Brake pedal emulator

Abstract

A pedal emulator includes a housing having a first housing portion defining a first chamber and a second housing portion defining a second chamber, the second housing portion being movable relative to the first housing portion. The pedal emulator also includes a first spring that is compressed while the second housing portion moves a first distance relative to the first housing portion, a second spring that is compressed in parallel with the first spring while the second housing portion moves a second distance relative to the first housing portion after the second housing portion has moved the first distance, and a third spring that is compressed in parallel with the first and second springs while the second housing portion moves a third distance relative to the first housing portion after the second housing portion has moved the second distance.

Description

[Technical Field]

[0001] <Field> The present disclosure relates to a pedal emulator for a vehicle. [Background technology]

[0002] <Background> A brake-by-wire vehicle's brake pedal does not utilize a traditional connection to other components of the braking system, such as a mechanical connection to a vacuum or hydraulic brake system. In some brake-by-wire systems, a sensor monitors how far the driver presses the brake pedal. This distance is used to determine the amount of braking force required. A control unit or computer then determines how much hydraulic pressure is needed, and an electric pump is used to generate that pressure, for example, causing a caliper to press against the brake disc to stop the vehicle. DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0003] <Summary> Brake-by-wire systems have many advantages. However, they lack the "feel" of traditional braking systems that drivers are accustomed to. Therefore, there is a need for a pedal emulator that is reliable, compact, relatively inexpensive to manufacture, and can replicate the "feel" of a traditional brake pedal system.

[0004] Aspects of the present disclosure are directed, among other things, to systems and methods for emulating the feel of a traditional brake pedal. [Means for solving the problem]

[0005] One example provides a pedal emulator for a vehicle, the pedal emulator including a housing including a first housing portion defining a first chamber and a second housing portion defining a second chamber, the second housing portion being movable relative to the first housing portion, the pedal emulator further including: a first spring that is compressed while the second housing portion moves a first distance relative to the first housing portion; a second spring that is compressed in parallel with the first spring while the second housing portion moves a second distance relative to the first housing portion after the second housing portion moves the first distance; and a third spring that is compressed in parallel with the first and second springs while the second housing portion moves a third distance relative to the first housing portion after the second housing portion moves the second distance.

[0006] Another aspect provides a brake pedal assembly for a vehicle including a brake pedal, a bracket, a pedal arm rotatably connected between the brake pedal and the bracket, the pedal arm arranged to rotate in response to application of force to the brake pedal, and a pedal emulator compressed by the pedal arm as the pedal arm rotates. The pedal emulator includes a housing including a first housing portion and a second housing portion arranged to move relative to the first housing portion when the pedal arm rotates; a first spring that is compressed while the second housing portion moves a first distance relative to the first housing portion; a second spring that is compressed in parallel with the first spring while the second housing portion moves a second distance relative to the first housing portion after the second housing portion moves the first distance; and a third spring that is compressed in parallel with the first spring and the second spring while the second housing portion moves a third distance relative to the first housing portion after the second housing portion moves the second distance relative to the first housing portion. [Brief explanation of the drawings]

[0007] The accompanying drawings, in which like reference numerals indicate identical or functionally similar elements throughout the separate views, and together with the following detailed description, which are incorporated in and form a part of this specification, further illustrate examples, instances, and / or aspects of concepts that comprise the claimed subject matter and serve to explain various principles and advantages of the examples, instances, and / or aspects.

[0008] [Figure 1] FIG. 1 is a cross-sectional view of a brake pedal assembly in a relaxed state, according to some embodiments.

[0009] [Figure 2] FIG. 2 is a cross-sectional view of a brake pedal assembly in an operating state, according to some embodiments.

[0010] [Figure 3] FIG. 3 is a graph illustrating a force-displacement curve of a pedal emulator, according to some embodiments.

[0011] [Figure 4] FIG. 4 is a cross-sectional view of a pedal emulator in an uncompressed state, according to some embodiments.

[0012] [Figure 5] FIG. 5 is a cross-sectional view of a pedal emulator in a compressed state, according to some embodiments.

