JP3750428B2 - vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle that performs automatic stop and restart of an engine.
[0002]
[Prior art]
When the vehicle is temporarily stopped due to a signal, etc. while driving, the engine is automatically stopped, and when it is started, the engine is automatically started again to improve fuel economy. There is a vehicle having an automatic engine stop / restart function (see Japanese Patent Application Laid-Open No. 8-291725).
[0003]
[Problems to be solved by the invention]
By the way, when the hydraulic pressure is supplied to the automatic transmission with the mechanical pump driven by the engine, the hydraulic pressure cannot be supplied to the automatic transmission when the engine stops due to the automatic engine stop. Also, an electric pump driven by a battery is provided, and when a start-start operation such as the accelerator pedal being depressed when the engine is stopped, this electric pump is used to raise the hydraulic pressure and put the forward clutch in the start shift state. In some cases, the engine is automatically restarted and started (see Japanese Patent Application Laid-Open No. 8-14076).
[0004]
However, since the hydraulic pressure does not rise immediately even if the electric pump is operated, if the timing for operating the electric pump is the same as the start-start operation, it is directly affected by the delay of the hydraulic pump hydraulic pressure. That is, if the engine is started and the vehicle is started after the hydraulic pressure of the electric pump rises, the vehicle cannot be started quickly. On the other hand, if the engine is started without waiting for the hydraulic pressure to rise, the forward clutch is not sufficiently engaged and the engine is greatly blown up, and a torque shock occurs when the clutch is engaged thereafter.
[0005]
In view of this, the present invention provides agility by starting the operation of the electric pump and maintaining the hydraulic pressure rising within a delay period from when the automatic engine stop condition is satisfied to when the engine is actually stopped. The purpose is to enable the start of a simple vehicle.
[0006]
[Means for Solving the Problems]
As shown in FIG. 10, the first invention includes an engine 41, an electric motor 42 that rotates in synchronization with the engine 41, an automatic transmission 43 that transmits the output of the engine 41 and the electric motor 42 to driving wheels, In a vehicle provided with a controller 44 having a function 45 for automatically stopping the engine 41 after a predetermined delay period DLY when another driving condition is satisfied and restarting the engine 41 when another predetermined driving condition is satisfied (note that (The figure does not show the connection state of the engine, electric motor, and transmission), a mechanical pump 46 driven by the engine 41, an electric pump 47 driven by electric power from the battery, and the pumps 46, 47 Means 48 for supplying the generated hydraulic pressure to the automatic transmission 43, and the controller 44 includes the electric power within the delay time DLY. A function 49 for starting the operation of the pump 47.
[0007]
A second invention includes means for detecting the hydraulic pressure generated by the electric pump in the first invention, and prohibits the engine from being stopped when the detected hydraulic pressure is not greater than or equal to a predetermined value Pt0 at the end of the delay period. To do.
[0008]
According to a third aspect, in the first aspect, the hydraulic target value of the electric pump is individually set during the delay period and after the engine is stopped, and the hydraulic target value Pt1 during the delay period is set during the subsequent engine stop. Lower than the target hydraulic pressure value Pt2.
[0009]
In a fourth aspect of the present invention, the target hydraulic pressure value Pt1 during the delay period is set within a range in which the hydraulic pressure follow-up delay does not occur when shifting from the delay period to the subsequent engine stop in the third aspect of the invention.
[0010]
According to a fifth aspect, in the third aspect, the hydraulic target values Pt1 and Pt2 of the electric pump during the delay period and the subsequent engine stop are changed according to the oil temperature.
[0011]
In a sixth aspect of the invention, the waiting period Tp until the operation of the electric pump is started in the first aspect is changed according to the oil temperature.
[0012]
According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the hydraulic pressure supply means from the hydraulic pressure supply means to the automatic transmission is an element required for starting the vehicle in the automatic transmission (for example, front and rear The hydraulic chamber of the advance clutch and the pulley hydraulic chamber when the automatic transmission is CVT are limited.
