Knock detection method and knock detection device
阅读说明:本技术 爆震检测方法以及爆震检测装置 (Knock detection method and knock detection device ) 是由 柚木晃广 竹本大育 于 2017-10-27 设计创作,主要内容包括:本发明提供一种爆震检测方法以及爆震检测装置。爆震检测方法具有:缸内压获取步骤,其在多个曲柄角中获取内燃机的气缸的缸内压力;生热率运算步骤,其对多个曲柄角的气缸的生热率分别进行运算;缸内压最大曲柄角获取步骤,其获取缸内压最大曲柄角;爆震判定曲柄角区域确定步骤,其确定作为在比缸内压最大曲柄角只小第一值的小侧曲柄角与比缸内压最大曲柄角只大第二值的大侧曲柄角之间的区域的爆震判定曲柄角区域;生热率微分步骤,其算出爆震判定曲柄角区域的生热率的微分值;第一爆震判定步骤,其基于在生热率微分步骤中算出的生热率的微分值,进行爆震判定。(The invention provides a knock detection method and a knock detection apparatus. The knock detection method includes: a cylinder pressure acquisition step of acquiring a cylinder pressure of a cylinder of the internal combustion engine in a plurality of crank angles; a heat generation rate calculation step of calculating heat generation rates of the cylinders at the plurality of crank angles, respectively; a cylinder internal pressure maximum crank angle acquisition step of acquiring a cylinder internal pressure maximum crank angle; a knocking determination crank angle region determining step of determining a knocking determination crank angle region as a region between a small side crank angle smaller than the in-cylinder pressure maximum crank angle by only a first value and a large side crank angle larger than the in-cylinder pressure maximum crank angle by only a second value; a heat generation rate differentiation step of calculating a differential value of a heat generation rate in a knock determination crank angle region; a first knock determination step of performing knock determination based on the differential value of the heat generation rate calculated in the heat generation rate differential step.)
1. A knock detection method for detecting knocking of an internal combustion engine, characterized by comprising:
an in-cylinder pressure acquisition step of acquiring in-cylinder pressures of cylinders included in the internal combustion engine at a plurality of crank angles;
a heat generation rate calculation step of calculating heat generation rates of the cylinders at a plurality of crank angles, respectively;
an in-cylinder pressure maximum crank angle acquisition step of acquiring an in-cylinder pressure maximum crank angle at which an in-cylinder pressure of the cylinder of the internal combustion engine is maximum;
a knocking determination crank angle region determining step of determining a knocking determination crank angle region as a region between a small side crank angle smaller than the in-cylinder pressure maximum crank angle by a first value and a large side crank angle larger than the in-cylinder pressure maximum crank angle by a second value;
a heat generation rate differentiation step of calculating a differential value of the heat generation rate in the knock determination crank angle region;
a first knock determination step of performing knock determination based on the differential value of the heat generation rate calculated in the heat generation rate differential step.
2. The knock detection method according to claim 1,
the first value and the second value are respectively 3 degrees to 7 degrees.
3. The knock detection method according to claim 1 or 2,
the first knock determination step acquires a maximum differential heat generation rate at which a differential value of the heat generation rate calculated in the heat generation rate differential step is a maximum value, and determines that knocking is present when the maximum differential heat generation rate is larger than a first knock determination threshold value.
4. The knock detection method according to claim 3,
further, there is a knock intensity determination step of determining a magnitude of knock intensity of the knock in a case where it is determined in the first knock determination step that the knock exists,
the knock intensity determination step includes:
a reference differential heat generation rate acquisition step of acquiring a reference differential heat generation rate in which a differential value of the heat generation rate is a maximum value, which is a reference crank angle region that is a region between a crank angle smaller by a third value than the small crank angle and the small crank angle;
a knock intensity determination step of determining that the knock intensity is strong when the magnitude of the maximum differential heat generation rate with respect to the reference differential heat generation rate is larger than a knock intensity determination threshold, and determining that the knock intensity is weak when the magnitude of the maximum differential heat generation rate with respect to the reference differential heat generation rate is equal to or smaller than the knock intensity determination threshold.
