JP7067314B2 - Control device - Google Patents

Description

The present invention relates to a control device for controlling a vehicle having an engine configured to be capable of using liquid fuel and gaseous fuel.

Conventionally, a vehicle having an engine using a liquid fuel and a gas fuel (so-called bi-fuel vehicle) is known (see Patent Document 1).

Since the combustion speed of gas fuel is generally lower than that of liquid fuel, the startability of the engine is poor. Therefore, in the vehicle of Patent Document 1, the startability of the engine is maintained by supplying liquid fuel instead of gas fuel when the engine is started.

Japanese Patent Application Laid-Open No. 11-324749

Gas fuel (for example, CNG: Compressed Natural Gas) has better fuel efficiency (thermal efficiency) than liquid fuel (for example, gasoline). Therefore, in order to further improve fuel efficiency, it is required to increase the chances of using gaseous fuel and improve fuel efficiency.

Therefore, the present invention has been made in view of the above problems, and is a control device for controlling a vehicle having an engine configured to be able to use liquid fuel and gaseous fuel, and is a control device for starting an engine. It is an object of the present invention to provide a control device having improved fuel efficiency while maintaining the performance.

The control device according to one embodiment is a control device for controlling a vehicle having an engine configured to be able to use liquid fuel and gaseous fuel. The control device determines that the speed of the vehicle is 0 and the rotation speed of the engine is 0 when the engine is restarted from the automatic stop state in which the engine is automatically stopped. Accordingly, the gaseous fuel is selected as the fuel of the engine, and the liquid fuel is selected as the fuel according to the determination that the rotation speed of the engine is larger than 0.

When the engine is started by starting the engine, the temperature inside the engine rises, and the engine shifts to a state where the startability with gaseous fuel is good (for example, a completely warm state where the cooling water temperature of the engine is 80 ° C or higher). do. When the engine is restarted from a state in which the engine is automatically stopped, the engine is usually in a completely warmed state. When the engine is completely warmed up, even if the gas fuel is used instead of the liquid fuel, there is no big difference in the startability of the engine, so that the startability of the engine can be maintained. Therefore, since the opportunity to use the gaseous fuel increases, it is possible to improve the fuel efficiency while maintaining the startability of the engine.

On the other hand, when the engine speed is greater than 0, that is, when the engine is restarted from the automatic stop state (the brake pedal is released or the clutch pedal is depressed) before the engine speed becomes 0. In many cases, the driver wants to start the vehicle at an early stage. In such a case, the startability of the engine can be maintained by selecting a liquid fuel having better startability of the engine in consideration of the intention of the driver.

As described above, by appropriately selecting the liquid fuel and the gaseous fuel according to the situation, it is possible to improve the fuel efficiency while maintaining the startability of the engine.

FIG. 1 is a schematic diagram for explaining a vehicle system according to an embodiment. FIG. 2 is a flowchart for explaining the operation according to the embodiment. FIG. 3 is an explanatory diagram for explaining Examples and Comparative Examples.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the description of the drawings below, the same or similar parts are designated by the same or similar reference numerals. However, it should be noted that the drawings are schematic and the ratio of each dimension is different from the actual one. Therefore, the specific dimensions, etc. should be determined in consideration of the following explanation. In addition, there may be a portion where the relationship and ratio of the dimensions of the drawings are different from each other. In the present specification and the drawings, elements having substantially the same function and configuration are designated by the same reference numerals to omit duplicate description, and elements not directly related to the present invention are omitted from the illustration.

(1) Schematic configuration of the vehicle system The schematic configuration of the vehicle system 1 will be described with reference to FIG. FIG. 1 is a schematic diagram for explaining a vehicle system according to an embodiment.

The vehicle system 1 is provided in a vehicle having an engine 2 configured to be able to use liquid fuel and gaseous fuel.

As shown in FIG. 1, the vehicle system 1 (vehicle) includes an engine 2, an ECU (Engine Control Unit) 3, a fuel tank 4, a fuel switching device 5, an intake manifold 6, a starter 7, a drive wheel 8, a clutch 9, and a speed change. It has a machine 10, a pedal 11, a water temperature sensor 12, a vehicle speed sensor 13, a fuel selection switch 14, an injector 15, and an electromagnetic valve 16.