[0013]
【The invention's effect】
According to the first aspect, since the operation of the electric pump is started during the delay period, the hydraulic pressure of the electric pump rises until the engine is stopped. That is, even if the engine and the mechanical pump are stopped due to the end of the delay period, the hydraulic pressure of the electric pump rises, so that the transmission hydraulic pressure is continuously maintained. Therefore, even if a start / start operation such as depressing the accelerator pedal is performed immediately after shifting to the engine stop state, it is possible to start the engine immediately, connect the forward clutch, and start the vehicle quickly, and the clutch engagement delay No engine blow-up or torque shock will occur.
[0014]
According to the second invention, at the end of the delay period, it is possible to prevent a situation in which the engine and the mechanical pump stop without the hydraulic pressure of the electric pump rising and the hydraulic pressure of the transmission decreases. Thus, even if a start / start operation is performed immediately after the end of the delay period, the engine start and the clutch engagement can be performed immediately.
[0015]
According to the third aspect of the invention, the drive load of the electric pump is reduced due to the decrease in the hydraulic target value during the delay period, so that the power consumption can be saved accordingly.
[0016]
According to the fourth aspect of the invention, the target hydraulic pressure can be ensured immediately at the time of transition to the engine stop state, so that the vehicle startability immediately after the transition to the engine stop state can be secured.
[0017]
Since it is considered that the hydraulic pressure of the electric pump rises faster as the oil temperature is higher, according to the fifth invention, the hydraulic target value of the electric pump can be set as low as possible in accordance with the oil temperature, and the result Can save power consumption.
[0018]
According to the sixth aspect of the invention, when the temperature is relatively high and the hydraulic pressure rises quickly, the operation start timing of the electric pump can be delayed. Therefore, the operation period of the electric pump is reduced, and power consumption can be saved.
[0019]
According to the seventh aspect of the invention, the oil leakage flow rate when the engine is stopped can be minimized. As a result, the load on the electric pump can be reduced, and the power consumption can be reduced.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, 1 is an engine, 3 is a continuously variable automatic transmission, and a motor generator (electric motor) 2 is disposed between them. The rotation of the engine 1 or the motor generator 2 is transmitted from the continuously variable automatic transmission 3 to a drive wheel (not shown) via the drive shaft 7.
[0021]
As the engine 1, a diesel engine can be provided in addition to a gasoline engine, and a stepped automatic transmission with a torque converter or a starting clutch can be used instead of the continuously variable automatic transmission 3.
[0022]
The continuously variable automatic transmission 3 includes a torque converter 4, a forward / reverse switching mechanism 5, and a metal belt 6 wound around the variable pulleys 6a and 6b. By changing the pulley ratio of the variable pulleys 6a and 6b, The speed ratio transmitted through the belt 6 changes. In order to drive the variable pulleys 6a and 6b so that the target speed ratio of the continuously variable automatic transmission 3 is set in accordance with the driving state and matches the speed ratio that is the ratio of the actual input speed to the output speed. The primary hydraulic pressure and the secondary hydraulic pressure are controlled.
[0023]
The forward / reverse switching mechanism 5 reverses the direction of output rotation between forward and reverse, and the torque converter 4 transmits the input rotational torque to the output side via fluid force, and at the time of extremely low speed rotation on the input side. It is acceptable to stop rotation on the output side.
[0024]
The motor generator 2 is directly connected to the crankshaft of the engine 1 or connected via a belt or chain, and rotates in synchronization with the engine 1. The motor generator 2 functions as a motor or a generator, and its function, rotation speed, power generation amount, and the like are controlled by the power control unit 12.
[0025]
When the motor generator 2 functions as a motor that supplements the output of the engine 1 or functions as a motor for starting the engine 1, the current from the battery 13 is supplied via the power control unit 12, and the running energy of the vehicle When the battery 13 functions as a generator to recover the battery, the battery 13 is charged by the current generated through the power control unit 12.
[0026]
Further, an automatic stop / restart controller 10 is provided to automatically stop the engine when the vehicle is temporarily stopped, etc., and then automatically restart the engine 1 when starting the vehicle. And the engine 1 is started by the motor generator 2 when starting.
[0027]
Therefore, the automatic stop / restart controller 10 receives signals from the engine speed sensor 9, the brake sensor 11, the accelerator sensor 15, the shift position sensor 17 of the continuously variable automatic transmission 3, the vehicle speed sensor 18, and the like. Control of automatic stop and start based on
[0028]
The vehicle is provided with a mechanical pump driven by an engine and an electric pump driven by a battery in order to supply hydraulic pressure to the continuously variable automatic transmission 3.
