A method for activating engine braking and vehicle hydraulic retarder in association

Abstract

The application discloses an activation method of associating engine braking and a whole vehicle hydraulic retarder, and comprises the following steps: S1, calibrating an overspeed calibration value of an engine rotating speed; S2, acquiring an engine operating state by using a controller, comparing the engine rotating speed with the overspeed calibration value, and determining that the engine rotating speed is greater than the overspeed calibration value; and S3, executing strategy I and / or strategy II according to the engine rotating speed. The application has the advantages of simple control and improved driving safety.

Description

Technical Field

[0001] This invention relates to the field of automotive braking methods, and in particular to a method for activating engine braking and a vehicle hydraulic retarder. Background Technology

[0002] Mining trucks and heavy-duty trucks have large tonnage, and relying solely on the braking system for heavy-load downhill driving suffers from problems such as severe brake pad wear, insufficient braking force, and high braking risks. Therefore, these vehicles now incorporate auxiliary braking systems—engine braking (exhaust braking, cylinder braking) and a vehicle-wide hydraulic retarder. When going downhill, the user activates the hydraulic retarder to reduce the transmission speed, thereby reducing the engine speed, and simultaneously triggers the engine braking switch. The cylinder braking acts on the engine valves, increasing the piston's resistance, while the exhaust braking acts on the exhaust pipe, increasing exhaust resistance and further reducing engine speed. Currently, mining trucks are widely equipped with hydraulic retarders and engine braking devices. However, activation of the hydraulic retarder and engine braking also requires manual activation by pressing a request switch. In actual use, drivers often find it difficult to activate the hydraulic retarder or engine braking in a timely manner as needed. Improper operation can lead to engine overspeed when the vehicle is heavily loaded downhill, causing bearing wear and even connecting rod breakage, resulting in serious engine damage.

[0003] The braking operation of current mining trucks is inconvenient, requiring the driver to manually press the hydraulic retarder switch and the engine cylinder brake activation switch. In actual use, the operation is cumbersome and frequent, and the driver may forget to press the brake switch, resulting in engine overspeed.

[0004] Chinese patent document CN101837738A discloses a hydraulic retarder drive controller and its control method. The control method includes the following steps: a signal processing module receives and processes temperature sensing signals from an oil temperature sensor and a water temperature sensor in the hydraulic retarder; a control unit receives or reads a user-input gear position, and, based on whether the oil temperature or water temperature corresponding to the temperature sensing signal exceeds its respective temperature threshold, the output control unit controls the hydraulic retarder's electromagnetic control valve to downshift and adjust the output pressure at the corresponding gear. This method fills a gap in hydraulic retarder drive controllers.

[0005] Chinese patent document CN112503117B discloses a method for realizing the immediate application of 100% braking torque by a hydraulic retarder in emergency or special circumstances.

[0006] The above background information is provided only to aid in understanding the concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0007] The purpose of this invention is to propose an activation method for the hydraulic retarder, in-cylinder brake, and exhaust brake without manually pressing the hydraulic retarder switch or the engine cylinder brake activation switch.

[0008] Therefore, this invention proposes a method for activating the associated engine braking and vehicle hydraulic retarder.

[0009] Preferably, the present invention may also have the following technical features:

[0010] A method for activating a vehicle hydraulic retarder that is associated with engine braking includes the following steps:

[0011] S1: Calibrate engine speed overspeed calibration value;

[0012] S2: Use the controller to obtain the engine operating status, compare the engine speed with the overspeed calibration value, and determine that the engine speed is greater than the overspeed calibration value;

[0013] S3: Execute Strategy I and / or Strategy II based on engine speed:

[0014] Strategy I: When the engine speed is greater than the overspeed calibration value A, determine whether to activate the in-cylinder braking and / or exhaust braking based on the throttle opening; when the speed is greater than the overspeed calibration value B, activate both exhaust braking and in-cylinder braking simultaneously.

[0015] Strategy II: Based on the number of gears n of the hydraulic retarder, calibrate the overspeed calibration values ​​P1, P2, ..., P1 corresponding to each gear from low to high. n-1 P n ;

[0016] When the engine speed is greater than the overspeed calibration value P1 and less than the overspeed calibration value P n At that time, the throttle opening value is obtained, and the auxiliary braking system is activated based on whether the throttle opening exceeds the calibrated value X.

[0017] When the engine speed is greater than the overspeed calibration value P n At this time, the retarder is activated in the N position (maximum gear), which simultaneously activates the in-cylinder braking and exhaust braking.

[0018] Furthermore, the controller is an ECU.

[0019] Furthermore, in Strategy I, the speed of the overspeed calibration value A is greater than or equal to the minimum speed of engine overspeed, and less than the speed of the overspeed calibration value B; at the speed of the overspeed calibration value A, if the throttle opening is greater than 0, the engine continues to operate normally; if the throttle opening is 0, the in-cylinder braking or exhaust braking is activated.

