DE102008026531B4 - Method for regulating the brake pressure in an electronically controlled braking system of a motorcycle and electronic braking system for a motorcycle - Google Patents

Abstract

Method for regulating the brake pressure in an electronically controlled brake system of a motorcycle (30), wherein a holding brake pressure (PMHG) is built up (42) and then maintained (43) in at least one wheel brake circuit after the motorcycle has been stopped or almost stopped by a driver, which is a The motorcycle (30) is prevented from rolling away, the holding brake pressure (PMHG) being determined from a brake actuation pressure (PVR) of the front wheel (VR) and a brake actuation pressure (PHR) of the rear wheel (HR), which were necessary to stop the motorcycle (30), characterized in that the holding brake pressure (PMHG) is additionally determined as a function of a vehicle deceleration (a) achieved during stopping.

Description

The invention relates to a method according to the preamble of claim 1 and an electronic braking system according to the preamble of claim 9.

Over the last few decades, the motorcycle has developed from a cost-effective means of transport to a leisure vehicle in which both the safety and comfort of the driver are increasingly placed in the foreground.

Similar to automobiles a few years ago, motorcycles are increasingly being equipped with anti-lock braking systems (ABS). From the EP 0 548 985 B1 For example, an anti-lock device for motorcycles is known. From the DE 102005021492 A1 a method for counteracting the rolling away of a motor vehicle is also known.

Due to increased safety and/or increased comfort, integral brake systems are increasingly being used on motorcycles, which support the driver during the braking process and thus ensure an optimized braking distance. An “integral brake system” is a brake system in which a brake from the other brake circuit is additionally braked when the hand brake lever or foot brake lever is actuated, for example by actively building up pressure. Both brakes can be controlled by operating a single actuating element. Integral brake systems for motorcycles are, for example, from the DE 38 03 563 A1 and DE 103 16 351 A1 known.

In addition, driver assistance systems are becoming increasingly important in the motorcycle sector. In particular, the demand for cost-effective driver assistance systems that utilize existing hardware to implement additional comfort and/or safety functions is increasing.

The motorcycle driver assistance systems mentioned above also include systems with a stop and start function, which hold the motorcycle at a standstill, for example on a slope, and enable it to start moving if the driver wishes. An electronically controlled braking system with stopping and starting functions for a motorcycle is being developed in the DE 10 2007 025 273 A1 described. The size of the holding brake pressure is selected as a predetermined, constant value or depending on the load status of the motorcycle, the type of motorcycle and / or the slope measured by a longitudinal acceleration sensor.

The invention is based on the object of providing a method for keeping a motorcycle at a standstill and an electronic braking system for a motorcycle, which ensures that the motorcycle is held safely, even on a slope.

This object is achieved according to the invention by the method according to claim 1 and the electronic brake system according to claim 9.

A method for regulating the brake pressure in an electronically controlled brake system of a motorcycle is presented, with a holding brake pressure being built up and then maintained in at least one wheel brake circuit, in particular in the rear wheel brake circuit, after the motorcycle has stopped or almost stopped by a driver, which prevents it from rolling away of the motorcycle, in particular without further actuation of a brake actuation element by the driver, the holding brake pressure being determined from a brake actuation pressure of the front wheel and a brake actuation pressure of the rear wheel, which were necessary to stop the motorcycle.

The invention is based on the idea that the size/strength of the holding brake pressure, which is built up and maintained in a wheel brake circuit after the motorcycle has been stopped by a driver to prevent a motorcycle from rolling away when at a standstill or near a standstill, depending on a brake actuation pressure of the front wheel and a to determine the brake actuation pressure of the rear wheel that was needed to stop the motorcycle. As a result, the motorcycle is held securely by the driver even without further actuation of a brake actuation element. In addition, the actuation and the strength of the actuation of the individual brake actuation elements for the front and rear wheels of a motorcycle are taken into account.

In order to achieve greater stabilization of the motorcycle, the holding brake pressure is preferably built up in the rear wheel brake circuit.

The brake actuation pressure present at the time of stopping is preferably selected as the brake actuation pressure of the front wheel and/or the rear wheel necessary for stopping. Alternatively, in order to achieve a more reliable determination of a brake operating pressure, it is preferred to determine the brake operating pressure as an average of brake operating pressures of the corresponding wheel over a predetermined period of time during stopping.

