 
(3), the exhaust port of the cylinder starts opening as the piston moves 
downward in the final stage of the expansion stroke to discharge the 
combustion gas through the exhaust port, so that the pressure within the 
cylinder decreases, while the fuel-air mixture charged in the crankcase is 
compressed by the downward movement of the piston. The fuel-air mixture 
flows through the scavenging passage toward the scavenging valve, the 
pressure of the fuel-air mixture acts on the valve operating means, such 
as the diaphragm actuator, to open the scavenging valve, the fuel-air 
mixture flows into the combustion chamber and, consequently, the pressure 
of the gas within the crankcase decreases. Then, as the piston moves 
upward, the exhaust port is closed, the pressure of the fuel-air mixture 
increases gradually as the same is compressed by the rising piston and the 
scavenging valve is closed. 
In the crankcase compression type two-cycle engine characterized by (4), 
(5) and (7), the fuel or a fuel-air mixture is mixed in the air flowing 
from the crankcase through the scavenging passage at a position 
immediately upstream of the scavenging valve by the fuel supply system, 
such as a carburetor, and the scavenging valve is opened by the diaphragm 
actuator to allow the fuel-air mixture to flow into the combustion 
chamber. 
In the crankcase compression type two-cycle engine characterized by (6), 
the solenoid is energized when the crank angle sensor provides a valve 
opening and closing signal upon the detection of a specified crank angle 
to open and close the scavenging valve by the electromagnetic force 
generated by the solenoid (or the electromagnetic force and the pressure 
of a spring). 
In the crankcase compression type two-cycle engine characterized by (8), 
the fuel-air mixture made by the carburetor flows through the reed valve 
into the scavenging passage and flows into the combustion chamber when the 
scavenging valve is opened. 
In the crankcase compression type two-cycle engine characterized by (9) to 
(11), a fuel-air mixture is produced by injecting the fuel by the fuel 
injection valve into the compressed air flowing through the scavenging 
passage, and the fuel-air mixture flows through one or a plurality of 
scavenging valves into the combustion chamber for burning. The throttling 
means adjusts the flow passage area of the scavenging passage.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, a crankcase compression type two-cycle engine 
(hereinafter referred to simply as "engine") in a first embodiment 
according to the present invention comprises, as principal components, a 
cylinder 1, a piston 2, a crankshaft 3, a connecting rod 4, a crankcase 5, 
a cylinder head 8, an ignition plug 12 (spark plug), a scavenging valve 
21, i.e., a poppet valve, provided on the cylinder head 8 to be pressed 
axially into the cylinder 1 to open a scavenging port 22 formed in the 
cylinder head 8, and a diaphragm actuator 100 for operating the scavenging 
valve 21. A combustion chamber 9 is defined by the cylinder 1, the piston 
2 and the cylinder head 8. The diaphragm actuator 100 has a diaphragm 31 
partitioning a cavity formed in the cylinder head 8 so as to receive the 
upper end of the scavenging valve 21 into a valve chamber 32 and a 
pressure chamber 33. The scavenging valve 21 is biased toward the closed 
position by a valve spring 29 retained by a valve spring retainer 28 
fastened to the stem of the scavenging valve 21. 
The cylinder 1 is provided with a scavenging hole 24 and an exhaust port 40 
in its lower part, and a scavenging passage 23 having a lower end opening 
into the crankcase 5 and an upper end connected to the pressure chamber 33 
and a scavenging port 22. The stem of the scavenging valve 21 is supported 
for axial movement in a valve guide 27 attached to the cylinder head 8. 
The valve chamber 32 communicates with the atmosphere by means of a hole 
35. The scavenging passage 23 is branched in the cylinder head 8 into an 
operating air passage 23a connected to the pressure chamber 33, and a 
branch passage connected to the scavenging port 22 opened and closed by 
the scavenging valve 21. 