[0020] Furthermore, in Strategy II,

[0021] If the throttle opening does not exceed the calibrated value X, the engine continues to operate normally;

[0022] If the throttle opening exceeds the calibrated value X, the auxiliary braking system is activated, and the corresponding gear of the hydraulic retarder is activated according to the current speed.

[0023] Furthermore, when the rotational speed reaches the overspeed calibration value P n Initiate in-cylinder braking or exhaust braking.

[0024] Furthermore, when activating the second-to-last gear of the hydraulic retarder, in-cylinder braking or exhaust braking can be applied.

[0025] The beneficial effects of this invention compared to existing technologies include: This invention eliminates the need for manually pressing the hydraulic retarder switch and the engine cylinder brake activation switch; it automatically activates the hydraulic retarder, cylinder brake, and exhaust brake based on changes in engine speed. This is particularly effective in handling continuous uphill and downhill road conditions. Employing two strategies to control engine speed and braking allows for setting overspeed calibration values ​​according to different needs, demonstrating strong adaptability. In this invention, the automatic triggering of cylinder brake and hydraulic retarder is achieved through J1939 communication messages. The required commands are transmitted via the CAN bus, thereby triggering cylinder brake and hydraulic retarder. The J1939 communication message is a universal message, compatible with various vehicle manufacturers, improving compatibility. Strategy I of this invention automatically triggers the engine cylinder brake function for auxiliary braking based on engine speed. Strategy II of this invention automatically triggers the vehicle's hydraulic retarder based on engine speed; and can trigger multi-level hydraulic retarder settings according to different overspeed conditions. Attached Figure Description

[0026] Figure 1 This is the control flowchart of the present invention. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to specific embodiments and the accompanying drawings. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope or application of the present invention.

[0028] Non-limiting and non-exclusive embodiments will be described with reference to the following figures, wherein the same reference numerals denote the same parts unless otherwise specifically stated.

[0029] A method for activating a vehicle hydraulic retarder that is associated with engine braking includes the following steps:

[0030] S1: Calibrate engine speed overspeed calibration value;

[0031] S2: The engine operating status is obtained using a controller, and the engine speed is compared with the overspeed calibration value to determine that the engine speed is greater than the overspeed calibration value; the controller is an ECU;

[0032] S3: Execute Strategy I and / or Strategy II based on engine speed:

[0033] Strategy I: When the engine speed is greater than the overspeed calibration value A, determine whether to activate the in-cylinder braking and / or exhaust braking based on the throttle opening; when the speed is greater than the overspeed calibration value B, activate both exhaust braking and in-cylinder braking simultaneously.

[0034] Wherein, the speed of overspeed calibration value A is greater than or equal to the minimum speed of engine overspeed, and less than the speed of overspeed calibration value B. At the speed of overspeed calibration value A, if the throttle opening is greater than 0, the engine continues to operate normally; if the throttle opening is 0, the auxiliary braking system is activated, preferably the in-cylinder braking or exhaust braking, to reduce the engine speed.

[0035] If the aforementioned auxiliary braking system is activated, the engine speed continues to rise. When the engine speed exceeds the overspeed calibration value B, both exhaust braking and cylinder braking are activated simultaneously. Although the speed at the overspeed calibration value B is lower than the engine runaway speed, when the engine speed exceeds B, the speed is already very high and quite dangerous. Therefore, at the speed at the overspeed calibration value B, even if the driver presses the accelerator pedal, the auxiliary braking system will not disengage. However, when the engine speed drops below the overspeed calibration value B, pressing the accelerator pedal disengages the auxiliary braking system, and the car gains power. This strategy has good braking and power output effects on roads with continuous uphill and downhill sections. If the car's speed exceeds the overspeed calibration value B when it reaches the bottom of the slope, and it needs to go uphill again before the speed drops below the overspeed calibration value B, pressing the accelerator pedal at this time will not provide power. After the car has gone uphill for a certain distance, the engine speed drops below the overspeed calibration value B, at which point pressing the accelerator pedal will disengage the auxiliary braking system, regain power, and allow the car to smoothly complete the uphill climb.

[0036] Strategy II: Based on the number of gears n of the hydraulic retarder, calibrate the overspeed calibration values ​​P1, P2, ..., P1 corresponding to each gear from low to high. n-1 P nThis embodiment takes a five-speed hydraulic retarder as an example, where the overspeed calibration value P1 corresponds to the first speed of the hydraulic retarder; the overspeed calibration value P2 corresponds to the second speed of the hydraulic retarder; the overspeed calibration value P3 corresponds to the third speed of the hydraulic retarder; the overspeed calibration value P4 corresponds to the fourth speed of the hydraulic retarder; and the overspeed calibration value P5 corresponds to the fifth speed of the hydraulic retarder.