[0013] [Figure 6] FIG. 6 illustrates a spring diagram for a pedal emulator when no braking force is applied to the pedal emulator, according to some embodiments.

[0014] [Figure 7] FIG. 7 illustrates a spring diagram of a pedal emulator compressed by a first amount, according to some embodiments.

[0015] [Figure 8]FIG. 8 illustrates a spring diagram of a pedal emulator compressed by a second amount, according to some embodiments.

[0016] [Figure 9] FIG. 9 illustrates a spring diagram for a fully compressed pedal emulator, according to some embodiments.

[0017] Those skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of the embodiments.

[0018] Where appropriate, components of the apparatus and methods are represented by conventional symbols in the drawings, and only specific details relevant to understanding the illustrated examples, cases, and aspects are shown, so as not to obscure the present disclosure with details that will be readily apparent to those skilled in the art having the benefit of the description herein. DETAILED DESCRIPTION OF THE INVENTION

[0019] <Detailed explanation> 1 and 2 show cross-sectional views of a brake pedal assembly 100 according to some embodiments. The brake pedal assembly 100 includes, among other things, a brake pedal 105 coupled to the end of a pedal arm 110. The pedal arm 110 is rotatably coupled to a bracket 115 included in the brake pedal assembly 100, which applies a brake pedal force F to the brake pedal 105. p 1 shows the brake pedal 105 when a brake pedal force F is applied to the pedal arm 110. p 2 shows the brake pedal assembly 100 in a relaxed state with no brake pedal force F applied. p1 shows the brake pedal assembly 100 in an operated or braking state with a force being applied to the braked pedal 105, thereby causing rotation of the pedal arm 110 relative to the bracket 115.

[0020] 1 and 2, the brake pedal assembly 100 is operably coupled to a pedal emulator 120 designed to replicate the feel of a conventional braking system. As will be described in more detail below, the pedal emulator 120 applies a brake pedal force F to the brake pedal 105. p For example, the brake pedal force F p When a brake pedal force F is applied to the brake pedal 105, the pedal arm 110 rotates and engages the pedal emulator 120 by means of an actuating member 125. As the pedal arm 110 rotates, the actuating member 125 applies a brake pedal force F p Braking force F proportional to b to the pedal emulator 120, thereby compressing the pedal emulator 120. The pedal arm 110 rotates, applying a braking force F b When the pedal emulator 120 is applied, it compresses and generates a reaction force F that resists rotation of the pedal arm 110. c That is, the pedal emulator 120 generates the brake pedal force F p is applied to the brake pedal 105, a reaction force F that replicates the feel of a conventional braking system. c 3 shows an exemplary force curve 300 of the force output of the pedal emulator 120 versus linear compression of the pedal emulator 120.

[0021] 4 and 5 show cross-sectional views of a pedal emulator 120 according to some embodiments. FIG. 4 shows a cross-sectional view of the pedal emulator 120 in a fully relaxed or uncompressed state, and FIG. 5 shows a cross-sectional view of the pedal emulator 120 in a compressed state. The pedal emulator 120 includes, among other things, a cylindrical housing having a first, or outer, housing portion 405 and a second, or inner, housing portion 410 operable to move relative to the outer housing portion 405. The outer housing portion 405 defines a first cylindrical chamber 415, and the inner housing portion 410 defines a second cylindrical chamber 420. When the pedal emulator 120 is in the relaxed state (FIG. 4), the inner housing portion 410 extends almost completely outward from the first chamber 415 of the outer housing portion 405. 5, when the pedal emulator 120 is in a compressed state, the inner housing portion 410 slides into the first chamber 415. The diameter of the first chamber 415 is larger than the diameter of the inner housing portion 410 such that the inner housing portion 410 is received by the first chamber 415 during compression of the pedal emulator 120.