In operation, upon the arrival of the piston 2 at a specified position 
during the expansion stroke, the exhaust port 40 is opened to discharge 
the combustion gas through the exhaust port 40. As the piston 2 moves 
downward, the fuel-air mixture previously supplied through an intake 
passage, not shown, into the crankcase 5 is compressed. The pressure of 
the compressed fuel-air mixture prevails in the scavenging passage 23, the 
scavenging port 22, the operating air passage 23a and the pressure chamber 
33. As the piston 2 moves further downward, the opening of the exhaust 
port 40 increases, the internal pressure of the combustion chamber 9 
decreases and the pressure of the fuel-air mixture compressed in the 
crankcase 5 increases. Eventually, the pressure of the fuel-air mixture 
prevailing in the pressure chamber 33 and acting on the diaphragm 31 
exceeds the resilience of the valve spring 29 and, consequently, the 
scavenging valve 21 is moved into the combustion chamber 9 to open the 
scavenging port 22 into the combustion chamber 9, so that the fuel-air 
mixture flows through the scavenging valve 21 into the combustion chamber 
9. Then, the fuel-air mixture flows downward from the upper part of the 
interior of the cylinder 1 near the scavenging valve 21 toward the lower 
part of the interior of the cylinder 1 near the exhaust port 40 to 
scavenge the cylinder 1. As the piston 2 moves upward for the compression 
stroke, the crankcase 5 is evacuated, so that the intake passage, not 
shown, formed in the lower part of the cylinder 1 is opened to suck the 
fuel-air mixture made by a carburetor, not shown, into the crankcase 5. 
As shown typically in FIG. 2, the flow of the fuel-air mixture and the 
combustion gas within the cylinder 1 is of a simple uniflow, which is 
similar to that of the fuel-air mixture and the combustion gas in the 
cylinder of the uniflow scavenging type two-cycle engine of FIG. 10, 
except that the direction of flow of the fuel-air mixture and the 
combustion gas is reverse to that of flow of the fuel-air mixture and the 
combustion gas in the cylinder of the uniflow scavenging type two-cycle 
engine of FIG. 10. Only a very small quantity of the fuel content blows by 
through the exhaust port 40. 
A crankcase compression type two-cycle engine in a second embodiment 
according to the present invention will be described hereinafter with 
reference to FIGS. 3 and 4(A) to 4(D). 
Shown in FIG. 3 are a cylinder 1, a piston 2, a crank shaft 3, a connecting 
rod 4, a crankcase 5, a cylinder head 8, a combustion chamber 9 and an 
ignition plug 12. 
The cylinder is provided with an exhaust port 40 and a lower scavenging 
hole 6 in its lower part. The scavenging hole 6 has an area smaller than 
that of the scavenging hole of an equivalent conventional two-cycle 
engine. The crankcase 5 is provided with an intake passage 531 provided 
with a reed valve 53b. Fresh air is sucked through an air cleaner 51b and 
the intake passage 531 into the crankcase 5. A poppet scavenging valve 21 
is supported for axial movement on the cylinder head 8 and is biased 
toward the closed position with a valve spring 29. The scavenging valve 21 
is pushed into the combustion chamber 9 to be opened. The scavenging 
passage 23 has a lower end connected to the crankcase 5 and an upper end 
connected to the upper scavenging port 22. The scavenging valve 21 is 
operated by a solenoid 41 which is driven by an electrical solenoid 
circuit 42. A crank angle sensor 43 gives a crank angle signal indicating 
a specified crank angle of the engine to the solenoid circuit 42. The 
solenoid circuit 42 sends signals to the solenoid 41 so as to open the 
scavenging valve 21 with a slight delay after the scavenging hole 6 has 
been opened and to close the scavenging valve 21 substantially 
simultaneously with the closing of the exhaust port 40. A fuel supply 
system 200 is disposed near the upper end of the scavenging passage 23. 
The fuel supply system 200 comprises a reed valve 53a, an air cleaner 51a, 
a throttle valve 55a and a carburetor 52. A fuel-air mixture made by the 
carburetor 52 flows through the reed valve 53a into the upper scavenging 
port 22. The throttle valve 55a of the fuel supply system 200 and a 
throttle valve 55b disposed in the fresh air passage 531 are interlocked 
mechanically and the respective openings of the throttle valves 55a and 
55b are regulated according to the load on the engine. 