The engine 2 is a device that serves as a power source for the drive wheels 8. The engine 2 is controlled by the ECU 3. In the engine 2, the fuel contained in the fuel tank 4, which will be described later, is injected by the injector 15, and the injected fuel is burned to generate power to the drive wheels 8.

The ECU 3 is a device (control device) for controlling the engine 2. The ECU 3 controls the engine 2, the fuel switching device 5, and the starter 7. Specifically, the ECU 3 transmits and receives an electric signal to and from the engine 2 and the fuel switching device 5. The ECU 3 controls the starter 7 by transmitting an electric signal to the starter 7. The ECU 3 can control the engine 2 via the starter 7.

The ECU 3 may be composed of a processor, a memory, and a transceiver. The processor and memory may constitute a control unit. The processor includes a CPU (Central Processing Unit). The processor performs various processes described later by executing a program stored in the memory. The memory stores a program executed by the processor and information used for processing by the processor. The transceiver transmits and receives electric signals to and from various devices controlled by the processor (for example, engine 2, fuel switching device 5, etc.). The transceiver receives electrical signals from various devices and outputs them to the processor. In addition, the transceiver transmits the electric signal input from the processor to various devices.

The ECU 3 receives an electric signal from the pedal 11, the water temperature sensor 12, the vehicle speed sensor 13, and the fuel selection switch 14. The ECU 3 can control the engine 2, the fuel switching device 5, and the starter 7 according to the received electric signal.

The fuel tank 4 is a tank (container) in which fuel is stored. Specifically, the fuel tank 4 has a first fuel tank 41 and a second fuel tank 42. The first fuel tank 41 accommodates liquid fuel. The liquid fuel is, for example, gasoline, light oil, or the like. The second fuel tank 42 accommodates gaseous fuel. The gaseous fuel is, for example, CNG (Compressed Natural Gas), LPG (Liquefied Natural Gas), or the like.

The fuel switching device 5 is a device for switching fuel to be sent to the engine 2. The fuel switching device 5 is connected to the first fuel tank 41 and the second fuel tank 42. The fuel switching device 5 sends the fuel selected by the ECU 3 to the engine 2.

The intake manifold 6 is arranged between the fuel switching device 5 and the engine 2. The fuel sent from the fuel switching device 5 is sent to the engine 2 through the intake manifold 6. In the intake manifold 6, fuel is injected from the fuel switching device 5. As a result, fuel is injected into the fuel chamber of the engine 2.

The starter 7 is a device for starting the engine 2. The starter 7 is started by an electric signal from the ECU 3 to start the engine 2. When the engine 2 is started, the temperature of the engine 2 is raised and the engine 2 shifts to a completely warm state.

The drive wheels 8 are driven (rotated) by using the engine 2 as a power source. The clutch 9 transmits the power of the engine 2 to the transmission 10. The clutch 9 may be operated by the clutch pedal 116 described later. The clutch 9 may be automatically controlled without the operation of the driver. The transmission 10 shifts the power of the engine 2 and transmits it to the drive wheels 8.

The pedal 11 transmits the driver's operation to the ECU 3 by an electric signal. The pedal 11 has an accelerator pedal 112 and a brake pedal 114. The pedal 11 may have a clutch pedal 116 or may not have a clutch pedal 116.

The water temperature sensor 12 measures the water temperature of the engine 2. The water temperature sensor 12 can send the measured value to the ECU 3 by an electric signal. The vehicle speed sensor 13 measures the speed of the vehicle. The vehicle speed sensor 13 can send the measured value to the ECU by an electric signal.

The fuel selection switch 14 is a switch operated by the driver. The fuel selected by the driver's operation is transmitted to the ECU 3 by an electric signal.

The injector (fuel injection device) 15 injects fuel into the intake manifold 6. The injector 15 may be controlled by the ECU 3. The injector 15 may be controlled by a driver's operation (for example, depressing the accelerator pedal 112 / releasing the brake pedal 114).

The solenoid valve 16 is arranged between the second fuel tank 42 and the injector 15 in a path through which the liquid fuel passes. In FIG. 1, the solenoid valve 16 is arranged between the second fuel tank 42 and the fuel switching device 5.