[0022] In operation, the outer housing portion 405 is secured to the bracket 115 such that the outer housing portion 405 is stationary relative to the brake pedal assembly 100. For example, the outer housing portion 405 may include a shroud 425 or similar structure that is used to attach the outer housing portion 405 to the bracket 115. In contrast, the inner housing portion 410 is coupled to the pedal arm 110 such that rotation of the pedal arm 110 causes movement of the inner housing portion 410 relative to the brake pedal assembly 100. In the illustrated example, the pedal arm actuating member 125 engages a notch 430 formed in the inner housing portion 410, thereby causing linear movement of the inner housing portion 410 as the pedal arm 110 rotates. Thus, a brake pedal force F is applied to the brake pedal 105. pWhen pressure is applied, rotation of the pedal arm 110 pushes or slides the inner housing portion 410 into the first chamber 415 of the outer housing portion 405 (FIG. 2).

[0023] As shown in FIGS. 4 and 5, the inner housing portion 410 is received by the open end 432 of the first housing portion 405. As further shown in FIGS. 4 and 5, the open end 435 of the second chamber 420 is sealed by a gland 440. A bushing 445 is mounted in a central opening of the gland 440 and is positioned to receive a piston shaft 450. A first end of the piston shaft 450 is coupled to a closed end 455 of the first chamber 415, and a second end of the piston shaft 450 extends through the bushing 445 and into the second chamber 420. That is, the piston shaft 450 extends longitudinally through the length of the first chamber 415 and through the bushing 445 and into the second chamber 420. A piston cap 460 is mounted on the second end of the piston shaft 450 that extends into the second chamber 420. When the pedal emulator 120 is in a relaxed or uncompressed state (FIG. 4), the piston cap 460 abuts the gland 440. However, when the pedal emulator 120 is compressed and the inner housing portion 410 slides into the first chamber 415, the gland 440 is linearly displaced from the piston cap 460 (FIG. 5). That is, the gland 440 is displaced linearly from the piston cap 460 (FIG. 5) by the braking force F. b When power is applied to the pedal emulator 120 , the piston slides along the piston shaft 450 , away from the piston cap 460 , and further into the first chamber 415 .

[0024] The pedal emulator 120 also includes a spring system housed within the first and second chambers 415, 420 of the cylindrical housing. In the illustrated example, the spring system includes two first stage springs 465A, 465B, a second stage spring 470, and a third stage spring 475. As described in more detail below, the springs 465A, 465B, 470, and 475 are connected in a quasi-parallel arrangement, meaning that when the pedal emulator 120 is compressed by the pedal arm 110, one or more springs are compressed in parallel at a given time. As the spring system is compressed during operation of the brake pedal assembly 100, the pedal emulator 120 generates a reaction force F that follows the force curve 300 shown in FIG. c Generate.

[0025] The first stage spring 465A and the second stage spring 470 are disposed within the first chamber 415 defined by the outer housing portion 405. In one aspect, the first stage spring 465A and the second stage spring 470 are disposed coaxially around the piston shaft 450 within the first chamber 415. In the illustrated example, the diameter of the second stage spring 470 is larger than the diameter of the first stage spring 465A such that the second stage spring 470 also coaxially surrounds the first stage spring 465A. The relaxed, or uncompressed, length of the first stage spring 465A is longer than the relaxed length of the second stage spring 470. As illustrated, when the pedal emulator 120 is in the relaxed, or uncompressed, state ( FIG. 4 ), the first stage spring 465A is held in place between the gland 440 and the closed end 455 of the first chamber 415. That is, while the pedal emulator 120 is in a relaxed state, a first end of the first stage spring 465A abuts the closed end 455 of the first chamber 415, and a second end of the first stage spring 465A abuts the gland 440. As a result, no mechanical fasteners or adhesives are required to hold the first stage spring 465A in place within the first chamber 415. Therefore, fewer components can be used to construct the pedal emulator 120, thereby reducing the cost and complexity of manufacturing the pedal emulator 120.