The operation of the engine in the second embodiment will be described 
hereinafter with reference to FIGS. 3 and 4(A) to 4(D). In the expansion 
stroke, as the piston 2 moves downward turning the crankshaft 3 through 
the connecting rod 4, first the exhaust port 40 is opened and the 
high-pressure combustion gas G flows out of the combustion chamber 9 into 
the muffler as shown in FIG. 4(A). As the piston moves further downward, 
the scavenging hole 6 is opened to allow compressed fresh air H compressed 
in the crankcase 5 by the piston 2 moving downward to flow through the 
lower scavenging hole 6 into the combustion chamber 9 to scavenge the 
combustion chamber 9 as shown in FIG. 4(B). Then the solenoid 41 opens the 
scavenging valve 21 with a slight delay after the lower scavenging hole 6 
has been opened. Since the exhaust port 40 is open and the pressure within 
the combustion chamber 9 is comparatively low, the fuel-air mixture J, 
made by the carburetor 52 of the fuel supply system 200 connected to the 
inlet of the upper scavenging port 22 and filled in the scavenging port 22 
and the scavenging passage 23, is urged to flow through the scavenging 
valve 21 into the combustion chamber 9. 
The fresh air H supplied through the scavenging hole 6 at the lower part of 
the cylinder into the combustion chamber 9 collides with the flow of the 
fuel-air mixture J supplied through the scavenging valve 21 into the 
combustion chamber 9 as shown in FIG. 4(C) to suppress the blowby of the 
fuel-air mixture J through the discharge port 40. 
In the compression stroke where the piston 2 moves upward, the scavenging 
hole 6, the exhaust port 40 and the scavenging valve 21 are closed, the 
fuel-air mixture J is compressed in the cylinder 1, and the pressure 
within the crankcase 5, the scavenging port 22 and the scavenging passage 
23 decreases. Upon the drop of this pressure to a fixed pressure, the reed 
valve 53a of the fuel supply system 200 and the reed valve 53b disposed in 
the intake passage 531 open substantially simultaneously to supply the 
fuel-air mixture made by the carburetor 52 into the scavenging passage 23 
and the scavenging port 22 and to suck fresh air through the reed valve 
53b into the crankcase 5. Consequently, the scavenging port 22 and the 
upper part of the scavenging passage 23 are filled up with the new 
fuel-air mixture K as shown in FIG. 4(D). 
In this embodiment, lubricating oil is injected into a space near the 
throttle valve 55b within the intake passage 531 by a known separate 
oiling system to blow the lubricating oil into the crankcase 5. 
A crankcase compression type two-cycle engine in a third embodiment 
according to the present invention will be described hereinafter with 
reference to FIG. 5. The engine in the third embodiment is substantially 
the same in construction as the engine in the second embodiment, except 
that the engine in the third embodiment employs a fuel supply system 
different from the fuel supply system 200 of the second embodiment 
provided with the carburetor 52. Therefore parts like or corresponding to 
those shown in FIG. 3 are denoted by the same reference characters and the 
description thereof will be omitted. 
Referring to FIG. 5, the engine is provided with a fuel supply system 
comprising a fuel pump 61 and a fuel injection valve 63 connected to the 
fuel pump 61 by a fuel supply pipe 64 and disposed so as to inject the 
fuel into the scavenging port 22. The fuel injection rate and the fuel 
injection time of the fuel injection valve 63 are controlled in 
synchronism with the operation of the scavenging valve 21 by the circuit 
42 for driving the solenoid 41 for operating the scavenging valve 21. The 
scavenging passage 23 is provided with a throttle valve 70 for regulating 
the flow passage area of the scavenging passage 23. 
In the engine of the third embodiment, the fresh air compressed in the 
crankcase 5 by the piston 2 moving downward flows through the scavenging 
passage 23 into the scavenging port 22, and then the fuel injection valve 
63 injects the fuel into the fresh air with an appropriate timing to 
produce a fuel-air mixture. The fuel-air mixture is supplied into the 
combustion chamber 9 when the scavenging valve 21 is opened. The flow 
ratio between the fuel-air mixture that flows into the cylinder 1 when the 
scavenging valve 21 is opened and the fresh air that flows through the 
scavenging hole 6 into the cylinder 1 is regulated by controlling the 
opening of the throttle valve 70 provided in the scavenging passage 23. 
A crankcase compression type two-cycle engine in a fourth embodiment 
according to the present invention will be described hereinafter with 
reference to FIG. 6. As shown in FIG. 6, the engine is provided with a 
scavenging valve 21 driven, similarly to the scavenging valve 21 of the 
first embodiment, by the pressure of the compressed air prevailing within 
a scavenging passage 23 from a crankcase 5, and is provided, similarly to 
the engine in the second embodiment, with a fuel supply system 200 
provided with a carburetor 52 and disposed near a scavenging port 22. The 
upper part of the scavenging passage 23 is branched into an operating air 
passage 23a and the scavenging port 2. The operating air passage 23a is 
connected to a pressure chamber 33 of a diaphragm actuator 100 to apply 
the pressure of the compressed air within the crankcase 5 to one side of 
the diaphragm 31 of the diaphragm actuator 100. The scavenging valve 21 is 
supported on a cylinder head 8 at the outlet of the scavenging port 22. 