The brake actuation pressure of a wheel is preferably determined by a pressure sensor, which determines a master brake cylinder pressure. This ensures an accurate determination of the brake actuation pressure. In order to determine the brake actuation pressures of both wheels with sufficient precision, both the brake actuation pressure of the front wheel and the brake actuation pressure of the rear wheel are particularly preferably determined by a pressure sensor, which determines the master brake cylinder pressure of the respective wheel brake circuit.

According to the invention, the holding brake pressure is additionally determined as a function of a vehicle deceleration achieved during stopping. By taking into account the vehicle deceleration achieved with known brake actuation pressures of the wheels, the road inclination is taken into account, whereby a situation-adapted dimensioning of the holding pressure is achieved. This also offers the advantage that the road inclination is taken into account without the need for an additional sensor to be attached to the motorcycle to measure the inclination of the road.

Preferably, the road inclination is determined based on at least one brake actuation pressure and the vehicle deceleration achieved during stopping, and the holding brake pressure is then selected depending on the road incline. The specific road inclination can then also be taken into account by other vehicle control systems, e.g. when dimensioning the brake pressure reduction during a starting function. This saves an additional sensor for measuring the road inclination.

According to an advantageous development of the invention, the road inclination is determined based on predetermined characteristics or a predetermined map or based on a predetermined functional relationship between the brake actuation pressure(s) and the vehicle deceleration (a). The characteristic curves or the characteristic map or the functional relationship are/are predetermined vehicle-specifically. Corresponding specifications are particularly preferably stored in a control unit of the motorcycle, most preferably in the brake control unit of the motorcycle. By purely evaluating the road inclination angle from variables already present in the vehicle or from variables that are easy to determine (brake actuation pressure and deceleration), costs, e.g. for an inclination sensor, are saved.

The holding brake pressure is preferably formed as a sum of a base value and a pressure value that is dependent on the road inclination. The basic value is determined from the brake actuation pressure of the front wheel and the brake actuation pressure of the rear wheel, which were necessary to stop the motorcycle. This results in separate consideration of the actuation-dependent holding pressure component and the road inclination-dependent holding pressure component, whereby an at least partially situation-adapted holding brake pressure is determined even in the event of an incorrectly determined road inclination angle. The pressure value, which depends on the road inclination, is particularly preferably determined based on at least one brake actuation pressure and the vehicle deceleration achieved during stopping. As already explained above, this has the advantage of cost-effective evaluation of variables that are already present in the vehicle or can be easily determined.

The brake actuation pressure of the front wheel and the brake actuation pressure of the rear wheel are preferably added up or weighted in order to determine the holding brake pressure or the basic value of the holding brake pressure from the summed brake actuation pressure. The different braking effects on the front and rear wheels are taken into account by a weighted sum of the brake actuation pressure of the front and rear wheels with different weighting coefficients.

The holding brake pressure is preferably selected as the sum or weighted sum of the actuation brake pressures on the front and rear wheels increased by a predetermined value. Adding a given value reduces the risk of rolling away. An actuation brake pressure is the brake pressure applied at the moment the motorcycle is stopped or a brake pressure averaged over a predetermined period of time during the stop.

According to a preferred embodiment of the method according to the invention, the holding brake pressure is only determined from the brake actuation pressures of the front and rear wheels, which were necessary to stop the motorcycle, and / or a road inclination is determined based on at least one brake actuation pressure and the vehicle deceleration achieved during stopping if No braking control, such as anti-lock braking control, was carried out when the motorcycle was stopped. Only with uncontrolled braking is the deceleration achieved approximately proportional to the brake pressure applied and the gradient/incline of the road.

The strength of the holding brake pressure, which is built up and maintained as part of the holding function, is preferably dependent on the Road inclination determined. This allows the strength of the holding brake pressure to be chosen appropriately for the situation, which ensures that the motorcycle is held safely, but also does not result in unnecessary oversizing of the brake pressure. This ensures safe holding even on very steep slopes.

The invention also relates to an electronic braking system for a motorcycle, in which a method according to at least one of claims 1 to 8 is carried out.

The method according to the invention is preferably carried out in an integral brake system of a motorcycle, in which when a brake actuation element, for example the hand brake lever or the foot brake lever, is actuated, an active brake pressure build-up is additionally carried out on a wheel brake of the other brake circuit, which is not hydraulically connected to the actuated brake actuation element .