The solenoid valve 16 is opened or closed by an electric signal (omitted) from the ECU 3. When the solenoid valve 16 is open, gaseous fuel can pass through the path and reach the injector 15. On the other hand, when the solenoid valve 16 is closed, the gaseous fuel cannot pass through the path and the liquid fuel can reach the injector 15.

The vehicle equipped with the vehicle system 1 may have a sensor for measuring the state of the battery of the vehicle (for example, a lead battery) (not shown). The sensor can measure at least one of the voltage of the battery, the liquid temperature of the battery, and the state of charge of the battery.

The vehicle equipped with the vehicle system 1 can select gas fuel instead of liquid fuel during normal driving. This makes it possible to improve fuel efficiency.

(2) Operation According to the Embodiment The operation according to the embodiment will be described with reference to FIG. FIG. 2 is a flowchart for explaining the operation according to the embodiment.

In FIG. 2, it is assumed that the engine 2 is in operation and the startability of the gaseous fuel is good (complete warm-up state). The complete warm-up state is a state in which the engine 2 can actually be started (the rotation speed of the engine 2 increases) within a predetermined time when the engine 2 is started using the gaseous fuel.

As shown in FIG. 2, in step S10, the ECU 3 determines whether or not the engine 2 is in the automatic stop state in which the engine 2 is automatically stopped. The automatic stop state is a state in which the engine 2 continues to operate at the minimum rotation speed in a no-load state, that is, a so-called idling stop state (idling stop).

The idling stop includes an idling stop when the vehicle is stopped and an idling stop when the vehicle is decelerated. The idling stop when the vehicle is stopped means a state in which the engine 2 is automatically stopped after the vehicle is stopped (that is, when V = 0). The idling stop during deceleration means a state in which the engine 2 is automatically stopped by falling below a predetermined speed (that is, when V> 0) while the vehicle is decelerating.

The ECU 3 can determine whether or not the engine 2 is in an automatic stop state based on the driver information and the vehicle information. The driver information includes information caused by the operation (depressing and / or depressing release) of the pedal 11 (accelerator pedal 112, brake pedal 114, etc.) by the driver. The driver information is, for example, information generated in response to the operation of the pedal and information generated in response to the operation of the switch (for example, the fuel selection switch 14). The vehicle information includes a measured value (water temperature) by the water temperature sensor 12, a measured value (vehicle speed) by the vehicle speed sensor 13, a measured value (battery voltage) by the voltage sensor, and the like. Vehicle information is information measured by a sensor (measuring device) possessed by the vehicle.

The ECU 3 can acquire driver information according to the operation of the driver. The ECU 3 can acquire vehicle information at any timing. The ECU 3 may receive vehicle information periodically or continuously, or may receive it aperiodically. The ECU 3 may request vehicle information from each device (for example, water temperature sensor 12, vehicle speed sensor 13, etc.) that is a source of vehicle information.

The ECU 3 can determine, for example, that it is in the automatic stop state when at least one of the driver information conditions and at least one of the vehicle information conditions are satisfied.

<Conditions for driver information>
・ Release of accelerator pedal 112 ・ Depressing of brake pedal 114 <Conditions for vehicle information>
-The vehicle speed is less than or equal to the specified speed (for example, "0 km / h" or "9-13 km / h").

The ECU 3 may determine that it is in the automatic stop state in consideration of the liquid temperature of the battery, the state of charge of the battery, and the like.

When the ECU 3 determines that the engine 2 is in the automatic stop state, the ECU 3 executes the process of step S20. When the ECU 3 determines that the engine 2 is not in the automatic stop state, the process of step S10 may be repeated.

In step S20, the ECU 3 keeps the solenoid valve 16 open when the engine 2 is in the automatic stop state. As a result, the gaseous fuel in the first fuel tank 41 can be guided to the fuel switching device 5, and the gaseous fuel can be immediately supplied to the engine 2 when the engine 2 is started. Therefore, even if the gaseous fuel is used. The startability of the engine 2 can be maintained.

In step S30, the ECU 3 determines whether or not the starting condition of the engine 2 is satisfied.

The ECU 3 can determine whether or not the starting condition of the engine 2 is satisfied based on the driver information and the vehicle information.

The ECU 3 can determine that the engine 2 start condition is satisfied, for example, when at least one of the driver information conditions and at least one of the vehicle information conditions are satisfied.