[0026] Unlike the first stage spring 465A, however, the second stage spring 470 is not long enough to contact both the closed end 455 of the first chamber 415 and the gland 440 while the pedal emulator 120 is in a relaxed state. Instead, as shown in FIG. 4 , a first end of the second stage spring 470 is held in place by a first retainer 480 at the closed end 455 of the first chamber 415, while a second end of the second stage spring 470 is spaced a first distance X1 from the gland 440. Thus, as described in more detail below, the gland 440 moves the first distance X1 during compression of the pedal emulator 120 before the second stage spring 470 is engaged by the gland 440. In some examples, the first retainer 480 is coupled to the closed end 455 of the first chamber 415 via a friction fit. For example, the first retainer 480 can be seated in a notch formed in the closed end 455 of the first chamber 415. In such a case, no adhesive or mechanical fasteners are required to hold the first retainer 480 in place while the pedal emulator 120 is in a relaxed state. In other examples, the first retainer 480 is coupled to the closed end 455 of the first chamber 415 using adhesive and / or mechanical fasteners.

[0027] 4 and 5, the first stage spring 465B and the third stage spring 475 are disposed within the second chamber 420 defined by the inner housing portion 410. The relaxed, or uncompressed, length of the first stage spring 465B is longer than the relaxed length of the third stage spring 475. Thus, as shown in FIG. 4, when the pedal emulator 120 is in a relaxed, or uncompressed state, the first stage spring 465B is held in place between the piston cap 460 and the closed end 485 of the first chamber 415. That is, while the pedal emulator 120 is in a relaxed state, a first end of the first stage spring 465B abuts the closed end 485 of the second chamber 420, and a second end of the first stage spring 465B abuts the piston cap 460. In this regard, no mechanical fasteners or adhesives are used to hold the first stage spring 465B in place within the first chamber 420. Rather, as shown, the first stage spring 465B is held in place solely by the tension force applied by the first stage spring 465B to the closed end 485 of the second chamber 420 and the piston cap 460. Thus, the pedal emulator 120 can be manufactured at reduced cost and complexity compared to pedal emulators that include various additional components.

[0028] Unlike the first stage spring 465B, the third stage spring 475 is not long enough to contact both the closed end 485 of the second chamber 420 and the piston cap 460 while the pedal emulator 120 is in a relaxed state. Rather, as shown in FIG. 4 , a first end of the third stage spring 475 is held in place by a second retainer 490 disposed at the closed end 485 of the second chamber 420, while a second end of the third stage spring 475 is spaced a second distance X2 from the piston cap 460. The second distance X2 is greater than the first distance X1, such that during compression of the pedal emulator 120, the inner housing portion 410 moves the second distance X2 into the first chamber 415 before the third stage spring 475 engages the piston cap 460. In some instances, the second retainer 490 is coupled to the closed end 485 of the second chamber 420 via a friction fit. For example, the second retainer 490 can be seated within a notch formed in the closed end 485 of the second chamber 420. In such a case, no adhesive or mechanical fasteners are required to hold the second retainer 490 in place while the pedal emulator 120 is in a relaxed state. In other examples, the second retainer 490 is coupled to the closed end 485 of the second chamber 420 using adhesive and / or mechanical fasteners.

[0029] In some examples, first stage springs 465A, 465B are implemented as springs having approximately the same spring constant. In other examples, first stage springs 465A, 465B have different spring constants. In some examples, second stage spring 470 has a spring constant greater than the respective spring constants of first stage springs 465A, 465B. In such cases, second stage spring 470 has stronger spring characteristics than first stage springs 465A, 465B. In some examples, third stage spring 475 has a spring constant greater than the respective spring constants of first stage springs 465A, 465B and second stage spring 470. Thus, in such examples, third stage spring 475 has the strongest spring characteristics when compared to first stage springs 465A, 465B and second stage spring 470.