An advantage of the invention lies in the improved safety when stopping on a slope. The invention relieves the burden on the driver and allows him to concentrate better on the traffic. Another advantage of the invention lies in the situation-adapted determination of the holding brake pressure. Regardless of whether the rider operates one brake lever or both brake levers, or whether stopping is carried out on the flat or on a slope/incline, the holding brake pressure is dimensioned in such a way that the motorcycle is secured against rolling away.

Further preferred embodiments of the invention emerge from the subclaims and the following description based on figures.

Show it schematically

• 1 a representation of a motorcycle on a slope,
• 2 a flowchart of a motorcycle driver assistance system with a hold function, and
• 3 an exemplary relationship between vehicle deceleration and brake pressure for different road inclinations.

1 shows a schematic representation of an exemplary motorcycle on a slope. Motorcycle 30 with control unit 31 and a wheel speed sensor 32 on the front wheel VR and rear wheel HR is located on slope 33. Control unit 31 is designed to control the brake system and to control the implementation of a holding function or holding and starting function.

In 2 An example of a method for preventing a vehicle from rolling away (stop function) is shown in the form of a schematic flow diagram. In block 40 it is checked whether motorcycle 30 is stationary or almost stationary. In block 41 it is checked whether an activation condition is met. If both conditions are met simultaneously or in close succession, a holding brake pressure P _MHG is first built up in a wheel brake circuit, for example in the rear wheel brake circuit (block 42) and then this holding brake pressure P _MHG is (approximately) maintained (block 43).

It is therefore possible to hold vehicle 30 safely on hill 33 by actively building up pressure, for example in the rear wheel brake circuit, without the driver having to actuate the brakes further on a brake actuation element.

A standstill or almost standstill of the motorcycle 30 (block 40) is detected, for example, based on the signals from the wheel speed sensors 32. If the wheel speed, for example of the rear wheel HR, is less than a predetermined threshold value, an (approximate) standstill of the motorcycle 30 is detected. Instead of the wheel speed, another wheel rotation speed variable, which corresponds to the wheel speed, can also be used to detect standstill.

According to one example, the activation condition (block 41) is an actuation of a brake actuation element, for example the handbrake lever. The activation of the active brake pressure build-up (holding brake pressure P _MHG ) takes place on the driver side via actuation of a brake lever when or after the motorcycle 30 is detected (approximately) at a standstill (block 40).

To activate the hold function, the driver, for example, applies the front wheel brake (handbrake lever) with a higher pressure than the pressure required to bring the vehicle to a standstill. The system then builds up sufficient pressure P _MHG in the rear wheel brake circuit (block 42) and then maintains it (block 43) to keep the motorcycle on the slope 33. The pressure P _MHG remains (almost) constant even if the driver releases the handbrake lever again or partially releases it.

In order to determine the necessary holding pressure P _MHG according to an exemplary embodiment of the method according to the invention, the brake pressure applied by the driver to stop the vehicle on the front wheel P _VR and rear wheel P _HR is recorded over a certain, predetermined period of time ΔT and the required holding pressure P _MHG is calculated therefrom. The period ΔT is specified for each vehicle.

According to the example, the brake pressures P _VR and P _HR are determined via a master cylinder pressure sensor in the brake circuit of the front wheel and in the brake circuit of the rear wheel.

wobei:

• P_MHG: Haltebremsdruck,
• P_VR, P_HR: Bremsdrücke bzw. Hauptzylinder-Drücke an Vorderrad VR und Hinterrad HR während des Anhaltens (getrennt ermittelt), z.B. über einen vorgegebenen Zeitraum ΔT ermittelt, z.B. zeitlich gemittelt,
• C1, C2: Gewichtungsfaktoren bei der Berücksichtigung von Vorderrad- und Hinterradbremsdruck, und
• A1: additiver Druckwert.