5. The knock detection method according to any one of claims 1 to 4,
further, the method includes a second knock determination step of determining that the knock having a strong knock intensity has been detected when a maximum heat generation rate of the heat generation rates is larger than a second knock determination threshold value.
6. The knock detection method according to any one of claims 1 to 5,
the heat generation rate calculation step calculates the heat generation rate for each of the plurality of crank angles using the cylinder pressure acquired in the cylinder pressure acquisition step.
7. A knocking detection device for detecting knocking of an internal combustion engine, the knocking detection device including a cylinder pressure sensor capable of detecting a cylinder pressure of a cylinder of the internal combustion engine and a crank angle sensor capable of detecting a crank angle of the internal combustion engine, the knocking detection device comprising:
a cylinder pressure acquisition unit that acquires the cylinder pressure detected by the cylinder pressure sensor at a plurality of crank angles;
a heat generation rate calculation unit that calculates heat generation rates of the cylinders at the plurality of crank angles, respectively;
a maximum-cylinder-pressure crank angle acquiring unit that acquires a maximum cylinder-pressure crank angle at which a cylinder pressure of the cylinder of the internal combustion engine is maximum;
a knock determination crank angle region determination portion that determines a knock determination crank angle region that is a region between a small side crank angle smaller than the maximum in-cylinder pressure by a first value and a large side crank angle larger than the maximum in-cylinder pressure by a second value;
a heat generation rate differentiation unit that calculates a differentiation value of the heat generation rate in the knock determination crank angle region;
and a first knock determination unit that performs knock determination based on the differential value of the heat generation rate calculated by the heat generation rate differential unit.
8. The knock detection device according to claim 7,
the first value and the second value are respectively 3 degrees to 7 degrees.
9. The knock detection device according to claim 7 or 8,
the first knock determination unit acquires a maximum differential heat generation rate at which a differential value of the heat generation rate calculated by the heat generation rate differential unit is a maximum value, and determines that knocking is present when the maximum differential heat generation rate is greater than a first knock determination threshold value.
10. The knock detection device according to claim 9,
further, the knock determination unit determines a level of knock intensity of the knock when the first knock determination unit determines that the knock is present,
the knock intensity determination unit includes:
a reference differential heat generation rate acquisition unit that acquires a reference differential heat generation rate in which a differential value of the heat generation rate is a maximum value in a reference crank angle region that is a region between a crank angle smaller by a third value than the small crank angle and the small crank angle;
and a knock intensity determination unit that determines that the knock intensity is strong when the magnitude of the maximum differential heat generation rate with respect to the reference differential heat generation rate is larger than a knock intensity determination threshold, and determines that the knock intensity is weak when the magnitude of the maximum differential heat generation rate with respect to the reference differential heat generation rate is equal to or smaller than the knock intensity determination threshold.
11. The knocking detection device according to any one of claims 7 to 10,
the knock determination unit further includes a second knock determination unit configured to determine that the knock having a strong knock intensity is detected when a maximum heat generation rate of the heat generation rates is larger than a second knock determination threshold value.
12. The knocking detection device according to any one of claims 7 to 11,
the heat generation rate calculation unit calculates the heat generation rate for each of the plurality of crank angles using the in-cylinder pressure acquired by the in-cylinder pressure acquisition unit.
Technical Field
The present invention relates to a knock detection method and a knock detection device for an internal combustion engine.
Background
Generally, the efficiency of an internal combustion engine such as a gas engine or a gasoline engine is higher as the ignition timing in each combustion cycle is earlier. On the other hand, the earlier the ignition timing, the higher the possibility of occurrence of knocking, which is an abnormal combustion phenomenon in which the exhaust gas unburned in the cylinder self-ignites (natural ignition). Further, the shock wave generated by the spontaneous combustion breaks a thermal boundary layer formed on the inner wall surface of the cylinder, thereby excessively raising the surface temperature of the inner wall surface of the cylinder, and causing damage to the internal combustion engine such as melting and damaging engine accessories such as a cylinder block. Therefore, detection of knocking is very important in order to avoid damage to the internal combustion engine due to knocking while operating the internal combustion engine as efficiently as possible. Especially, only strong knocking may cause damage to the internal combustion engine.