[0029]
This will be explained with reference to FIG. 2. In FIG. 2, reference numeral 21 denotes a mechanical pump connected to the torque converter 2, and the hydraulic pressure generated by the mechanical pump 21 during operation of the engine is adjusted by the line pressure control valve 22. The hydraulic pressure thus adjusted is supplied to the hydraulic chamber 24 of the forward / reverse clutch via the hydraulic pressure supply passage 23.
[0030]
In addition, a shutoff valve 27 is interposed in a hydraulic pressure supply passage 25 that connects the mechanical pump 21 and the pulley hydraulic chamber 26 of the continuously variable automatic transmission, and the shutoff valve 27 is opened during engine operation. The pressurized hydraulic pressure is also supplied to the pulley hydraulic chamber 26 of the continuously variable automatic transmission. In this case, the check valve 28 can prevent the hydraulic pressure from the mechanical pump 21 from being transmitted to the electric pump 14.
[0031]
On the other hand, the electric pump 14 is driven by a DC motor 29 and supplies necessary hydraulic pressure to the hydraulic chamber 24 of the forward / reverse clutch and the pulley hydraulic chamber 26 of the continuously variable transmission regardless of the operation of the engine. In this case, it is possible to prevent the hydraulic pressure from the electric pump 14 from being transmitted to the mechanical pump 21 by shutting off the shutoff valve 27.
[0032]
Reference numeral 31 denotes a relief valve that opens and returns oil to the electric pump 14 when the discharge pressure of the electric pump 14 exceeds a specified value. A manual valve 32 has a function of releasing the hydraulic pressure of the forward clutch.
[0033]
The electric pump 14 is also controlled by the automatic stop / restart controller 10, and when a start / start operation such as depressing the accelerator pedal is performed while the engine is stopped, the forward clutch is immediately engaged to start the vehicle. Thus, the electric pump 14 starts to operate within a delay period from when the engine automatic stop condition is satisfied to when the engine is stopped, and the hydraulic pressure is raised and held.
[0034]
This will be explained with reference to FIG. 3. When the vehicle is stopped at the timing t0 in the idle state, a condition for automatically stopping the engine at the timing t0 that is the vehicle stop timing is satisfied, and the delay period DLY has elapsed from this t0. The engine is actually stopped at the timing t2. For this reason, although sufficient transmission oil pressure (transmission line oil pressure) is maintained by the operation of the mechanical pump until the timing of t2, the hydraulic pressure of the mechanical pump is reduced to zero from the timing of t2.
[0035]
In this case, the automatic stop / restart controller 10 starts the operation of the electric pump at timing t1 when the standby period Tp has elapsed from t0 which is the start of the delay period DLY. At that time, during the delay period, the hydraulic pressure target value of the electric pump is set to a lower value Pt1, and after the delay period DLY has passed, the hydraulic pressure target value is increased to a value Pt2 larger than Pt1. Then, the hydraulic target value is increased to a value Pt3 larger than Pt2 from the timing t3 when the start / start operation is performed thereafter.
[0036]
Further, if the hydraulic pressure generated by the electric pump becomes higher due to the decrease in the hydraulic pressure of the mechanical pump from the engine stop timing t2, the oil will flow backward from the electric pump to the mechanical pump. The shut-off valve 27 is closed in accordance with the decrease in hydraulic pressure of the mechanical pump.
[0037]
On the other hand, when the engine is restarted by the start-start operation, the mechanical pump works and the hydraulic pressure rises, so that the operation of the electric pump is stopped at the timing t4 when the hydraulic pressure by the mechanical pump is determined to be sufficient. Open the shut-off valve.
[0038]
Next, the control content executed by the controller 10 will be described according to the following flowchart.
[0039]
First, FIG. 4 is for performing an automatic engine stop / restart process, and is executed at regular time intervals (for example, every 10 msec).
[0040]
In step 1, it is checked whether or not the conditions for permitting idle stop (automatic stop) are satisfied. Here, the idle stop permission conditions include, for example, the following.
[0041]
(1) The state of charge (SOC) of the battery is within a predetermined range.