For example, the holding pressure P _MHG is calculated using the following formula: $${\text{P}}_{\text{MHG}}\left[\text{bar}\right]=\text{<figure-callout id="1" label="C" filenames="DE102008026531B4\_0005.png" state="{{state}}">C</figure-callout>}1*{\text{P}}_{\text{VR}}+\text{<figure-callout id="2" label="C" filenames="DE102008026531B4\_0005.png" state="{{state}}">C</figure-callout>}2*{\text{P}}_{\text{MR}}+\text{<figure-callout id="1" label="A" filenames="DE102008026531B4\_0005.png" state="{{state}}">A</figure-callout>}1$$

where:

• P _MHG : holding brake pressure,
• P _VR , P _HR : Brake pressures or master cylinder pressures on the front wheel VR and rear wheel HR during stopping (determined separately), e.g. determined over a predetermined period ΔT, e.g. averaged over time,
• C1, C2: Weighting factors when taking into account front and rear wheel brake pressure, and
• A1: additive pressure value.

According to the example, the weighting factors are C1 = 1.5 and C2 = 1.0 and the additive value A1 = 2.

Another functional relationship and/or other values of the parameters (in the case of the relationship according to equation (1): weighting factors C1, C2 and additive pressure value A1) are also possible, based on which the holding brake pressure P _MHG is derived from the brake pressures P _VR and P _HR is determined. A corresponding connection with parameter values is specified for a specific motorcycle 30, for example in control unit 31.

A holding pressure P _MHG determined according to equation (1) may not be sufficient for stopping on a mountain 33 with a larger gradient β. Either a re-sizing (increase) of the holding pressure P _MHG can then be carried out after a vehicle movement (rolling away of the motorcycle 30) has been detected, or in order to safely avoid rolling away, a larger offset value A1 can be applied to the determined stopping pressure, for example according to equation (1). C1 * P _VR + C2 * P _HR , are added. However, the latter generally leads to an uncomfortable “sticking” of the motorcycle 30 when starting off.

For more precise dimensioning of the holding pressure P _MHG, which is dependent on the slope β of the mountain 33, the necessary holding pressure P _MHG is determined as follows according to another exemplary embodiment of the method according to the invention. The ratio (the relationship) between a brake pressure P controlled for stopping and the deceleration a achieved is used. The greater the slope β of the hill 33 on which the driver stops, the greater the deceleration a, which is achieved with the same applied brake pressure P (compared to the level).

The brake pressure P used to take into account the road inclination β can be the front wheel brake pressure P _VR already explained above or the rear wheel brake pressure P _HR or a weighted average between the two (P=d1*P _VR +d2*P _HR , with d1, d2: weight factors).

The delay a is, for example, determined (outside of controlled braking) from the wheel speeds (e.g. by numerical time derivation), which are measured, for example, with the wheel speed sensors 32. For example, the vehicle reference speed determined in an anti-lock braking system can be used. Alternatively, the delay a can be obtained from a wheel deceleration by suitable filtering.

In 3 an exemplary relationship between a brake pressure P controlled for stopping, the deceleration a achieved and the road gradient β is shown schematically. For this purpose, the vehicle deceleration a is plotted as a function of the brake pressure P for different road inclinations β, characteristic curve 1 describes the relationship for the level (β=0°), characteristic curve 2 for a gradient of 10%, characteristic curve 3 for a gradient of 20%, characteristic curve 4 for a gradient of 30%.

As long as it is not a controlled braking (e.g. braking with anti-lock control), the deceleration a achieved is approximately proportional to the controlled pressure P and the incline/descent β of the road.

The relationship between the brake pressure P applied to stop, the deceleration a achieved and the road inclination β is vehicle-dependent. It is measured at the factory and then stored in a control unit 31 in the form of a map or characteristic curves or a functional relationship. Based on the map or the characteristic curves or the functional relationship, the road inclination β is determined from a certain deceleration a and a certain brake pressure P.

To take into account the inclination β of the road, a specific holding pressure base value is used, which is derived from the stopping pressure. Brake pressure P _VR and P _HR is determined, a slope-dependent value (offset) A(β) is added.

For example, a slope-dependent value (offset) A(β) is added to the holding pressure (base value) determined according to equation (1) in addition or alternatively to the additive pressure value A1 in order to obtain the holding brake pressure P _MHG .