[0030] As described above, the pedal emulator 120 generates a reaction force F that mimics the feel of a conventional brake pedal when actuated by the pedal arm 110 during braking. c The reaction force F is modeled by the force curve 300 shown in FIG. c changes with movement of inner housing portion 410 into first chamber 415. As shown in FIG. 3, force curve 300 exhibits two inflection points, resulting in a reaction force F c The rate of change of the reaction force F varies non-linearly through the full compression of the spring system contained in the pedal emulator 120. As further shown in FIG. c includes three stages: a first stage force response, a second stage force response, and a third stage force response. As used herein, the term "force response" refers to the cumulative reaction force F generated by the pedal emulator 120 through a given amount of travel of the inner housing portion 410. c The reaction force F generated by the pedal emulator 120 c is the braking force F applied to the pedal emulator 120 b It should be understood that the magnitude is approximately equal to, and in the opposite direction to,

[0031] The first stage force response of the pedal emulator 120 is provided by first stage springs 465A, 465B compressed in parallel. The second stage force response of the pedal emulator 120 is provided by first stage springs 465A, 465B compressed in parallel with second stage spring 470. The third stage force response of the pedal emulator 120 is provided by first stage springs 465A, 465B, second stage spring 470, and third stage spring 475 compressed in parallel with each other. Each force response stage corresponds to a braking force F applied to the pedal emulator 120. b This will be explained below in relation to FIGS. 3 and 6 to 9, in which FIG.

[0032] Figure 6 shows the braking force F b1 shows the spring system included in the pedal emulator 120 just before a braking force F is applied to the pedal emulator 120 by the pedal arm 110. b Before the reaction force F is applied, the pedal emulator 120 is in a relaxed or uncompressed state. As a result, the pedal emulator 120 applies little or no reaction force F while in the relaxed state. c No compression pedal emulator 120 to output braking force F b When the pedal emulator 120 receives a force curve 300, the pedal emulator 120 outputs a first stage force response. The first stage force response occurs when the first stage springs 465A, 465B are compressed in parallel over a first distance X1. That is, the first stage springs 465A, 465B act in parallel to generate a reaction force F corresponding to the first stage of the force curve 300. c while inner housing portion 410 moves a first distance X1 into first chamber 415.

[0033] For example, during the first stage force response of the pedal emulator 120, the first stage spring 465A is compressed between the closed end 455 of the first chamber 415 and the gland 440, and the first stage spring 465B is compressed between the closed end 485 of the second chamber 420 and the piston cap 460. However, neither the second stage spring 470 nor the third stage spring 475 are engaged and / or compressed during the first stage force response of the pedal emulator 120. As further shown in FIG. 3 , the first stage reaction force F c increases as the inner housing portion 410 moves linearly into the first chamber 415. Thus, the first stage force response of the pedal emulator 120 depends on the position of the inner housing portion 410 and the spring constants of each of the parallel-connected first stage springs 465A, 465B.

[0034] When the inner housing portion 410 moves a first distance X1 into the first chamber 415, a reaction force F is output by the pedal emulator 120. c reaches a first inflection point where the gland 440 engages with the second stage spring 470. Referring now to FIGS. 3 and 7, the braking force Fb Continued application of the force F results in a second stage force response of the pedal emulator 120. The second stage force response is generated by the first stage springs 465A, 465B and the second stage spring 470 compressing in parallel over a third distance X3, where X3 is the difference between the first and second distances X1 and X2. That is, the first stage springs 465A, 465B and the second stage spring 470 act in parallel to generate a reaction force F in response to the second stage of the force curve 300 as the inner housing portion 410 moves the third distance X3 beyond the first distance X1 into the first chamber 415. c Output.

[0035] For example, during the second stage force response of the pedal emulator 120, the first stage spring 465A and the second stage spring 470 are compressed between the closed end 455 of the first chamber 415 and the gland 440, and the first stage spring 465B is compressed between the closed end 485 of the second chamber 420 and the piston cap 460. However, the third stage spring 475 is not engaged and / or compressed during the second stage force response of the pedal emulator 120. Also, as shown in FIG. 3, the second stage reaction force F c is a first stage reaction force F as the inner housing portion 410 moves linearly into the first chamber 415. c The second stage force response of the pedal emulator 120 therefore depends on the position of the inner housing portion 410 and the spring constants of each of the parallel-connected first stage springs 465A, 465B and second stage spring 470.