[0042]
(2) The cooling water temperature of the engine is in an appropriate range (for example, after completion of warming up).
[0043]
When all the above two conditions are satisfied, it is determined that the idle stop permission condition is satisfied, and the process proceeds to Steps 2, 3, 4, 5, 6 to detect the vehicle speed detected by the vehicle speed sensor 18 and the brake sensor 11. The state of the brake pedal detected by the above, the state of the accelerator pedal detected by the accelerator sensor 15, the automatic stop prohibition flag, and the engine speed are viewed. (3) The vehicle speed is 0 km / h, (4) The brake pedal is depressed, (5) The accelerator pedal is not depressed, and (6) The automatic stop prohibition flag is 0. However, if it is not the idling speed range (for example, 800 rpm or less), the current process is terminated. The setting of the automatic stop prohibition flag will be described later with reference to FIG.
[0044]
When all of the conditions of (7) idle rotation range are satisfied in addition to the conditions of (3), (4), (5), and (6) above, the process proceeds to step 7 and the above (3), (4) It is determined from the flag FCOND (initially set to 0) whether or not all the conditions ▼, ▲ 5, ▲ 6, and ▲ 7 are satisfied for the first time.
[0045]
When FCOND = 0 (when established for the first time), in order to enter the engine stop process, the flag FCOND = 1 is set in step 8 and a delay period (for example, delay time DLY) until the engine is stopped is set. For example, about 2 seconds is set as the delay time DLY.
[0046]
In step 9, it is determined whether or not the engine is stopped. If the engine is stopped, the current process is terminated. When the engine is not stopped, the process proceeds from step 9 to step 10, and the delay time DLY is compared with the counter Td that measures the elapsed time after the delay time DLY is set, and if the counter Td exceeds the delay time DLY. In step 12, engine stop processing is executed. In this process, for example, the torque generated by the motor generator 2 is made zero, and the fuel injection of the engine 1 is stopped. For example, a timer built in the controller 10 may be used as the counter Td.
[0047]
On the other hand, when any of the above conditions (1), (2), (3), (4), (5), or (6) is removed, that is, the brake pedal is released or the accelerator pedal is depressed. Or when the vehicle speed is no longer zero, the flag FCOND = 0 in step 13. Then, in step 14, it is determined whether or not the engine is stopped. If the engine is stopped, the process proceeds to step 15 to perform a process of restarting the engine.
[0048]
The value of the flag FCOND is stored in the RAM.
[0049]
FIG. 5 is for executing the prohibition determination of the automatic engine stop, and is executed at regular time intervals (for example, every 10 msec).
[0050]
When the idle stop permission condition is satisfied in step 21, the delay counter Td used in FIG. 4 is read in step 22, and this is compared with the delay time DLY in step 23.
[0051]
When the counter Td exceeds the delay time DLY, the routine proceeds to step 24, the actual hydraulic pressure generated by the electric pump 14 detected by the sensor 33 (see FIG. 2) is read, and this is compared with a predetermined value Pt0 at step 25. Here, the predetermined value Pt0 is a determination value for determining whether or not the automatic stop of the engine is prohibited. When the actual hydraulic pressure is Pt0 or less, the automatic stop prohibit flag = 1 in step 26 to prohibit the automatic stop of the engine. And Since this flag = 1, it is not possible to proceed to step 6 and subsequent steps in FIG. 4, and therefore, automatic engine stop is prohibited.
[0052]
This is because, when the rising of the hydraulic pressure of the electric pump 14 is not equal to or greater than the predetermined value Pt0 at the end of the delay period, the engine 1 and the mechanical pump 21 are prevented from rising without prohibiting the engine stop. This is to avoid the situation where the transmission stops and the hydraulic pressure of the transmission decreases. As a result, even if a start operation is performed immediately after the end of the delay period, the clutch can be immediately engaged and the vehicle can be started quickly, and engine blow-up and torque shock due to clutch engagement delay may occur. Absent.
[0053]
On the other hand, when the actual hydraulic pressure exceeds the predetermined value Pt0, it is not necessary to prohibit the automatic stop of the engine, so the routine proceeds to step 27 and the automatic stop prohibition flag = 0 is set.