For example,
On the other hand,
Disclosure of Invention
Technical problem to be solved by the invention
As described in
On the other hand, in
The present invention has been made in view of the above problems, and an object of at least one embodiment of the present invention is to provide a knock detection method capable of more easily and accurately determining knocking based on a heat generation rate in a cylinder of an internal combustion engine.
Technical solution for solving technical problem
(1) A knock detection method of at least one embodiment of the present invention is a knock detection method for detecting knocking of an internal combustion engine, having:
an in-cylinder pressure acquisition step of acquiring an in-cylinder pressure of a cylinder included in the internal combustion engine at a plurality of crank angles;
a heat generation rate calculation step of calculating heat generation rates of the cylinders at a plurality of crank angles, respectively;
an in-cylinder pressure maximum crank angle acquisition step of acquiring an in-cylinder pressure maximum crank angle at which an in-cylinder pressure of the cylinder of the internal combustion engine is maximum;
a knocking determination crank angle region determining step of determining a knocking determination crank angle region as a region between a small side crank angle smaller than the in-cylinder pressure maximum crank angle by a first value and a large side crank angle larger than the in-cylinder pressure maximum crank angle by a second value;
a heat generation rate differentiation step of calculating a differential value of the heat generation rate in the knock determination crank angle region;
a first knock determination step of performing knock determination based on the differential value of the heat generation rate calculated in the heat generation rate differential step.
According to the configuration of the above (1), the knock detection device is configured to perform knock determination based on the heat generation rate in the crank angle region for knock determination. At this time, a crank angle at which the in-cylinder pressure of a cylinder included in the internal combustion engine is maximum (in-cylinder pressure maximum crank angle) is acquired, and the knock determination crank angle region is specified with the in-cylinder pressure maximum crank angle as a reference. Therefore, the knock determination crank angle region can be easily set based on the maximum crank angle of the cylinder internal pressure that can be easily determined from the cylinder internal pressure. Further, by specifying the first value (small crank angle) and the second value (large crank angle) so as to surely include the crank angle at which knocking occurs, it is possible to determine the heat generation rate in the crank angle region based on knocking, and to perform knocking determination with high accuracy.
(2) In several embodiments, based on the structure of (1) above,
the first value and the second value are respectively 3 degrees to 7 degrees.
The inventors of the present invention have found, through earnest studies, that knocking determination can be performed with good accuracy using a differential value of a heat generation rate in a region of ± 3 degrees to 7 degrees of a maximum crank angle of in-cylinder pressure. Therefore, according to the configuration of the above (2), the knock determination accuracy can be improved by setting the region of 3 to 7 degrees of the crank angle at which the cylinder internal pressure is maximum to the knock determination crank angle region.
(3) In some embodiments, based on the configurations of (1) to (2) above,
the first knock determination step acquires a maximum differential heat generation rate at which a differential value of the heat generation rate calculated in the heat generation rate differential step is a maximum value, and determines that knocking is present when the maximum differential heat generation rate is larger than a first knock determination threshold value.
According to the configuration of the above (3), knock determination can be easily performed by comparing the maximum value of the differential value of the heat generation rate in the knock determination crank angle region with the threshold value.
(4) In several embodiments, based on the structure of (3) above,
further, there is a knock intensity determination step of determining a magnitude of knock intensity of the knock in a case where it is determined in the first knock determination step that the knock exists,
the knock intensity determination step includes:
a reference differential heat generation rate acquisition step of acquiring a reference differential heat generation rate in which a differential value of the heat generation rate is a maximum value, which is a reference crank angle region that is a region between a crank angle smaller by a third value than the small crank angle and the small crank angle;
a knock intensity determination step of determining that the knock intensity is strong when the magnitude of the maximum differential heat generation rate with respect to the reference differential heat generation rate is larger than a knock intensity determination threshold, and determining that the knock intensity is weak when the magnitude of the maximum differential heat generation rate with respect to the reference differential heat generation rate is equal to or smaller than the knock intensity determination threshold.