For example, the base value is determined according to equation (1) with the parameters C1=1, C2=1 and A1=0. The holding brake pressure P _MHG is then calculated from equation (2): $${\text{P}}_{\text{MHG}}\left[\text{bar}\right]={\text{P}}_{\text{VR}}+{\text{P}}_{\text{MR}}+\text{A}\left(\mathrm{\beta }\right)$$

If a stopping pressure of 10 bar is determined when vehicle 30 stops on the plane (β=0°), this is sufficient on the plane to prevent vehicle 30 from rolling away. If a stopping pressure of 10 bar is also determined when stopping on a hill with a 20% gradient, a holding pressure P _MHG of 10 bar is not sufficient to prevent vehicle 30 from rolling away due to the downhill force. However, if a pressure offset A(β) dependent on the slope β is added to the determined stopping pressure, the vehicle can also be prevented from rolling away on the slope with the same brake pressure (initially) controlled by the driver.

An advantage of the method according to the invention is that the holding pressure P _MHG can be dimensioned depending on the gradient β, ie it does not have to be oversized in the plane. This leads to improvements in comfort, as there is no need to re-size the vehicle if it rolls away and “sticking” on the plane can still be prevented when starting off.

Claims (9)

Method for regulating the brake pressure in an electronically controlled brake system of a motorcycle (30), wherein a holding brake pressure (P _MHG ) is built up (42) and then maintained (43) in at least one wheel brake circuit after the motorcycle has been stopped or almost stopped by a driver, which prevents the motorcycle (30) from rolling away, the holding brake pressure (P _MHG ) being determined from a brake actuation pressure (P _VR ) of the front wheel (VR) and a brake actuation pressure (P _HR ) of the rear wheel (HR), which is used to stop the motorcycle (30 ) were necessary, characterized in that the holding brake pressure (P _MHG ) is additionally determined as a function of a vehicle deceleration (a) achieved during stopping. Procedure according to Claim 1 , characterized in that the holding brake pressure (P _MHG ) is determined depending on the road inclination (β), which is determined based on at least one brake actuation pressure (P _VR , P _HR ) and a vehicle deceleration (a) achieved during stopping. Procedure according to Claim 2 , characterized in that the road inclination (β) is based on predetermined characteristics or a predetermined map or based on a predetermined relationship, which is/are stored in particular in a control unit, from the brake actuation pressure (P _VR , P _HR ) and the vehicle deceleration (a) is determined. Method according to at least one of the Claims 1 until 3 , characterized in that at least one brake actuation pressure (P _VR , P _HR ) is determined by a pressure sensor which determines a master brake cylinder pressure, in particular that the brake actuation pressure (P _VR ) of the front wheel (VR) and the brake actuation pressure (P _HR ) of the rear wheel (HR ) is determined in each case by a pressure sensor, which determines the master brake cylinder pressure of the respective wheel brake circuit. Method according to at least one of the Claims 1 until 4 , characterized in that the brake actuation pressure (P _VR ) of the front wheel (VR) and / or the brake actuation pressure (P _HR ) of the rear wheel (HR) as the brake actuation pressure present at the time of stopping or as an average of brake actuation pressures of the wheel over a predetermined Period (ΔT) is/are determined during stopping. Method according to at least one of the Claims 1 until 5 , characterized in that a base value of the holding brake pressure (P _MHG ) is determined from the brake actuation pressure (P _VR ) of the front wheel (VR) and the brake actuation pressure (P _HR ) of the rear wheel (HR), which were necessary to stop the motorcycle, and that a pressure value (A(ß)) dependent on the road inclination (β) is added to this base value, which is determined in particular on the basis of at least one brake actuation pressure (P _VR , P _HR ) and a vehicle deceleration (a) achieved during stopping. Method according to at least one of the Claims 1 until 6 , characterized in that the holding brake pressure (P _MHG ) or the base value of the holding brake pressure as a, in particular weighted (C1, C2), sum of the brake actuation pressure (P _VR ) of the front wheel (VR) and the brake actuation pressure (P _HR ) of the rear wheel ( HR) is determined. Method according to at least one of the Claims 1 until 7 , characterized in that the holding brake pressure (P _MHG ) is only determined from the brake actuation pressure (P _VR ) of the front wheel (VR) and the brake actuation pressure (P _HR ) of the rear wheel (HR), which were necessary to stop the motorcycle (30). , and in particular depending on the vehicle deceleration (a) achieved during the stop, if no brake control, in particular anti-lock control, was carried out when the motorcycle (30) was stopped. Electronic braking system for a motorcycle (30), characterized in that it includes a method according to at least one of Claims 1 until 8th is carried out.

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