[0054]
6 and 7 are for controlling the electric pump 14, which is also executed at regular intervals (for example, every 10 msec).
[0055]
In FIG. 6, in step 41, the flag FCOND stored in the RAM is viewed. When FCOND = 1, the routine proceeds to step 42 to check whether the engine is stopped. When the engine is not stopped (that is, either during the delay period or when the automatic stop prohibition flag = 1), the routine proceeds to step 43 and the operating state of the electric pump 14 is checked.
[0056]
If the electric pump 14 is not in operation, the delay counter Td used in FIG. 5 is read in step 44, and this is compared with a predetermined value Tp in step 45. Here, the predetermined value Tp determines the operation standby time of the electric pump 14. For this reason, when Td is equal to or less than Tp, the process proceeds to step 46 to hold the electric pump in a non-operating state. When Td exceeds Tp, it is determined that the operation timing of the electric pump has come, and the process proceeds to steps 47 and 48. The predetermined value Pt1 (Pt1> Pt0) is set as the hydraulic target value Pt of the electric pump, and the operation of the electric pump is started. Then, from the next time until the engine is stopped, the process proceeds from step 43 to steps 47 and 48, whereby the hydraulic pressure generated by the electric pump is controlled to a predetermined value Pt1.
[0057]
Here, the predetermined value Pt1 that is the hydraulic target value during the delay period is set lower than the predetermined value Pt2 (which will be described later immediately) that is the hydraulic target value during the subsequent engine stop. If the target hydraulic pressure is set low, the driving load of the electric pump is reduced, and the power consumption can be saved accordingly. In addition, by determining the value of Pt1 within a range in which the target hydraulic pressure can be secured immediately upon transition to the engine stop state thereafter, vehicle startability immediately after transition to the engine stop state can be secured.
[0058]
Note that the shutoff valve 27 is kept open until the delay period ends (steps 42 and 49).
[0059]
Thereafter, when the engine is stopped, the routine proceeds from step 42 to step 50, where a predetermined value Pt2 (Pt2> Pt1) is set as the hydraulic target value Pt of the electric pump, and then the processing of step 51 is executed. Steps 50 and 51 are repeated until the start / start operation is performed from the next time, whereby the hydraulic pressure generated by the electric pump is increased to a predetermined value Pt2.
[0060]
At this time, the shutoff valve 27 is closed (steps 42 and 52). This is because the hydraulic pressure of the mechanical pump decreases due to the engine stop, and oil is prevented from flowing back from the electric pump toward the mechanical pump as the hydraulic pressure of the mechanical pump decreases.
[0061]
On the other hand, when the flag FCOND = 0, the routine proceeds from step 41 in FIG. 6 to step 53 in FIG. When the vehicle is starting and starting, a predetermined value Pt3 (Pt3> Pt2) is set as the hydraulic target value Pt of the electric pump at step 54, and then the processing at steps 55 and 56 is executed. Here, the predetermined value Pt3 is a hydraulic pressure target value at the start and start. From the next time, steps 54, 55, and 56 are repeated until the start / start operation is completed, whereby the hydraulic pressure generated by the electric pump is further increased to a predetermined value Pt3.
[0062]
On the other hand, when the start / start operation is not completed, such as when the start / start operation is not completed, the process proceeds from step 53 to steps 57 and 58, the electric pump is deactivated, and the shut-off valve 27 is opened.
[0063]
The operation waiting time Tp and each of the predetermined values Pt0, Pt1, Pt2, and Pt3 may be constant values, but here, a table containing the contents of FIGS. 8 and 9 is searched from the oil temperature at that time of the transmission oil. By seeking. The reason why the value is lowered as the oil temperature rises is because the hydraulic pressure of the electric pump rises faster as the oil temperature rises.
[0064]
Here, the function and effect of the present embodiment will be described with reference to FIG. 3 again.
[0065]
In the present embodiment, the operation of the electric pump 14 is started at t1 during a delay period until the engine is stopped. During the delay period, the necessary hydraulic pressure is obtained by the mechanical pump 21, so that the hydraulic pressure by the electric pump 14 is not necessary. Therefore, the hydraulic pressure of the electric pump 14 during the delay period is controlled to a smaller value Pt1 so that the hydraulic pressure of the electric pump 14 quickly rises while the engine is stopped after the delay period ends. As a result, the driving load of the electric pump 14 is reduced, and the power consumption can be saved accordingly.