[0037] When the engine speed is greater than the overspeed calibration value P1 and less than the overspeed calibration value P n At that time, the throttle opening value is obtained, and the auxiliary braking system is activated based on whether the throttle opening exceeds the calibrated value X.

[0038] If the throttle opening does not exceed the calibrated value X, the engine continues to operate normally;

[0039] If the throttle opening exceeds the calibrated value X, the auxiliary braking system is activated, and the corresponding gear of the hydraulic retarder is activated according to the current speed; preferably, when the speed is greater than the overspeed calibration value P n-1 At this time, the second-to-last gear of the hydraulic retarder is activated, and the in-cylinder braking or exhaust braking is activated simultaneously.

[0040] When the engine speed is greater than the overspeed calibration value P n At this time, the retarder is activated in neutral (maximum setting), simultaneously activating both cylinder braking and exhaust braking. The engine speed exceeds the overspeed calibration value P. n The engine speed is already very high, which greatly affects driving safety. In order to protect the driver's life and health, the auxiliary braking system is fully activated to quickly reduce the engine speed.

[0041] In step S3, Strategy I and Strategy II are two different control paths. Both strategies can be triggered simultaneously, or one of them can be triggered individually. This approach has a wide range of applications and ensures high vehicle safety.

[0042] In Strategy II, when the engine speed is below the overspeed calibration value, the throttle opening is used as the key condition for activating the auxiliary braking system. When the throttle opening meets the activation criteria for the auxiliary braking system, the hydraulic retarder is activated in stages according to the engine speed to obtain a greater braking effect. Furthermore, to achieve an even more significant braking effect, the overspeed calibration value P can be reached at higher engine speeds. n Before applying cylinder braking or exhaust braking, it is preferable to apply cylinder braking or exhaust braking when activating the second-to-last gear of the hydraulic retarder.

[0043] In Strategy II, set the throttle opening calibration value X, which is greater than 0.

[0044] Strategy II's control method also provides good braking and power output on roads with continuous uphill and downhill sections. For example, if the car's speed is greater than the overspeed calibration value P1 after it reaches the bottom of the slope and before it continues uphill, the driver can lightly press the accelerator pedal (throttle opening less than the calibration value X) to obtain power in order to quickly and stably reach the top of the slope.

[0045] In Strategy II, set the throttle opening calibration value X, and the calibration value X equals 0.

[0046] Those skilled in the art will recognize that numerous variations are possible with respect to the above description, and the embodiments and figures are merely for describing one or more specific implementations.

[0047] Although exemplary embodiments of the invention have been described and illustrated, those skilled in the art will understand that various changes and substitutions can be made thereto without departing from the spirit of the invention. Furthermore, many modifications can be made to adapt specific situations to the doctrine of the invention without departing from the central concepts of the invention described herein. Therefore, the invention is not limited to the specific embodiments disclosed herein, but may include all embodiments and equivalents that fall within the scope of the invention.

Claims

1. A method for activating a vehicle hydraulic retarder that is associated with engine braking and the vehicle's overall hydraulic retarder, characterized in that: Includes the following steps: S1: Calibrate engine speed overspeed calibration value; S2: Use the controller to obtain the engine operating status, compare the engine speed with the overspeed calibration value, and determine that the engine speed is greater than the overspeed calibration value; S3: Execute Strategy II based on engine speed: Strategy II: Based on the number of gears n of the hydraulic retarder, calibrate the overspeed calibration values ​​P1, P2 ... Pn-1, Pn sequentially from low to high; When the engine speed is greater than the overspeed calibration value P1 and less than the overspeed calibration value Pn, the throttle opening value is obtained, and the auxiliary braking system is activated based on whether the throttle opening exceeds the calibration value X. When the engine speed is greater than the overspeed calibration value Pn, the retarder is activated in the n position, and the cylinder braking and exhaust braking are activated at the same time. In Strategy II, If the throttle opening does not exceed the calibrated value X, the engine continues to operate normally; If the throttle opening exceeds the calibrated value X, the auxiliary braking system is activated, and the corresponding gear of the hydraulic retarder is activated according to the current speed.

2. The activation method for the associated engine braking and vehicle hydraulic retarder as described in claim 1, characterized in that: The controller is an ECU.

3. The activation method for the associated engine braking and vehicle hydraulic retarder as described in claim 1, characterized in that: Apply in-cylinder braking or exhaust braking before the engine speed reaches the overspeed calibration value Pn.

4. The activation method for the associated engine braking and vehicle hydraulic retarder as described in claim 3, characterized in that: When activating the second-to-last gear of the hydraulic retarder, apply in-cylinder braking or exhaust braking.

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