[0036] When the inner housing portion 410 moves a second distance X2 into the first chamber 415, a reaction force F is output by the pedal emulator 120. c reaches a second inflection point where the third stage spring 475 engages the piston cap 460. Referring now to FIGS. 3 and 8, the braking force F bContinued application of the force F results in a third stage force response of the pedal emulator 120. The third stage force response is generated by the first stage springs 465A, 465B, the second stage spring 470, and the third stage spring 475 being compressed in parallel over a fourth distance X4. That is, the first stage springs 465A, 465B, the second stage spring 470, and the third stage spring 475 act in parallel to generate a reaction force F corresponding to the third stage of the force curve 300 as the inner housing portion 410 moves the fourth distance X4 beyond the second distance X2 into the first chamber 415. c Output.

[0037] For example, during a third stage force response of the pedal emulator 120, the first stage spring 465A and the second stage spring 470 are compressed between the closed end 455 of the first chamber 415 and the gland 440, and the first stage spring 465B and the third stage spring 475 are compressed between the closed end 485 of the second chamber 420 and the piston cap 460. As shown in FIG. 3, the third stage reaction force F c is a first and second stage reaction force F as the inner housing portion 410 moves linearly into the first chamber 415. c The third stage force response of the pedal emulator 120 therefore depends on the position of the inner housing portion 410 and the spring constants of the parallel-connected first stage springs 465A, 465B, second stage spring 470, and third stage spring. After the inner housing portion 410 moves a fourth distance X4 into the first chamber 415 during the third stage force response, the pedal emulator 120 is fully compressed at which point the inner housing portion 410 has moved a total distance of X5 (FIG. 9).

[0038] As described above, the pedal emulator 120 includes two first stage springs 465A, 465B connected in parallel. The two first stage springs 465A, 465B provide redundancy so that failure of one of the first stage springs 465A, 465B does not significantly adversely affect the performance of the pedal emulator 120. However, in some examples, the pedal emulator 120 includes only a single first stage spring 465. In some examples, the pedal emulator 120 also includes redundant second and / or third stage springs 470, 475 similar to the redundant first stage springs 465A, 465B described herein. In some examples, the pedal emulator 120 includes additional stages of springs, such as fourth, fifth, and / or sixth stage springs. In such examples, the pedal emulator 120 experiences additional stages of force response during operation of the brake pedal assembly 100.

[0039] Specific examples have been described above. However, those skilled in the art will recognize that various modifications and changes can be made without departing from the scope of the invention as set forth in the following claims. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present teachings.

[0040] Benefits, advantages, solutions to problems, and any elements that may cause or make more noticeable any benefit, advantage, or solution should not be construed as critical, necessary, or essential features or elements of any or all of the claims. The present invention is defined solely by the appended claims, including any amendments made during the pendency of this application, and all equivalents of those claims as issued.

[0041] The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is understood that the Abstract will not be used to interpret or limit the scope of the claims. Moreover, it will be understood that in the foregoing Detailed Description, various features are grouped together in various examples for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed examples require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed example. Accordingly, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as separately claimed subject matter.

Claims

1. a first housing portion defining a first chamber; a housing including a second housing portion defining a second chamber, the second housing portion being movable relative to the first housing portion; a first spring that is compressed while the second housing portion moves a first distance relative to the first housing portion; a second spring that is compressed in parallel with the first spring while the second housing portion moves a second distance relative to the first housing portion after the second housing portion moves the first distance; a third spring that is compressed in parallel with the first spring and the second spring while the second housing portion moves a third distance relative to the first housing portion after the second housing portion moves the second distance.

2. the first spring and the second spring are housed within the first chamber; 2. The pedal emulator of claim 1, wherein the second spring is engaged by the second housing portion after the second housing portion moves the first distance relative to the first housing portion.

3. an open end of the second housing portion received by the open end of the first housing portion; 3. The pedal emulator of claim 2, wherein the open end of the second housing portion is sealed by a gland.