<Conditions for driver information>
・ Depressing the accelerator pedal 112 ・ Release the brake pedal 114 <Conditions for vehicle information>
・ The increase in vehicle speed is equal to or greater than the specified value (for example, “2 km / h”).

When the ECU 3 determines that the starting condition of the engine 2 is satisfied, the ECU 3 executes the process of step S40. When the ECU 3 determines that the starting condition of the engine 2 is not satisfied, the ECU 3 repeats the process of step S30.

In step S40, the ECU 3 determines whether or not the vehicle speed (vehicle speed) V is 0. Specifically, the ECU 3 determines whether or not the vehicle speed V is 0 based on the vehicle information (vehicle speed).

When the ECU 3 determines that the vehicle speed V is 0, the ECU 3 performs the process of step S50. When the ECU 3 determines that the vehicle speed V is not 0, that is, the vehicle speed V is larger than 0, the ECU 3 performs the process of step S60.

In step S50, the ECU 3 determines whether or not the rotation speed N of the engine 2 is 0. Specifically, the ECU 3 determines whether or not the rotation speed N of the engine 2 is 0 based on the vehicle information (rotation speed N of the engine 2).

When the ECU 3 determines that the rotation speed N is 0, the ECU 3 performs the process of step S70. When the ECU 3 determines that the rotation speed N is not 0, that is, the rotation speed N is larger than 0, the ECU 3 performs the process of step S80.

In step S60, similarly to step S50, the ECU 3 determines whether or not the rotation speed N of the engine 2 is 0.

When the ECU 3 determines that the rotation speed N is 0, the ECU 3 performs the process of step S80. When the ECU 3 determines that the rotation speed N is not 0, that is, the rotation speed N is larger than 0, the ECU 3 performs the process of step S90.

In step S70, the ECU 3 selects gaseous fuel. As a result, gaseous fuel is supplied to the intake manifold 6. After that, the engine 2 is started using the gaseous fuel.

In step S80, the ECU 3 selects the liquid fuel. As a result, liquid fuel is supplied to the intake manifold 6. After that, the engine 2 is started using the liquid fuel.

The ECU 3 operates the starter 7 in order to start the engine 2 in step S70 and step S80 (and step S100 described later).

In step S90, the ECU 3 starts a fuel cut in which fuel is not supplied to the engine 2 and determines whether or not a predetermined time has elapsed.

The predetermined time is, for example, a time in which fuel remains in the intake manifold 6 in a predetermined amount or more so that the engine 2 can be started. By executing the fuel cut, the fuel is not injected into the intake manifold 6, so that the fuel in the intake manifold 6 is gradually reduced. The predetermined time is a standard for determining the remaining amount of fuel in the intake manifold 6.

When the ECU 3 determines that the predetermined time has elapsed after starting the fuel cut, the fuel does not remain in the intake manifold 6, so the process of step S80 is performed. When the ECU 3 determines that the predetermined time has not elapsed after starting the fuel cut, the fuel remains in the intake manifold 6, so the process of step S100 is performed.

If the fuel cut is not executed, the ECU 3 determines that the predetermined time has not elapsed after starting the fuel cut, and performs the process of step S100.

In step S100, the ECU 3 selects the gaseous fuel as in step S70.

In step S110, the ECU 3 determines whether or not the accelerator pedal 112 has been depressed. Specifically, the ECU 3 determines whether or not the accelerator pedal 112 has been depressed based on the driver information (depressing and / or depressing the accelerator pedal 112).

When the ECU 3 determines that the accelerator pedal 112 has been depressed, the ECU 3 executes the process of step S80. Therefore, the ECU 3 switches from the gaseous fuel to the liquid fuel so that the liquid fuel is used as the fuel for the engine 2. On the other hand, when the ECU 3 determines that the accelerator pedal 112 is not depressed, the ECU 3 ends the process.

As described above, in the ECU 3 according to the embodiment, when the vehicle speed V is 0 and the engine 2 is restarted from the automatically stopped state in which the engine 2 is automatically stopped, the rotation speed N of the engine 2 is 0. A gaseous fuel is selected as the fuel of the engine 2 according to the determination that there is, and a liquid fuel is selected as the fuel of the engine 2 according to the determination that the rotation speed N of the engine 2 is larger than 0.