[0066]
In addition, since the predetermined value Pt1 is determined within a range in which the hydraulic pressure follow-up delay does not occur greatly when shifting to the engine stop state after the delay period, the target oil pressure can be secured immediately upon shifting to the engine stop state. As a result, vehicle startability immediately after the transition to the engine stop state can be secured.
[0067]
When the engine is stopped at the end of the delay period, the hydraulic pressure of the electric pump 14 rises to the predetermined value Pt2 with good response, and the hydraulic pressure of the transmission is large even if the operation of the mechanical pump is stopped when the engine stops. It settles at a certain value without deteriorating.
[0068]
When the start / start operation is performed in this state, the hydraulic pressure of the electric pump rises to Pt3 having a higher value than the predetermined value Pt2 with good response. At this time, the hydraulic pressure of the transmission exceeds the required hydraulic pressure (the minimum hydraulic pressure necessary to transmit the engine torque to the transmission without blowing up the engine), and quickly recovers to the value before the engine stopped. (That is, the hydraulic pressure of the transmission required at the time of starting and restarting is ensured instantaneously), so that the engine can be started quickly and the vehicle can be restarted by engaging the clutch.
[0069]
As described above, according to this embodiment, the hydraulic pressure of the electric pump is raised in advance from the delay period before the engine is stopped, so that the transmission hydraulic pressure can be greatly reduced while the engine is stopped. Therefore, it is always easy to start and restart, so that the start and restart can be performed quickly and smoothly.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a configuration of an embodiment of the present invention.
FIG. 2 is a schematic hydraulic pressure supply circuit diagram of the automatic transmission.
FIG. 3 is a waveform diagram for explaining the operation of the embodiment.
FIG. 4 is a flowchart for explaining engine automatic stop / restart processing;
FIG. 5 is a flowchart for explaining determination of prohibition of automatic engine stop.
FIG. 6 is a flowchart for explaining control of the electric hydraulic pump.
FIG. 7 is a flowchart for explaining control of the electric hydraulic pump.
FIG. 8 is a characteristic diagram of an operation standby time Tp.
FIG. 9 is a characteristic diagram of predetermined values Pt0, Pt1, Pt2, and Pt3.
FIG. 10 is a diagram corresponding to a claim of the first invention.
[Explanation of symbols]
1 Engine 2 Motor generator 3 Continuously variable transmission 10 Automatic stop / restart controller 14 Electric pump 21 Mechanical pump 27 Shut-off valve

Claims (7)

An engine, an electric motor that rotates in synchronization with the engine, an automatic transmission that transmits the output of the engine and the electric motor to the drive wheels, and an engine that automatically stops after a predetermined delay period when a predetermined operating condition is satisfied. In a vehicle provided with a controller having a function of restarting the engine when a predetermined operating condition of
A mechanical pump driven by an engine; an electric pump driven by electric power from a battery; and means for supplying hydraulic pressure generated by the pump to the automatic transmission. A vehicle comprising a function of starting the operation of the electric pump. The engine according to claim 1, further comprising means for detecting a hydraulic pressure generated by the electric pump, and prohibiting the engine from being stopped when the detected hydraulic pressure does not exceed a predetermined value at the end of the delay period. vehicle. The hydraulic target value of the electric pump is individually set during the delay period and after the engine is stopped, and the hydraulic target value during the delay period is set lower than the hydraulic target value during the subsequent engine stop. The vehicle according to claim 1. 4. The vehicle according to claim 3, wherein the hydraulic pressure target value during the delay period is set within a range in which a delay in following the hydraulic pressure does not occur when shifting from the delay period to the subsequent engine stop. 5. The vehicle according to claim 3, wherein the hydraulic pressure target value of the electric pump during the delay period and during the subsequent engine stop is changed according to the oil temperature. The vehicle according to claim 1, wherein a waiting period until the operation of the electric pump is started is changed according to an oil temperature. The vehicle according to any one of claims 1 to 6, wherein a destination for supplying hydraulic pressure from the hydraulic pressure supply means to the automatic transmission is limited to elements required for starting the vehicle in the automatic transmission. .

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