According to the configuration of the above (4), even when it is determined that knocking is present, the knock intensity can be determined. Thus, for example, by controlling the ignition timing in accordance with the magnitude of the knock intensity, the internal combustion engine can be operated as efficiently as possible while avoiding damage to the internal combustion engine due to knocking.
(5) In some embodiments, based on the configurations of (1) to (4) above,
further, there is a second knock determination step of determining that the knock having a strong knock intensity has been detected in a case where a maximum heat generation rate of the heat generation rates is larger than a second knock determination threshold value.
With the configuration of (5), knocking with a strong knock intensity can be detected quickly. This makes it possible to more reliably prevent the internal combustion engine from being damaged by knocking.
(6) In some embodiments, based on the configurations (1) to (5) above,
the heat generation rate calculation step calculates the heat generation rate for each of the plurality of crank angles using the cylinder pressure acquired in the cylinder pressure acquisition step.
According to the configuration of the above (6), the in-cylinder pressure is information obtained to obtain the maximum in-cylinder pressure crank angle, and the heat generation rate can be easily obtained by performing calculation using the in-cylinder pressure without using another configuration such as a sensor for obtaining the heat generation rate.
(7) A knock detection device according to at least one embodiment of the present invention is a knock detection device for detecting knocking of an internal combustion engine, and includes: the knock detection device includes a cylinder pressure sensor capable of detecting a cylinder pressure of a cylinder included in an internal combustion engine, and a crank angle sensor capable of detecting a crank angle of the internal combustion engine, and includes:
a cylinder pressure acquisition unit that acquires the cylinder pressure detected by the cylinder pressure sensor at a plurality of crank angles;
a heat generation rate calculation unit that calculates heat generation rates of the cylinders at the plurality of crank angles, respectively;
a maximum-cylinder-pressure crank angle acquiring unit that acquires a maximum cylinder-pressure crank angle at which a cylinder pressure of the cylinder of the internal combustion engine is maximum;
a knock determination crank angle region determination portion that determines a knock determination crank angle region that is a region between a small side crank angle smaller than the maximum in-cylinder pressure by a first value and a large side crank angle larger than the maximum in-cylinder pressure by a second value;
a heat generation rate differentiation unit that calculates a differentiation value of the heat generation rate in the knock determination crank angle region;
and a first knock determination unit that performs knock determination based on the differential value of the heat generation rate calculated by the heat generation rate differential unit.
According to the configuration of (7), as in (1), knock determination can be performed more accurately and easily.
(8) In several embodiments, based on the structure of (7) above,
the first value and the second value are respectively 3 degrees to 7 degrees.
According to the configuration of (8) above, as in (2) above, the knock determination accuracy can be improved.
(9) In some embodiments, based on the configurations of (7) to (8) above,
the first knock determination unit acquires a maximum differential heat generation rate at which a differential value of the heat generation rate calculated by the heat generation rate differential unit is a maximum value, and determines that knocking is present when the maximum differential heat generation rate is greater than a first knock determination threshold value.
According to the configuration of (9) above, knock determination can be easily performed as in (3) above.
(10) In several embodiments, based on the structure of (9) above,
further, the knock determination unit determines a level of knock intensity of the knock in a case where the first knock determination unit determines that the knock exists,
the knock intensity determination unit includes:
a reference differential heat generation rate acquisition unit that acquires a reference differential heat generation rate in which a differential value of the heat generation rate is a maximum value in a reference crank angle region that is a region between a crank angle smaller by a third value than the small crank angle and the small crank angle;
and a knock intensity determination unit configured to determine that the knock intensity is strong when the magnitude of the maximum differential heat generation rate with respect to the reference differential heat generation rate is larger than a knock intensity determination threshold, and determine that the knock intensity is weak when the magnitude of the maximum differential heat generation rate with respect to the reference differential heat generation rate is equal to or smaller than the knock intensity determination threshold.