When restarting the engine 2 from the automatically stopped state in which the engine 2 is automatically stopped, gas fuel is selected as the fuel for the engine 2. The reason is that the rotation speed N of the engine 2 is 0, so that the piston, the intake valve, and the exhaust valve in the cylinder are stopped. As a result, the flow of gas to the exhaust side is suppressed, so that the gas fuel can be retained in the engine 2 (fuel chamber). Therefore, when the gas fuel is injected while the rotation speed N of the engine 2 is 0, the gas fuel can be efficiently burned and the startability of the engine 2 can be maintained. Therefore, since the opportunity to use the gaseous fuel increases, it is possible to improve the fuel efficiency while maintaining the startability of the engine 2.

On the other hand, the engine 2 is restarted from the automatic stop state before the engine 2 rotation speed N is larger than 0, that is, before the engine 2 rotation speed N becomes 0 (the brake pedal 114 is released or the clutch pedal 116 is released). In many cases, the driver wants to start the vehicle at an early stage. In such a case, the startability of the engine 2 can be maintained by selecting a liquid fuel having a better startability of the engine 2 in consideration of the intention of the driver.

As described above, by appropriately selecting the liquid fuel and the gaseous fuel according to the situation, it is possible to improve the fuel efficiency while maintaining the startability of the engine 2.

The ECU 3 according to the embodiment determines that the rotation speed N of the engine 2 is larger than 0 when the vehicle speed V is larger than 0 and the engine 2 is restarted from the automatically stopped state in which the engine 2 is automatically stopped. Gas fuel is selected as the fuel for the engine 2 according to the above. When the engine 2 is rotating, the engine 2 is easy to start. Therefore, by selecting a gaseous fuel as the fuel for the engine 2, it is possible to improve the fuel efficiency while maintaining the startability of the engine 2.

When the fuel cut is executed, the ECU 3 according to the embodiment selects a liquid fuel instead of a gaseous fuel according to the elapse of a predetermined time after starting the fuel cut. Thereby, when there is a high possibility that no fuel remains in the fuel chamber and / or the intake manifold 6 of the engine 2, the startability of the engine 2 can be maintained by selecting the liquid fuel.

When the gaseous fuel is selected, the ECU 3 according to the embodiment switches from the gaseous fuel to the liquid fuel so that the liquid fuel is used as the fuel for the engine 2 in response to the depression of the accelerator pedal 112 of the vehicle. .. When the accelerator pedal 112 is depressed, the driver often wants to start the vehicle at an early stage. Therefore, by considering the driver's intention and selecting a liquid fuel with better startability of the engine 2, the liquid fuel can be selected. The startability of the engine 2 can be maintained.

The ECU 3 according to the embodiment determines that the rotation speed N of the engine 2 is 0 when the vehicle speed V is larger than 0 and the engine 2 is restarted from the automatically stopped state in which the engine 2 is automatically stopped. Depending on the fuel, liquid fuel is selected. When the vehicle speed V is larger than 0, that is, when the engine 2 is restarted from the automatic stop state (the brake pedal 114 is released or the clutch pedal 116 is depressed) before the vehicle speed V becomes 0, the driver is early. There are many cases where you want to start the vehicle. In such a case, the startability of the engine 2 can be maintained by selecting a liquid fuel having a better startability of the engine 2 in consideration of the intention of the driver.

(3) Examples and Comparative Examples Next, Examples and Comparative Examples will be described with reference to FIG. FIG. 3 is an explanatory diagram for explaining Examples and Comparative Examples. In FIG. 3, the first and second embodiments are in a state in which the engine 2 is automatically stopped (so-called idling stop during deceleration) when the speed drops below a predetermined speed while the vehicle is decelerating. Reference numeral 3 is a state in which the engine 2 is automatically stopped after the vehicle is stopped (so-called idling stop when the vehicle is stopped).

In the first embodiment (see the dotted line in FIG. 3), the starting condition of the engine 2 is satisfied at t11. Since the vehicle speed V> 0 and the rotation speed N = 0 of the engine 2 at t11, the ECU 3 selects and uses the liquid fuel. Up to t11, the vehicle speed V and the rotation speed N of the first embodiment are the same as those of the second embodiment.

In the first embodiment, it can be seen that the rotation speed of the engine 2 is greatly increased at the timing of t12 after the starter 7 is operated, and the liquid fuel is efficiently burned.