4. the first spring is compressed between the gland and the closed end of the first housing portion when the second housing portion moves the first distance; 4. The pedal emulator of claim 3, wherein the second spring is compressed parallel to the first spring between the gland and the closed end of the first housing portion after the second housing portion has moved the first distance.

5. a shaft extending from the first chamber through an opening formed in the gland and into the second chamber; 4. The pedal emulator of claim 3, further comprising a piston including: a cap attached to an end of the shaft disposed in the second chamber, the cap abutting the gland before the second housing portion moves relative to the first housing portion.

6. 6. The pedal emulator of claim 5, wherein the first and second springs are coaxially disposed along the shaft.

7. the third spring is housed within the second chamber; 6. The pedal emulator of claim 5, wherein the third spring is compressed between the cap and the closed end of the second housing portion after the second housing portion moves the second distance relative to the first housing portion.

8. a fourth spring contained within the second chamber; 6. The pedal emulator of claim 5, wherein the fourth spring is compressed in parallel with the first spring when the second housing portion moves the first distance relative to the first housing portion.

9. a first end of the second spring coupled to a first retainer disposed at a closed end of the first chamber; 2. The pedal emulator of claim 1, wherein a first end of the third spring is coupled to a second retainer disposed at a closed end of the second chamber.

10. 2. The pedal emulator of claim 1, wherein the spring constant of the third spring is greater than the spring constant of the first spring and the spring constant of the second spring.

11. Brake pedal and A bracket and a pedal arm rotatably coupled between the brake pedal and the bracket, the pedal arm being arranged to rotate in response to application of force to the brake pedal; a pedal emulator that is compressed by the pedal arm as the pedal arm rotates, a housing including a first housing portion and a second housing portion arranged to move relative to the first housing portion when the pedal arm rotates; a first spring that is compressed while the second housing portion moves a first distance relative to the first housing portion; a second spring that is compressed in parallel with the first spring while the second housing portion moves a second distance relative to the first housing portion after the second housing portion moves the first distance; and a third spring compressed in parallel with the first spring and the second spring while the second housing portion moves a third distance relative to the first housing portion after the second housing portion moves the second distance.

12. the first spring and the second spring are contained within a first chamber defined by the first housing portion; 12. The brake pedal assembly of claim 11, wherein the second spring is engaged by the second housing portion after the second housing portion moves the first distance relative to the first housing portion.

13. an open end of the second housing portion received by the open end of the first housing portion; The brake pedal assembly of claim 12 , wherein the open end of the second housing portion is sealed by a gland.

14. the first spring is compressed between the gland and the closed end of the first housing portion when the second housing portion moves the first distance; 14. The brake pedal assembly of claim 13, wherein the second spring is compressed parallel to the first spring between the gland and the closed end of the first housing portion after the second housing portion moves the first distance.

15. The brake pedal assembly of claim 13, wherein the second housing portion defines a second chamber.

16. a shaft extending from the first chamber through an opening formed in the gland and into the second chamber; 16. The brake pedal assembly of claim 15, further comprising a piston including a cap attached to an end of the shaft disposed within the second chamber, the cap abutting the gland before the second housing portion moves relative to the first housing portion.

17. the third spring is housed within the second chamber; 17. The brake pedal assembly of claim 16, wherein the third spring is compressed between the cap and the closed end of the second housing portion after the second housing portion moves the second distance relative to the first housing portion.

18. a fourth spring contained within the second chamber; 17. The brake pedal assembly of claim 16, wherein the fourth spring is compressed in parallel with the first spring when the second housing portion moves the first distance relative to the first housing portion.

19. a first end of the second spring coupled to a first retainer disposed at a closed end of the first chamber; 12. The brake pedal assembly of claim 11, wherein a first end of the third spring is coupled to a second retainer disposed in the closed end of the second chamber.

20. The brake pedal assembly of claim 11 , wherein the spring rate of the third spring is greater than the spring rate of the first spring and the spring rate of the second spring.

Images