According to the configuration of the above (10), similarly to the above (4), the knock intensity can be determined even when it is determined that knocking is present. In this way, the ignition timing is controlled in accordance with the magnitude of the knock intensity, whereby the internal combustion engine can be operated as efficiently as possible while avoiding damage to the internal combustion engine due to knocking.
(11) In some embodiments, based on the configurations (7) to (10) described above,
the knock determination unit further includes a second knock determination unit configured to determine that the knock having a strong knock intensity has been detected when a maximum heat generation rate of the heat generation rates is larger than a second knock determination threshold value.
According to the configuration of (11), as in (5), knocking with a strong knock intensity can be detected quickly. This makes it possible to more reliably prevent the internal combustion engine from being damaged by knocking.
(12) In some embodiments, based on the configurations (7) to (11) described above,
the heat generation rate calculation unit calculates the heat generation rate for each of the plurality of crank angles using the in-cylinder pressure acquired by the in-cylinder pressure acquisition unit.
According to the configuration of the above (12), similarly to the above (6), it is not necessary to use another configuration such as a sensor for acquiring a heat generation rate, and the heat generation rate can be easily obtained.
ADVANTAGEOUS EFFECTS OF INVENTION
According to at least one embodiment of the present invention, a knock detection method capable of detecting knocking more easily and with high accuracy based on a heat generation rate in a cylinder of an internal combustion engine can be provided.
Drawings
Fig. 1 is a diagram generally showing the configuration of an internal combustion engine having a knock detection device that executes a knock detection method according to an embodiment of the present invention.
Fig. 2 is a functional block diagram showing a configuration of a knock detection device according to an embodiment of the present invention.
Fig. 3 is a flowchart illustrating a knock detection method according to an embodiment of the present invention.
Fig. 4 is a diagram illustrating a change curve of an in-cylinder pressure of a cylinder (block) of an internal combustion engine according to an embodiment of the present invention.
Fig. 5 is a diagram showing a heat generation rate change curve obtained based on the cylinder internal pressure change curve of fig. 4.
Fig. 6 is a view showing a heat generation rate differential curve obtained by differentiating the heat generation rate change curve of fig. 5.
Fig. 7 is a functional block diagram showing the configuration of a knock detection device according to an embodiment of the present invention, and the knock detection device further includes a second knock determination unit.
Fig. 8 is a flowchart showing a knock detection method according to an embodiment of the present invention, and the knock determination method further has a second knock determination step.
Detailed Description
Several embodiments of the present invention will be described below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described as the embodiments or shown in the drawings are not intended to limit the scope of the present invention, and are merely illustrative examples.
On the other hand, expressions such as "configure", "equip", "have", "include" or "have" one structural principal component are not exclusive expressions which exclude the presence of other structural principal components.
Fig. 1 is a diagram schematically showing the configuration of an
First, an
Further, an intake pipe 26 for supplying a mixed gas of air and fuel to the
In the embodiment shown in fig. 1 to 2, as shown in the drawing, the
Next, a
In some embodiments, as shown in fig. 2, the
In the embodiment shown in fig. 1 to 2, the
Next, the above-described configuration of the
The cylinder
The cylinder internal
The heat generation
The maximum in-cylinder pressure crank
The knock determination crank angle
Then, knock determination is performed by analyzing the knock determination crank angle region Rj by the heat generation
The heat generation
The first
Next, a knock detection method performed by the
As shown in fig. 3, the knock detection method is a knock detection method for detecting knocking of the
Next, the above steps will be described according to the execution steps of the flowchart shown in fig. 3.