In the second embodiment (see the solid line in FIG. 3), the starting condition of the engine 2 is satisfied at t21. Since the vehicle speed V = 0 and the rotation speed N> 0 of the engine 2 at t21, the ECU 3 selects and uses the liquid fuel.

In the second embodiment, it can be seen that the rotation speed of the engine 2 is greatly increased at the timing of t22 after the starter 7 is operated, and the liquid fuel is efficiently burned.

In the third embodiment (see the thin line in FIG. 3), the starting condition of the engine 2 is satisfied at t31. At t31, since the vehicle speed V = 0 and the rotation speed N = 0 of the engine 2, the ECU 3 selects and uses the gaseous fuel.

In the third embodiment, it can be seen that the rotation speed of the engine 2 is greatly increased at the timing of t32 after the starter 7 is operated, and the gaseous fuel is efficiently burned.

In Comparative Example 1 (see the two-dot chain line in FIG. 3), the starting condition of the engine 2 is satisfied at t21. Since the vehicle speed V = 0 and the rotation speed N> 0 of the engine 2 at t21, the ECU of the comparative example selects and uses the gaseous fuel. Up to t22, the vehicle speed V and the rotation speed N of Comparative Example 1 are the same as those of Example 2.

In Comparative Example 1, the rotation speed of the engine 2 slightly increased at the timing of t23 after the starter 7 was operated, and the rotation speed of the engine 2 thereafter did not increase either. This is due to the fact that the gaseous fuel is not burning efficiently.

(3) Other Embodiments Although the present invention has been described in detail using the above-described embodiments, it is clear to those skilled in the art that the present invention is not limited to the embodiments described in the present specification. Is. The present invention can be implemented as modifications and modifications without departing from the spirit and scope of the present invention as determined by the description of the scope of claims. Therefore, the description of the present specification is for the purpose of exemplary explanation and does not have any limiting meaning to the present invention.

For example, the engine 2 is in a state where the startability of the gaseous fuel is good (complete warm-up state), but the ECU 3 may determine (in advance) whether or not the engine 2 is in a completely warm-up state. .. The ECU 3 can make a determination based on the vehicle information. For example, when the water temperature (measured value) of the engine 2 is equal to or higher than a predetermined value, the ECU 3 can determine that the engine 2 is in a completely warmed state.

Since it is possible to improve fuel efficiency while maintaining the startability of the engine, it can be used for vehicles having an engine configured to be able to use liquid fuel and gaseous fuel.

1 Vehicle system 2 Engine 3 ECU
4 Fuel tank 5 Fuel switching device 6 Intake manifold 7 Starter 8 Drive wheel 9 Clutch 10 Transmission 11 Pedal 12 Water temperature sensor 13 Vehicle speed sensor 14 Fuel selection switch 15 Injector 16 Electromagnetic valve 41 1st fuel tank 42 2nd fuel tank 112 Accelerator pedal 114 Brake pedal 116 Clutch pedal

Claims (5)

A control device for controlling a vehicle having an engine configured to be able to use liquid fuel and gaseous fuel.
When the speed of the vehicle is 0 and the engine is restarted from the automatic stop state in which the engine is automatically stopped.
Depending on the determination that the engine speed is 0, the gas fuel is selected as the fuel for the engine.
A control device that selects the liquid fuel as the fuel in response to the determination that the engine speed is greater than zero. When the speed of the vehicle is higher than 0 and the engine is restarted from the automatic stop state, the gaseous fuel is selected as the fuel according to the determination that the rotation speed of the engine is larger than 0. The control device according to claim 1. When a fuel cut in which the fuel is not supplied is executed in the engine, a request to select the liquid fuel instead of the gaseous fuel according to the elapse of a predetermined time after starting the fuel cut. Item 2. The control device according to Item 2. 2. When the gaseous fuel is selected, the gas fuel is switched to the liquid fuel so that the liquid fuel is used as the fuel for the engine in response to the depression of the accelerator pedal of the vehicle. Or the control device according to 3. When the speed of the vehicle is higher than 0 and the engine is restarted from the automatic stop state, the liquid fuel is selected as the fuel according to the determination that the rotation speed of the engine is 0. The control device according to claim 1.

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