When a reed valve 53a is opened, the fuel-air mixture made by the 
carburetor 52 of the fuel supply system 200 flows into the scavenging port 
22. 
As the piston 2 moves downward, the internal pressure of the crankcase 5 
increases and the pressure of the compressed air filling up the crankcase 
5, the scavenging passage 23, the operating air passage 23a and the 
pressure chamber 33 acts on one side of the diaphragm 31. After an exhaust 
port 40 has been opened, the pressure within the combustion chamber 9 
decreases and, when the pressure within the pressure chamber 33 exceeds 
the sum of the resilience of a valve spring 29 and the pressure within the 
combustion chamber 9 acting on the scavenging valve 21, the scavenging 
valve 21 is opened to allow the fuel-air mixture within the scavenging 
port 22 to flow into the combustion chamber 9. 
The gas flows past the scavenging valve 21 in an annular jet through an 
annular passage having a shape dependent on the circumferential length and 
the lift of the scavenging valve 21. When the fuel-air mixture flows in an 
annular jet, a negative pressure is produced in the central region of the 
annular jet and part of the combustion gas is liable to stay on in the 
central region of the annular jet of the fuel-air mixture. Furthermore, 
since the outer part of the annular jet tends to adhere to the inner 
circumference of the cylinder, the gas tends to remain below the 
scavenging valve 21. In a cylinder provided with a plurality of scavenging 
valves 21, jets of fuel-air mixture tend to flow in the central region of 
the interior of the cylinder, and the space where the jets become weak is 
reduced and the residual combustion gas is reduced. 
The relation between the diameter D of the valve head, the sectional area S 
of the valve head and the circumferential length L of the valve head are 
expressed by: 
EQU S=.pi.D.sup.2 /4 (1) 
EQU L=.pi.D (2) 
EQU S=.pi.L2/4.pi. (3) 
Therefore, the sectional area S is directly proportional to L.sup.2. 
Since the relation between the sectional area Sj of the jet and the lift h 
of the scavenging valve 21 is expressed by: 
EQU Sj=L.multidot.h (4) 
the sectional area Sj is directly proportional to L. Accordingly, if a 
plurality of scavenging valves is used and the sum of the sectional areas 
of the plurality of scavenging valves is equal to the sectional area S of 
a single scavenging valve, the sum of the sectional areas of the jets 
flowing past the plurality of scavenging valves is greater than the 
sectional area of the jet flowing past the single scavenging valve. 
Accordingly, it is advantageous in preventing the deterioration of engine 
performance due to intake pressure loss and the like to use a plurality of 
scavenging valves having a smaller diameter. 
With this advantage of using a plurality of scavenging valves in view, a 
crankcase compression type two-cycle engine in a fifth embodiment 
according to the present invention shown in FIG. 7 is provided with two 
scavenging valve arrangement each having a scavenging valve 21 and a 
diaphragm actuator 100 which are similar in construction to the scavenging 
valve 21 and the diaphragm actuator 100 employed in the fourth embodiment. 
Excepting the number and arrangement of the scavenging valves 21 and the 
diaphragm actuators 100, the engine in the fifth embodiment is 
substantially the same in construction as those in the first and fourth 
embodiments. 
As is apparent from the foregoing description, the crankcase compression 
type two-cycle engine of the present invention has a construction 
equivalent to a combination of the construction of the Schnule scavenging 
type two-cycle engine and a comparatively simple mechanism, does not need 
such a complex valve operating mechanism as that employed in the uniflow 
scavenging type two-cycle engine, and is capable of effectively 
suppressing, similarly to the uniflow scavenging type two-cycle engine, 
the blowby of the fuel-air mixture. Accordingly, the crankcase compression 
type two-cycle engine of the present invention operates with low fuel 
consumption at a high efficiency and discharges an exhaust gas having a 
comparatively small hydrocarbon concentration. 
While there has been described preferred embodiments of the invention, 
obviously modifications and variations are possible in the light of the 
above teachings. It is therefore to be understood that within the scope of 
the appended claims, the invention may be practiced other than as 
specifically described herein.