In step S1 of fig. 3, a cylinder pressure acquisition step is executed. This step is a step of executing the processing equivalent to the above-described cylinder
In step S2, a heat generation rate calculation step is executed. This step is a step of performing the processing equivalent to the heat generation
In step S3, a cylinder internal pressure maximum crank angle acquisition step is executed. This step is a step of performing the processing equivalent to the above-described maximum cylinder crank
The knocking determination crank angle region determining step is executed in step S4. This step is a step of performing the processing equivalent to that of the knock determination crank angle
The heat generation rate differentiation step is performed in step S5. This step is a step of performing the processing equivalent to the heat generation
The first knock determination step is executed in step S6(S6a, S6b, S6y, S6 n). This step is a step of performing the processing equivalent to that of the first
In the example of fig. 6, the maximum differential heat generation rate Dmax of the knock determination crank angle region Rj at the crank angle θ is D3 in the normal state indicated by the broken line, D2 in the case where the knock indicated by the thin solid line is weak, and D1 in the case where the knock indicated by the thick solid line is strong. In addition, D1 was larger than D2, and D2 was larger than D3 (D1 > D2 > D3). The first knock determination threshold Dth is set to a value smaller than D1 and D2 and larger than D3. Therefore, it is determined that knocking is present in the heat generation rate differential curves cqd(s) (when knocking is strong) and cqd (w) (when knocking is weak) in which the maximum differential heat generation rates Dmax are D1 and D2, respectively. On the other hand, it is determined that knocking is not present in the heat generation rate differential curve cqd (n) (normal time) having the maximum differential heat generation rate Dmax of D3.
The
In some embodiments, the first value R1 and the second value R2 that divide the knock determination crank angle region Rj are 3 degrees to 7 degrees, respectively. The first value R1 and the second value R2 are preferably in the range of 4 degrees to 6 degrees, and particularly preferably 5 degrees. For example, when the first value R1 and the second value R2 are each 5 degrees, the knock determination crank angle region Rj is a region where the crank angle θ is between θ max-5 degrees and θ max +5 degrees (θ max-5 degrees ≦ Rj ≦ θ max +5 degrees). In the example of fig. 4, the maximum in-cylinder crank angle θ max is θ mn in the in-cylinder pressure variation curve cp (n) at normal time, θ ms in the in-cylinder pressure variation curve cp(s) at strong knock, and θ mw in the in-cylinder pressure variation curve cp (w) at weak knock, and therefore, the knock determination crank angle region Rj is θ mm to 5 degrees ≦ Rj (cp (n)) ≦ θ mn +5 degrees at normal time, θ m to 5 degrees ≦ Rj (cp (s)) ≦ θ ms +5 degrees at strong knock, and θ mw to 5 degrees ≦ Rj (cp (w)) ≦ θ mw +5 degrees at weak knock, respectively. Although the first value R1 and the second value R2 are described as being equal to 5 degrees, the first value R1 and the second value R2 may be different values.
The knock determination crank angle region Rj is a region of the crank angle θ in which knock determination can be accurately performed by using a differential value of the heat generation rate Q' in a region of ± 3 degrees to 7 degrees of the maximum cylinder internal pressure crank angle θ max, as a result of earnest study by the inventors. Therefore, according to the above configuration, the knock determination accuracy can be improved by setting the region of ± 3 degrees to 7 degrees (preferably ± 4 degrees to 6 degrees, and particularly preferably 5 degrees) of the maximum cylinder internal pressure crank angle θ max as the knock determination crank angle region Rj.
In some embodiments, as shown in fig. 2 (and also in fig. 7 described later), the
A knock detection method according to this embodiment will be described. As shown in fig. 3 (and also in fig. 8 described later), the knock detection method further has a knock intensity determination step (S7) of determining the intensity of knock for which the presence of knock has been determined, in the case where it is determined in the above-described first knock determination step (step S6 y). More specifically, the knock intensity determination step (S7) includes: a reference differential heat generation rate acquisition step (S7a) of acquiring a reference differential heat generation rate Q ' b in which the differential value of the heat generation rate Q ' is maximum, the reference differential heat generation rate Q ' being a reference crank angle region Rb between the crank angle θ smaller than the small crank angle θ S by the third value R3 and the small crank angle θ S; and a knock intensity determination step (S7b, S7y, S7n) of determining that the knock intensity is strong when the magnitude of the maximum differential heat generation rate Dmax with respect to the reference differential heat generation rate Q 'b is larger than the knock intensity determination threshold L, and determining that the knock intensity is weak when the magnitude of the maximum differential heat generation rate Dmax with respect to the reference differential heat generation rate Q' b is equal to or smaller than the knock intensity determination threshold L. The reference differential heat generation rate acquisition step (S7a) is a step of performing a process equivalent to that of the reference differential heat generation
The knock intensity determination step (S7) is explained with reference to the flowchart of fig. 3, and after the above-described step S6y, the knock intensity determination step (S7) is executed. That is, the reference differential heat generation rate acquisition step is executed in step S7a, and the magnitude (Dmax ÷ Q 'b) of the maximum differential heat generation rate Dmax with respect to the reference differential heat generation rate Q' b is compared with the knock intensity determination threshold L in the next step S7 b. Then, when the comparison result in step S7b is Yes (Dmax ÷ Q' b > L), it is determined in step S7y that the knock intensity is strong. On the other hand, if the comparison result in step S7b is No (Dmax ÷ Q' b ≦ L), it is determined in step S7n that the knock intensity is weak.
In the embodiment shown in fig. 1 to 3, the third value R3 is 15 degrees. In the example of fig. 6, the reference differential heat generation rate Q' b is D4 in both the strong knock period and the weak knock period. As a result of comparing the maximum differential heat generation rate Dmax ÷ Q' b with the knock intensity determination threshold L, when the knock is strong, D1 ÷ D4 > L is satisfied, thereby determining that the knock intensity is strong, and when the knock is weak, D2 ÷ D4 ≦ L is satisfied, thereby determining that the knock intensity is weak.
In the embodiment shown in fig. 3, when it is determined in step S7y that the knock intensity is strong, the ignition timing is immediately corrected, for example, by retarding the ignition timing in the next step S8. This is to quickly prevent the
According to the above configuration, the knock intensity can be determined even when it is determined that knocking is present. Thus, for example, by controlling the ignition timing in accordance with the magnitude of the knock intensity, the
Next, with reference to fig. 7 to 8, several other embodiments of the knock determination and the intensity determination will be described. Fig. 7 is a functional block diagram showing the configuration of a knock detection device according to an embodiment of the present invention, and the
In the embodiment shown in fig. 1 to 3, knock determination and intensity determination are performed based on the differential value of the heat generation rate Q'. In some other embodiments, as shown in fig. 7 to 8, knock determination and intensity determination may be performed based on the heat generation rate Q'. This is because, as shown in fig. 5, when the maximum value of the heat generation rate Q ' is too large, there is a high possibility that strong knocking occurs, and therefore, it is not necessary to calculate the differential value of the heat generation rate Q ', and it is possible to more quickly determine knocking using the heat generation rate Q '.
Specifically, as shown in fig. 7, the
However, in other embodiments, the first
A knock detection method according to the present embodiment will be described with reference to fig. 8. As shown in fig. 8, the knock detection method further has a second knock determination step (S4-2: S4 a-S4 c) of determining that knocking of strong knock intensity has been detected in the case where the maximum heat generation rate Q' max is larger than the second knock determination threshold Lq. This step is a step of performing the processing equivalent to that of the second
The steps S1 to S4 in fig. 8 are the same as in fig. 2, and the second knock determination step (S4-2) is executed after the step S4 and the step S5 in fig. 2 are inserted into the flowchart in fig. 8. In more detail, in step S4a, the maximum heat generation rate Q' max of the knock determination crank angle region Rj is acquired. Then, in the next step S4b, the maximum heat generation rate Q' max is compared with the second knock determination threshold Lq. Then, as a result of the comparison in step S4b, in the case where the maximum heat generation rate Q 'max is greater than the second knock determination threshold Lq (Q' max > Lq), it is determined in step S4c that knocking with a strong knock intensity has been detected. Conversely, as a result of the comparison in step S4b, when the maximum heat generation rate Q 'max is equal to or less than the second knock determination threshold Lq (Q' max ≦ Lq), the subsequent steps are executed as a case where knocking having a strong knock intensity is not detected in the second knock determination step. That is, the heat generation rate differentiation step is executed in step S5 described above, and the first knock determination step (S6a, S6b, S6y, S6n of fig. 3) is executed in step S6. Thereafter, the ignition timing setting, which is not shown in fig. 8, may be corrected (step S8 or step S9 in fig. 3). In the embodiment shown in fig. 8, although the knock intensity determination step is executed in step S7 after step S6, the present invention is not limited to this, and the knock intensity determination step may be omitted in other embodiments.
In the example of fig. 5, with respect to the heat generation rate change curve cq(s) indicated by the thick solid line, the maximum heat generation rate Q 'max of the heat generation rate Q' in the knock determination crank angle region Rj is the peak of the second peak value, which exceeds the second knock determination threshold Lq. Therefore, the relationship of Q' max > Lq is established, and it is determined that knocking with strong knock intensity has been detected. On the other hand, in the heat generation rate change curve cq (w) indicated by the thin solid line, the maximum heat generation rate Q 'max of the heat generation rate Q' in the knock determination crank angle region Rj is also the peak of the second peak value, but the peak of the second peak value is lower than the second knock determination threshold Lq. Therefore, the relationship Q' max ≦ Lq does not determine that knocking with a strong knock intensity is detected. Similarly, with respect to the heat generation rate variation curve cq (n) indicated by the broken line, the maximum heat generation rate Q 'max of the heat generation rate Q' in the knock determination crank angle region Rj is the peak of the first peak value, which is also lower than the second knock determination threshold Lq. Therefore, the relationship of Q' max ≦ Lq holds, and it is not determined that knocking with strong knock intensity is detected.
In the above-described embodiments shown in fig. 7 to 8, the description has been given of the case where the maximum heat generation rate Q 'max belongs to the knock determination crank angle region Rj, but in other embodiments, the maximum heat generation rate Q' max may be obtained from all the crank angles θ of the combustion cycle, not limited to the knock determination crank angle region Rj.
According to the above configuration, knocking with a strong knock intensity can be detected quickly. This can more reliably prevent the
The present invention is not limited to the above embodiments, and includes a mode in which modifications are added to the above embodiments, and a mode in which the above modes are appropriately combined.
For example, in the above-described embodiment, the heat generation rate Q ' is calculated using the in-cylinder pressure P of the cylinder of the
Description of the reference numerals
1 a knock detection device; 11 a cylinder internal pressure acquisition unit; 12 a heat generation rate calculation unit; 13 a cylinder internal pressure maximum crank angle acquisition unit; 14 a knock determination crank angle region determination section; 15 heat generation rate differential parts; 16 a first knock determination unit; 17a knock intensity determination unit; 17a reference differential heat generation rate acquisition unit; 17b a knock intensity determination unit; 18 a second knock determination unit; 2, an internal combustion engine; 21 cylinder block (cylinder); 22 a piston; 23 connecting rods; 24 crankshaft; 25a combustion chamber; 25a sub-chamber; 25b a main chamber; 25c, spraying holes; 26 an air supply pipe; 26v supply valve; 27 an exhaust pipe; 27v exhaust valve; 28 a spark plug; 29 a mixer; 29f fuel supply pipe; 29v fuel regulating valve; 3 cylinder internal pressure sensor; 4 crank angle sensor; 7 ignition timing control means; q generates heat; q' heat generation rate; q' max maximum heat generation rate; q' b reference differential heat generation rate; p, in-cylinder pressure; the maximum value of pressure in Pmax cylinder; theta crank angle; r monitors a crank angle region; rj knock determination crank angle region; an Rb reference crank angle region; a first value of R1; r2 second value; a third value of R3; cp cylinder internal pressure variation curve; cq heat generation rate change curve; cqd differential heat generation curve; dmax maximum differential heat generation rate; dth a first knock determination threshold value; an L knock intensity determination threshold value; lq the second knock determination threshold value.
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